New waves in Physical Land Resources

New waves in Physical Land Resources 

Proceedings of the Workshop for Alumni of the 

M.Sc. programmes in Soil Science, Eremology and 

Physical Land Resources 

Refresher Course supported by the Flemish Interuniversity Council 

(VLIR-UOS) 

Edited by 

Dominique Langouche & Eric Van Ranst 

GHENT UNIVERSITY 

3-9 SEPTEMBER 2006

New waves in 

Physical Land Resources 

Proceedings of the Workshop for 

Alumni of the M.Sc. programmes in 

Soil Science, Eremology and Physical 

Land Resources 

ISBN 9789076769950 

Edited by 

Eric Van Ranst & Dominique Langouche 

GHENT UNIVERSITY 

3-9 SEPTEMBER 2006

TABLE OF CONTENTS 

PREFACE 

OPENING ADDRESS BY PROF. E. VAN RANST, CHAIRMAN STEERING COMMITTEE 

PHYSICAL LAND RESOURCES AND PROMOTOR OF THE MASTER PROGRAMME (UGENT) 

OPENING ADDRESS BY RECTOR P. VAN CAUWENBERGHE (UGENT) 

OPENING ADDRESS BY MS. K. VERBRUGGHEN, DIRECTOR OF VLIR-UNIVERSITY 

DEVELOPMENT CO-OPERATION SECTION 

OPENING LECTURES ....................................................................................................................................... 1 

SUSTAINABLE LAND MANAGEMENT IN THE ETHIOPIAN HIGHLANDS............................................ 2 

MITIKU HAILE..................................................................................................................................................... 2 

NEW CHALLENGES OF SOIL SCIENCE TO FOOD SECURITY WITH SPECIAL REFERENCE TO 

CHINA ............................................................................................................................................................. 14 

TANG HUAJUN & ZHOU WEI............................................................................................................................. 14 

WORKS ON EROSION PROCESSES UNDER WIND-DRIVEN RAIN CONDITIONS IN I.C.E ................ 24 

GUNAY ERPUL 1 & DONALD GABRIELS 2 ............................................................................................................ 24 

WORKSHOP THEME A – SOIL AND GROUNDWATER POLLUTION AND REMEDIATION.......... 36 

SUB-THEME : MANAGING CONTAMINATED SOILS USING PHYTOREMEDIATION................... 37 

ERIK MEERS, FILIP M. G. TACK, MARC G. VERLOO ......................................................................................... 37 

COMPARISON OF AMENDMENTS USED TO REMEDIATE ACID MINE TAILINGS: 

ENVIRONMENTAL AND AGRICULTURAL APPLICATIONS .................................................................. 39 

Kelly A. Senkiw and Tee Boon Goh * ............................................................................................................ 39 

STUDY ON THE EFFECTS OF TRADE VILLAGE WASTE ON ACCUMULATION OF Cu, Pb, Zn AND 

Cd IN AGRICULTURAL SOILS OF PHUNG XA VILLAGE, THACH THANH DISTRICT, HA TAY 

PROVINCE.................................................................................................................................................. 49 

Nguyen Huu Thanh 1 , Tran Thi Le Ha 1 * , Nguyen Duc Hung 1 , Tran Duc Hai 2 ............................................ 49 

METAL CONTAMINATION IN IRRIGATED AGRICULTURAL LAND: CASE STUDY OF NAIROBI 

RIVER BASIN, KENYA................................................................................................................................ 60 

P.N. Kamande 1* , F.M.G. Tack 2 ................................................................................................................... 60 

SUB-THEME : MANAGING GROUNDWATER POLLUTION FROM WASTE DISPOSAL SITES .... 63 

KRISTINE WALRAEVENS, MARLEEN COETSIERS, KRISTINE MARTENS, MARC VAN CAMP ............................... 63 

CONTAMINATION OF THE MARIMBA RIVER TRIBUTARY, ZIMBABWE, WITH Cu, Pb, Zn AND P BY 

INDUSTRIAL EFFLUENT AND SEWER LINE DISCHARGE................................................................... 66 

Bangira, C * .Wuta, M., Dube, H.M and Chipatiso, L................................................................................... 66 

CONTROLLING PHOSPHORUS (P) MOBILITY IN POORLY P SORBING SOILS: DRINKING-WATER 

TREATMENT RESIDUALS (WTR) TO THE RESCUE ............................................................................... 75 

S. Agyin-Birikorang 1* , G.A. O’Connor 1 and L.W. Jacobs 2 .......................................................................... 75 

Effects of WTR on P losses .......................................................................................................................... 84 

HEAVY METAL CONTAMINATION OF SOIL AND SURFACE WATER BY LEACHATES OF AN OPEN 

DUMP OF MUNICIPAL SOLID WASTE: A CASE STUDY OF OBLOGO LANDFILL IN THE GA WEST 

DISTRICT OF ACCRA, GHANA................................................................................................................. 87 

Abuaku Ebenezer*....................................................................................................................................... 87 

CONCLUSIONS.............................................................................................................................................. 89 

WORKSHOP THEME B – INTEGRATED SOIL FERTILITY MANAGEMENT .................................... 92 

SUB-THEME : USE OF ISOTOPE TECHNIQUES FOR ................................................................................... 93 

NUTRIENT MANAGEMENT ........................................................................................................................ 93 

P. BOECKX, K. DENEF, AND O. VAN CLEEMPUT ............................................................................................... 93 

ENHANCING THE AGRONOMIC EFFECTIVENESS OF NATURAL PHOSPHATE ROCK WITH 

POULTRY MANURE: A WAY FORWARD TO SUSTAINABLE CROP PRODUCTION .................... 95 

S. Agyin-Birikorang 1 *, M.K. Abekoe 2 , O.O. Oladeji 1 , S.K.A. Danso 2 ......................................................... 95 

THE EFFECT OF LIMING AN ACID NITISOL WITH EITHER CALCITE OR DOLOMITE ON 

TWO COMMON BEAN (Phaseolus vulgaris L.) VARIETIES DIFFERING IN ALUMINIUM 

TOLERANCE........................................................................................................................................... 108

E .N Mugai 1* , S.G Agong 1 and H. Matsumoto 2 ......................................................................................... 108 

EFFECT OF P FERTILISERS AND WEED CONTROL..................................................................... 117 

ON THE FATE OF P FERTILISERS APPLIED TO SOILS................................................................ 117 

UNDER SECOND-ROTATION PINUS RADIATA............................................................................... 117 

A. A. Rivaie 1 , P. Loganathan 2 , and R. W. Tillman 2 ................................................................................... 117 

SUB-THEME : ORGANIC FARMING IN THE TROPICS PRESENT SITUATION, POSSIBILITIES 

AND CHALLENGES................................................................................................................................... 120 

STEFAAN DE NEVE.......................................................................................................................................... 120 

LOW INPUT APPROACHES FOR SOIL FERTILITY MANAGEMENT VERIFIED FOR SEMI- 

ARID AREAS OF EASTERN UGANDA................................................................................................ 123 

Kayuki C.Kaizzi 1 , Byalebeka John 1 , Charles S. Wortmann 2 and Martha Mamo 2 ..................................... 123 

AMELIORATION OF ACID SULFATE SOIL INFERTILITY IN MALAYSIA FOR RICE CULTIVATION 

................................................................................................................................................................... 133 

J. Shamshuddin.......................................................................................................................................... 133 

WORKSHOP THEME C – LAND EVALUATION AND LAND DEGRADATION................................. 144 

SUB-THEME : LAND EVALUATION FOR SUSTAINABLE LAND MANAGEMENT & POLICY MAKING ................... 145 

A. VERDOODT & E. VAN RANST..................................................................................................................... 145 

OIL PALM AND RUBBER PRODUCTION MODEL FOR SUBSTITUING RUBBER WITH OIL 

PALM AND EVALUATING TO ESTABLISH OIL PALM INTO NORTHEAST THAILAND.......... 149 

S. Pratummintra 1 , E.Van Ranst 2 , H.Verplancke 2 , A. Verdoodt 2 ................................................................ 149 

SOIL PROPERTIES AND BIOLOGICAL DIVERSITY OF UNDISTURBED AND DISTURBED 

FORESTS IN MT. MALINDANG, PHILIPPINES ............................................................................... 162 

Renato D. Boniao 1* , Rosa Villa B. Estoista 2 , Carmelita G. Hansel 2 , Ron de Goede 4 , .............................. 162 

Olga M. Nuneza 3 , Brigida A. Roscom 3 , Sam James 5 , Rhea Amor C. Lumactud 1 , ..................................... 162 

Mae Yen O. Poblete 1 and Nonillon Aspe 3 .................................................................................................. 162 

SUB-THEME : LAND DEGRADATION : PRESSURES, INDICATORS AND RESPONSES ............... 173 

VARIOUS APPROACHES FOR SOIL EROSION RISK ASSESSMENT .................................................................... 173 

W. CORNELIS, D. GABRIELS, H. VERPLANCKE................................................................................................ 173 

INDICATORS AND PARTICIPATORY METHODS FOR MONITORING LAND DEGRADATION. A 

CASE STUDY IN THE MIGORI DISTRICT OF KENYA. ................................................................... 175 

Vincent de Paul Obade 1* , Eva De Clercq 2 ................................................................................................ 175 

PROPOSED PLAN OF ACTION FOR RESEARCH ON DESERTIFICATION IN THE SUDAN:... 181 

GEZIRA AND SENNAR STATES .......................................................................................................... 181 

Kamal Elfadil Fadul and Fawzi Mohamed Salih ...................................................................................... 181 

DIAGNOSTIC OF DEGRADATION PROCESSES OF SOILS FROM NORTHERN TOGO (WEST 

AFRICA) AS A TOOL FOR SOIL AND WATER MANAGEMENT..................................................... 187 

Rosa M Poch*, Josep M Ubalde ............................................................................................................... 187 

CONCLUSIONS............................................................................................................................................ 195 

WORKSHOP THEME D – SOIL SURVEY AND INVENTORY TECHNIQUES.................................... 196 

SUB-THEME : DEVELOPMENTS IN SOIL (ATTRIBUTE) MAPPING WITH AN APPLICATION IN 

MAPING GROUNDWATER DEPTH....................................................................................................... 197 

P.A. FINKE ...................................................................................................................................................... 197 

USING GEOGRAPHIC INFORMATION SYSTEMS AND GLOBAL POSITIONING SYSTEM TO MAP 

SOIL CHARACTERISTICS FOR LAND EVALUATION........................................................................... 199 

P. Wandahwa 1* J. A. Rota 1 , and D. O. Sigunga 2 ....................................................................................... 199 

SUB-THEME : DEVELOPMENTS IN GIS AND REMOTE SENSING WITH EMPHASIS ON HIGH 

RESOLUTION IMAGERY AND 3-D PRESENTATION TECHNIQUES ............................................ 208 

R. GOOSSENS .................................................................................................................................................. 208 

GEOMORPHOLOGY AND CLASSIFICATION OF SOME PLAINES AND WADIES ADJACENT TO 

GABEL ELBA, SOUTH EAST OF EGYPT................................................................................................ 210 

El-Badawi, M. and Abdel-Fattah, A. ......................................................................................................... 210 

HIGH RESOLUTION TERRAIN MAPPING AND VISUALIZATION OF CHANNEL MORPHOLOGY 

USING LiDAR AND IFSAR DATA............................................................................................................ 225 

Sudhir Raj Shrestha 1* , Dr. Scott N. Miller 2 ............................................................................................... 225 

SUB-THEME : DEVELOPMENTS IN SOIL SAMPLING AND PROXIMAL SENSING WITH 

APPLICATIONS IN PRECISION AGRICULTURE .............................................................................. 226 

M. VAN MEIRVENNE, U.W.A. VITHARANA L. COCKX ................................................................................... 226

ESTIMATING SPATIAL VARIABILITY OF SOIL SALINITY USING COKRIGING IN BAHARIYA OASIS, 

EGYPT....................................................................................................................................................... 228 

Kh. M. Darwish*, M.M. Kotb and R. Ali................................................................................................... 228 

SPATIAL VARIABILITY OF DRAINAGE AND PHOSPHATE RETENTION AND THEIR INTER 

RELATIONSHIP IN SOILS OF THE SOUTH-WESTERN REGION OF THE NORTH ISLAND, NEW 

ZEALAND.................................................................................................................................................. 242 

A.Senarath*, A.S.Palmer and R.W.Tillman............................................................................................... 242 

CONCLUSIONS........................................................................................................................................... 252 

WORKSHOP THEME E – SOIL PROCESSES AND ANALYTICAL TECHNIQUES........................... 254 

SUB-THEME : DEVELOPMENTS IN SOIL GENESIS AND MINERALOGY.............................................. 255 

VAN RANST E. & MEES F. ..............................................................................................................................255 

IMPACT OF ACID DEPOSITION ON CATION LEACHING FROM...................................................... 258 

Mt. TALANG AIRFALL ASH..................................................................................................................... 258 

Fiantis, D., Nelson 1 , E. Van Ranst 2 and J. Shamshuddin 3 ......................................................................... 258 

STONE LINES AND WEATHERING PROFILES OF FERRALLITIC SOILS IN NORTHEASTERN 

ARGENTINA ............................................................................................................................................. 269 

Morrás, H. 1* , Moretti, L. 1 , Píccolo, G. 2 , Zech,W. 3 ..................................................................................... 269 

PEDOGENESIS ALONG A HILLSLOPE TRAVERSE IN THE UPPER AFRAM BASIN, GHANA.......... 281 

T. Adjei-Gyapong, 1 E. Boateng, 1 * C. Dela Dedzoe, 1 W.R. Effland, 2 M.D. Mays 2 and J.K. Seneya 1 ......... 281 

INFLUENCE OF TITANOMAGNETITE ON DITHIONITE-CITRATE-BICARBONATE (DCB) AND 

OXALATE EXTRACTIONS IN WEATHERED DOLERITE ...................................................................... 283 

C. G. Algoe 1* , E. Van Ranst 2 , G. Stoops 3 ................................................................................................ 283 

SUB-THEME : DEVELOPMENTS IN SOIL MICROMORPHOLOGY .......................................................... 291 

STOOPS, G., MARCELINO, V., MEES, F............................................................................................................ 291 

SPHEROIDAL WEATHERING OF DOLERITE IN SURINAME: EVIDENCE FROM PHYSICAL, 

CHEMICAL AND MINERALOGICAL DATA ........................................................................................... 295 

C. G. Algoe 1* , E. Van Ranst 2 , G. Stoops 3 ................................................................................................ 295 

MICROMORPHOLOGICAL CHARACTERISTICS OF ANDISOLS IN WEST JAVA, INDONESIA ........ 296 

Mahfud Arifin * , Rina Devnita.................................................................................................................... 296 

MICROMORPHOLOGICAL FEATURES OF SOME SOILS IN THE AFRAM PLAINS (GHANA, WEST 

AFRICA).................................................................................................................................................... 307 

M.D. Mays 1 , W.R. Effland 2 , T. Adjei-Gyapong 3 , C.D. Dedzoe 3 and E. Boateng 4 *................................... 307 

CONCLUSIONS........................................................................................................................................... 308 

CLOSING ADDRESS BY PROF. E. VAN RANST, CHAIRMAN STEERING COMMITTEE 

PHYSICAL LAND RESOURCES AND PROMOTOR OF THE MASTER PROGRAMME (UGENT) 311 

AGENDA ........................................................................................................................................................... 314 

LIST OF PARTICIPANTS .............................................................................................................................. 318

PREFACE 

The 5th Refresher Course for alumni of our Master programmes is organised with the aim to 

point out needs for feedback, co-operation and support for alumni, and present information 

and means to fill gaps and remediate shortcomings. In addition, the objective is to brief the 

alumni on the latest developments in the field of Soil Science and Engineering Geology, 

within the expertise available at the International Centre for Physical Land Resources. 

While in the former editions of the Refresher Course, which took place in South-East 

Asia, Africa and Latin America, there was a strong accent on transfer of knowledge from the 

International Training Centre for Pos-Graduate Soil Scientists (ITC-Ghent), towards alumni, 

now an overall exchange of knowledge and information from alumni to staff and vice versa, 

as well as amongst alumni is envisaged. It is the intention to create or improve channels of 

communication as an indispensable vehicle for co-operation. 

This publication collects all contributions from alumni that were submitted for the 

different workshops organised in the frame of this Refresher Course. The contributions are 

arranged per workshop theme, and introduced by each scientific committee appointed for each 

workshop. Care is taken to add a selection of valuable references pertaining to each workshop 

theme.

Welcome 

WELCOME 

Opening Address by Prof. E. Van Ranst, Chairman Steering Committee Physical Land 

Resources and Promotor of the Master Programme (UGent) 

Opening Address by Rector P. Van Cauwenberghe (UGent) 

Opening Address by Ms. K. Verbrugghen, Director of VLIR-University Development 

Co-operation Section

Welcome 

Opening Address by Prof. E. Van Ranst, Chairman Steering 

Committee Physical Land Resources and Promotor of the Master 

Programme (UGent) 

Given at the occasion of the fifth refresher course for alumni of the Master of Science Programmes in 

Soil Science (UGent), Eremology (UGent) and Physical Land Resources (UGent-VUB) 

4 September 2006 

The Rector of Ghent University, 

The Director of the Secretariat for University Development Co-operation of the Flemish 

Interuniversity Council, 

Esteemed Guests, 

Dear Alumni, 

Dear Colleagues, 

Welcome at our 5 th refresher course for alumni. We are happy to be able to welcome today 

about 40 alumni. When we take into account all alumni who reacted to our call for 

participation, this number would have been around one hundred (100). However, financial 

constraints proved to be a stumbling stone for many. 

The 5 th Refresher Course for Alumni of our Master programmes is organised with the aim to 

point out needs for feedback, co-operation and support for alumni, and to present information 

and means to fill gaps and remediate shortcomings. In addition, it is the objective to brief the 

alumni on the latest developments in the field of Soil Science and Engineering Geology, 

within the expertise available at the International Centre for Physical Land Resources. 

While in the former editions of the Refresher Course, which took place in South-East Asia, 

Africa and Latin America, there was a strong accent on transfer of knowledge from the 

International Training Centre for Post-Graduate Soil Scientists towards the alumni, now an 

overall exchange of knowledge and information from alumni to staff and vice versa, as well 

as amongst alumni is aimed at. It is the intention to create or improve channels of 

communication as an indispensable vehicle for co-operation. 

We, the programme organisers, are proud and honoured that Prof. Van Cauwenberge, the 

Rector of Ghent University, which is hosting this workshop, has committed himself to address 

this meeting at the occasion of the opening. We know that he has a full agenda. In fact, his 

secretariat informed us that he has to be in Brussels today at eleven (11) ‘o clock, and he will 

have to leave us shortly after his opening address. 

We are also pleased with the presence of Ms. Verbrugghen, Director of VLIR-University 

Development Co-operation Section, and sponsor of this workshop, who kindly accepted to 

welcome you here today.

Welcome 

Since 1997, the financing and scholarships that "the International Course Programme's, 

including ours, receive from the Belgian Administration for Development Co-operation are 

being administered through the Flemish Interuniversity Council – or VLIR , and more in 

particular the department University Development Co-operation. VLIR is a familiar name for 

all our graduates since. 

Both distinguished speakers are invited to welcome the audience 

Prof. E. Van Ranst

Welcome 

Opening Address by Rector P. Van Cauwenberghe (UGent) 



Dear Alumni, 




It is my great pleasure and honour to welcome you at Ghent University. Ghent University has 

a long standing tradition of internationally oriented education and research. In fact, the 

international course programme in Physical Land Resources, which has roots back to 1963, is 

the very proof of this. And you – its alumni – are the living testimony. 

Up to this day, Ghent University is involved in many international projects and maintains 

intensive contacts with research institutes and laboratories all over the world. This 

university’s concern for the world beyond the national borders manifests itself foremost in the 

education and training of foreign students. 

Since 1963, up to this day, about 1000 alumni from over 90 countries worldwide graduated 

from the Master programmes in Soil Science, Eremology and Physical Land Resources at 

Ghent University and, since 1997, also at the Free University of Brussels. In the present day 

meeting, I see faces from more than 20 different nations, a number that without any doubt 

would have been much higher were it not for budgetary constraints. 

While the international course programme would not be successful without the day-to-day 

dedication of its promoters and staff, the programme is also highly indebted to you, the 

alumni. You act as scientific ambassadors by disseminating your knowledge into your home 

institution and country and as key persons in forming a bridge between your institution and 

Ghent University. Indeed, many of the research projects that have been and are being carried 

out, were set up through co-operation with graduates from this university. All initiatives that 

foster communication and networking and which reinforce ties between the university and its 

former students deserve our highest consideration and support. 

Yet, when exchanging knowledge care has to be taken to consider the local cultural, social 

and material reality. While for a soil scientist, it is as clear as mud that it is important to find a 

common ground, collaboration should consist of support, encouragement, catalysation and 

help from the North to find that little bit extra, while the actual work has to be done in and by 

the South. 

The will has to exist, to have a relevant impact on the local community and to develop a clear 

vision of the future. 

Soil is a key natural resource which requires better management to support sustainable 

development and to preserve this basic commodity for future generations. There is a need for 

well trained soil professionals with a sound scientific understanding of soil systems, but who 

can also develop policy and provide practical advice and guidance.

Welcome 

As soil experts, you are aware of the fact that to get off the ground – you have to know the 

ground you walk on, and you have to see what something is worth on the ground. 

In the course of this day, several speakers will take the word with no other purpose than to 

inform you about several existing possibilities to find support and to establish co-operation, 

and this at different levels and scales. In the course of this week, there will be plenty of 

occasions to meet and to refresh contacts, both with staff from the International Course 

Programme in Physical Land Resources and with your colleagues from the South. I hope that 

you will grasp this golden opportunity with both hands. 

I sincerely wish to thank here the Flemish Interuniversity Council, and in particular the 

University Development Cooperation Section, for its financial support to the promoters of the 

International Course Programme Physical Land Resources to organise an event like this. 

While the course programme provided you with the intellectual luggage, a workshop like this 

is intented to prospect channels for carrying that luggage to your targets, yet staying down to 

earth and touching ground. Above all, the International Centre for Physical Land Resources 

aims to act as a two-directional gateway for knowledge exchange. 

To conclude, I hope that you will leave no stone unturned and cover a lot of ground the 

coming days, so that you come in sight of fine land. I think this is the most I can wish to sons 

and daughters of the soil. 

Prof. P. Van Cauwenberghe

Welcome 

Opening Address by Ms. K. Verbrugghen, Director of VLIR- 

University Development Co-operation Section 



Dear Alumni, 




It is my pleasure to be given the opportunity to say a few words to you. 

First of all, I want to congratulate you all, not only for the fact that quite years ago you were 

selected as VLIR scholar out of, in many cases, hundreds of quality applications, proving your 

quality standard already at that stage, but also for the fact that you all succeeded and obtained 

a Master degree, and indeed returned to your home countries. 

Now you have all been called back to Belgium, for a number of reasons. First of all, to update 

your scientific knowledge of the field of study, physical land resources, to exchange 

information and experience and specific cases. 

This will allow you to be better equipped for your own job back home, but this will also allow 

the course organisers in Belgium to further improve their training programme. We want to 

learn from you, on the basis of your experience, how the training programme can be improved 

in terms of quality as well as of development relevance. 

Furthermore, integrating your experiences and cases into the training programme will allow 

also the other students from Belgium or elsewhere to get access to this valuable information. 

So this will contribute to the quality and the relevance of the training programme, both for the 

southern but also the northern students. 

But your being here will also allow you to improve your own network, first of all with the 

course organisers in Belgium, but also with your colleague graduates. So do talk to one 

another. Exchange business cards. Initiate long-lasting partnerships across frontiers. Because 

academic cooperation consists of both north south but also south south cooperation. 

And then finally you will be given more information on the opportunities that VLIR is 

providing. 

I am proud to be able to announce that this refresher course, organised by Ghent University, is 

co-financed by VLIR. For us, the result of an international course is not obtained by you 

getting your Master degree. No, we want you to go back home, to your home institution, and 

to make the difference there, by applying the knowledge that you acquired here, by passing on 

the knowledge to colleagues and peers, by training others. Only then, the intervention by 

VLIR, our funding, will be a good investment from the perspective of development 

cooperation. Our baseline is : sharing minds, changing lives. It is our common responsibility, 

also yours, to join brains and forces to help and improve the quality of life in the south.

Welcome 

This afternoon, my colleague Frank will elaborate more on the wide range of funding 

opportunities that VLIR is providing. Over the last years, we have added quite many new 

opportunities, so we will be happy to give you an overview. He will also briefly touch upon 

the opportunities offered by other institutions in Belgium that are involved in development 

cooperation. Maybe there is something in it for you! 

But please, remember one thing: VLIR does not directly fund individuals or organisations in 

the south. We fund cooperation between individuals and universities or research institutions in 

the south, and one or more Flemish universities. We want you to occupy and to continue to 

occupy a key or strategic position in your home country from where you can contribute to the 

development of your country, through science, and we want you to link up with our Flemish 

scientists. If those two conditions are fulfilled, we will happily look forward to receiving 

proposals from your side. 

I once again thank the organisers of this event, and prof. Van Ranst in particular, for the time 

given to me today, and I wish you all the best. Let’s keep in touch! 

Ms. K. Verbrugghen

Welcome

Opening Lectures 

OPENING LECTURES 

Sustainable Land Management in Ethiopian Highlands 

Mitiku Haile 

New Challenges of Soil Science to Food Security with Special 

Reference to China 

Tang Huajun, Zhou Wei 

Works on Erosion Processes under Wind-Driven Rain Conditions in I.C.E 

Gunay Erpul, Donald Gabriels 

1


SUSTAINABLE LAND MANAGEMENT IN THE ETHIOPIAN 

HIGHLANDS 

1.1 Development situation and policy 

1.1.1 General 

Mitiku Haile 

Mekelle University, Mekelle, Ethiopia 

1. INTRODUCTION 

Ethiopia is an agrarian country with 85% of the population earning their livelihoods from 

agriculture. It is one of the poorest countries in the world with a GDP of US$110 per capita 

per annum and 45.5 % of the population is below the poverty line. The country has suffered 

repeated famines over the last half century, and agriculture has failed to generate capital for 

diversifying and transforming the country’s economy. Hence reducing poverty through 

improving rural production and livelihoods is central to the country’s development agenda. 

There have been a number of policy initiatives since the present government which 

came to power in 1991 has sought to address these issues. The overall guiding framework 

initially developed and still adhered to is ADLI, Agricultural Development Led 

Industrialization . This sees increased production in the rural areas as critical for generating 

the materials, market base, surplus labor, export earnings and capital for industrialization. In 

2002, along with most developing world countries and in response to the identification of 

poverty reduction as the key target in the millennium development goals, the government 

developed its own poverty reduction strategy paper (PRSP) entitled the “Sustainable 

Development and Poverty Reduction Programme” (SDPRP). In 2005 this was superseded by 

an updated SDPRP called the “Plan for Accelerated and Sustainable Development to End 

Poverty” (PASDEP). This provides guidance for the second five years of the PRSP process. 

The other guiding document is the Federal Government’s Rural Development Policy and 

Strategies launched in 2003. 

The emphases in these three documents respectively are as follows: 

SDPRP seeks to: 

� support ADLI by generating a primary surplus to fuel growth in other sectors, 

� use (option) menu-based extension packages to enhance farmer choice of technologies, 

� undertake investment in education to overcome critical capacity constraints, 

� increase from 4m to 6m the households covered by Extension Packages, and 

� support agricultural research, water harvesting and small-scale irrigation. 

Rural Development Policies includes: 

� crop intensification in high rainfall areas, 

� livestock improvement and water resource development in pastoral areas, 

� water harvesting and lands conservation in drought-prone areas, and 

� livestock improvement through improved breeds and technology. 

2


PASDEP aims to: 

� capture the private initiative of farmers and support a shift to diversification and 

commercialization in agriculture, 

� support pro-poor subsistence farming where the aim is to increase crop yields for 

domestic use and to ensure food security, 

� provide intensified extension support at the kebele level to facilitate innovation. 

In all these policies the need for skilled staff and for innovations based on farm-tested 

research findings are present. It is in this way that higher education and research from the 

agricultural faculties of universities can contribute to rural development, poverty reduction 

and the country’s achievement of the Millennium Development Goals. To this end Faculties 

of Agriculture, Junior Colleges and Training and Vocational Education Centers are engaged 

in adressing issues of sustainable land management as a basis for increased productivity. 

1.1.2 Higher Education's Role in Development 

Tertiary education plays a key role in the economic and social development of any nation. 

This is particularly the case in today's globalizing, information and knowledge-based 

economy. No country can expect to successfully integrate into, and benefit from, the 21st 

century economy without a well-educated workforce. The task of integration is particularly 

great for countries like Ethiopia given the low level of education attainment of the country’s 

labor force, and the urgent need for sustained economic growth in order to reduce poverty. 

Furthermore, there are few higher education institutions with the skills, equipment and 

mandate to generate new knowledge and to adapt knowledge developed elsewhere to the local 

context. 

1.1.3 Education Policy 

Ethiopia adopted an Education and Training Policy in 1994. The policy encompasses general 

and specific objectives, as well as implementation strategies that include formal and nonformal 

education, from kindergarten to higher education. Emphasis is placed on the 

development of problem-solving capacities, with a particular focus on the acquisition of both 

theoretical and practical knowledge. 

The long-term aim is to achieve the goal of universal primary education by the year 

2015. The strategy developed to implement the policy calls for sustained public investment 

programme through the mobilization of national and international resources. The policy seeks 

to develop synergy between education, training, research and development through 

coordinated participation by relevant organizations. 

One outcome of this policy was the formulation of a sector-wide approach. The first 

Education Sector Development Programme was launched in 1996/1997 and was completed 

five years later in 2001/2002. The second five year Education Sector Development 

Programme became operational in 2001/2002, overlapping slightly with the first one, and was 

concluded in 2005/2006. The major components of the programmes were to: (1) increase 

enrolment; (2) improve leadership and management; (3) ensure quality and relevance; (4) 

improve institutional efficiency; and (5) provide a logistic framework. 

For about five decades the country had only two universities (Addis Ababa and 

Alemaya). As the primary and secondary education facilities increased, these institutions were 

unable to provide enough opportunities for quality higher education to the growing numbers 

of school leavers. In addition, the tremendous increase in the participation rate in primary and 

secondary education resulted in increased demands for qualified teachers at the various levels. 

3


To partially meet these growing demands, the country was obliged to expand the higher 

education sector. As a result, the sector witnessed rapid expansion between 1997 and 2001 

with the establishment of Bahir Dar, Debub (Awassa), Jimma, and Mekelle universities. This 

involved amalgating existing colleges in these towns. Further, to meet the growing need for 

qualified manpower by various sectors of the economy, professional programs were 

developed in business, education, engineering and health in Alemaya, Arba Minch, Dila, 

Jimma and Mekelle. The next five years saw the realization of three additional universities, 

namely Arba Minch, Gonder and Adama, by upgrading Arba Minch Institute of Water 

Technology, Gonder College of Health Sciences and Nazareth College of Technical Teacher 

Education, respectively. This brought the number of public sector universities to nine. At the 

present point in time, there are 12 new universities being established in Dessie, Debre Berhan, 

Debre Markos, Nekemt, Bale-Robe, Sodo, Dilla, Mizan Teferi/Tepi, Jigjiga, Semera, Dire 

Dawa and Axum. 

Expansion is not limited to increasing the number of higher education institutions, but 

also involves enlarging the number of academic programs they offer and their student intake. 

This has resulted in a tremendous increase in the participation rate in higher education. Within 

nine years, higher education enrolment in regular programs has increased from about 42,100 

in 1997 to 103,500 in 2005 - an increase of 146 percent. 

In addition to the expansion in terms of institutions, programmes and student numbers, 

higher education is undergoing rapid transformation in other respects. Cognizant of the fact 

that expansion needs to be supported by improvements in the management and operation of 

the higher education system, the Government has embarked upon an overall reform 

programme. This is part and parcel of the Civil Service Reform Programme the country has 

been implementing over the last few years. This requires organizations to become resultorientated, 

rather than input-oriented. The most important components of this transformation 

for higher education are: improving leadership, governance and management, and creating an 

enabling culture to provide appropriate tertiary level education. Relevance of the programmes 

to the economic development priorities of the country, as well as efficiency and effectiveness 

in the delivery of education and the use of scarce resources, are core areas of concern in this 

transformation. 

Experience shows that “massification” at an unprecedented scale can lead to 

deterioration in quality. Realizing this, the Government established, in 2003, an autonomous 

body called the Higher Education Relevance and Quality Assurance Agency to make sure that 

appropriate and effective teaching support and learning opportunities are provided for 

students. It is responsible for internal audit undertaken by the institutions themselves and 

external audits which the Agency itself carries out. The audits assess the institutions' system 

of accountability and internal review mechanisms to ensure that each institution's quality 

assurance process complies with accepted standards. In addition to this Agency, a Higher 

Education Strategy Centre was established in 2003 to formulate policies as well as devise 

strategic directions for the higher education sector. 

Sustainable land management as a course is provided in the universities and other 

colleges to enable graduates perceive the processes of land degradation and also design 

mitigating solutions.Cognizant of the fact, the extension packages of the agricultural and 

natural resources management sector have been improved to incorporate soil and water 

conservation practicies not only as a community endeavour but also as a farm management 

tool within households. 

4


2. ENVIRONMENTAL CHARACTERISTICS 

Ethiopia, with a population of 76 million people and annual growth rate of 2.36%, is the 

second largest country in sub-Saharan Africa. It has a surface area of 1.12 million km² and an 

average population density of 62 persons per km². The elevation of the country varies from 

120 m below sea level at Dalool to 4620 m.a.s.l. at the Ras Dashen Mountain. As a 

consequence the country is endowed with diversified agro-ecologies, soil types and 

biodiversity. 

The country is divided into two major physiographic regions, the highlands and the 

lowlands (Table1). This physiographic separation is based on the traditional altitudinal 

classification of the country ([20]). The lowlands which constitute more than 60% of the land 

mass are found in areas 1,000 10-14 

Kur (very cold or alpine) >3,700 >1,000


concentration of around two- thirds livestock herd of the total 78 million population - the 

largest in Africa. According to [4], the crops grown in the country are cereals (70%), pulses 

(10%), and perennials (20%). The specific crops include: tef (Eragrostis tef), maize , wheat, 

barley and , sorghum as well as coffee and enset (Enset ventricosum). 

The wide ranges of topographic and climatic factors, parent material and land use have 

resulted in extreme variability of soils in Ethiopia (Table 2). In different part of the country, 

different soil forming factors have taken place. Assessments of the nutrient status of 

Ethiopian soils indicate ranges of 0.9 -2.9 g nitrogen (N) and 0.4 -1.10 g phosphorus (P) per 

kg of soils ([7]). 

Soil type Area (km 2 ) Percent 

Acrisol 55,726.5 5.0 

Cambisol 124,038 11.1 

Chernozems 814 0.07 

Rendzinas 16,348 1.5 

Gleysols 5,273.5 0.47 

Phaeozems 32,551 2.9 

Lithosol (Leptosols) 163,185 14.7 

Fluvisols 88,261.5 7.9 

Luvisols 64,063.5 5.8 

Nitosols 150,089.5 13.5 

Histosols 4,719.5 0.42 

Arenosols 9,024 0.81 

Regosols 133,596 12.0 

Solonetz 495 0.04 

Andosols 13,556 1.2 

Vertisols 116,785 10.5 

Xarosols 53,171 4.8 

Yermosols 34,95 3.1 

Solonchaks 47,217.5 4.2 

Table 2. Distribution of soil types in Ethiopia 

Ethiopia is endowed with vast water resources with 12 major rivers and 22 natural lakes 

([24]). Professional estimates indicate that the country has an annual surface runoff of about 

110 billion cubic meters from 12 major drainage basins ([26]), only 4% of which is used ([5]). 

Groundwater resources, the true potential of the country are not clearly known. However, it is 

widely reported that Ethiopia possesses a groundwater resource potential of approximately of 

2.6 billion cubic meters (m 3 ) ([18]). 

According to [1], of the country's estimated 112 million ha of land mass, about 66%, 

about 22% is under cultivation for production of annual and perennial crops. About 96% of 

the current cultivated areas are occupied by small holder subsistence farmers, while 

commercial farms cultivate the remaining ([3]). [26] reported that the total irrigable area from 

the 12 major basins of ca. 3 million ha.[18] estimated the potential irrigable land of ca. 3.7 to 

4 million ha. The figure is still subject to change as more reliable data are being acquired 

through accomplishment of all river basins master plan studies and with the growing 

technology for water transfer exploitation. Nevertheless. the irrigated areas generate only 3 % 

of the total field crop production. 

6


Despite the country's huge water resources potential, there is high temporal and spatial 

variability: most of the rivers in Ethiopia are seasonal and about 70% of the runoff potential 

takes place during the months of June, July and August ([27]). There is uneven spatial 

distribution of river basins that between 80-90% of Ethiopia's water resources is found in four 

river basins, namely the Blue Nile, Tekeze, Baro - Akobo, and Gibe – Omo ([18]). 

Land degradation by erosion is clearly evident throughout 7000 years of history in the 

world and it is the major cause of poverty in rural areas of developing countries. 

Studies of the effect of erosion on early civilization have shown that one of the major 

causes of the downfall of many flourishing empires was soil degradation. [2] described soil 

degradation as one of the major causes of the downfall of the ancient Axumite Kingdom. [10] 

also described soil erosion as one of the elements in the decline of civilizations of Lalibela in 

the 14th century and Gondar in the 17th century. 

Much of the land degradation is found in the highlands above 1500m (45% of the total 

country's total area) ([4]). These highlands, which are characterized by favorable 

environmental conditions, have been settled and cultivated for millennia ([13]). The Ethiopian 

highlands constitute one of the most degraded lands in Africa, if not in the world ([6]). These 

highlands are an ancient and conspicuously uplifted part of the earth's surface, which by 

virtue of their location have constantly been assailed by normal erosive forces ([4]). Morever, 

the highlands have long history of tectonic instability which has split the highland into two 

parts. [4] identified six categories of soil degradation in the Ethiopian highlands: water 

erosion, wind erosion, salinization /alkalization, and chemical, physical and biological 

degradations. 

The degradation of resources is caused by heavy pressure from human and livestock 

population, coupled with many other physical, socioeconomic and political factors 

The most pressing forms of resource degradation are the destruction of the natural 

vegetation and soil erosion by water. Deforestation has been occurring in Ethiopia for 

millennia and has accelerated during the last century ([15]). Rapid population growth, 

extensive forest clearing for cultivation, overgrazing, movement of political centers, and 

exploitation of forests for fuel wood and construction materials without replanting reduced 

Ethiopia's forest area to 16% in the 1950's and to 3.1 % by 1982 ([25]). 

The water erosion includes sheet and rill erosion, gully erosion, tunneling and land 

slides. Sheet and rill erosion is the most important erosion form in all zones and altitudinal 

belts of the Ethiopian highlands ([20]). According to the 'Global Assessment of Soil 

Degradation' map ([23]), more than 50% of the northern Ethiopan highlands suffer from 

extreme loss of top soil due to sheet and rill erosion. On this map, gulling and mass 

movements are indicated as another major problem. 

Biological degradation induced by man, such as removal of field crop residues and 

dung, overgrazing and deforestation, is widespread and severe in the highlands. However, the 

major force driving land degradation in Ethiopia is nutrient depletion of agricultural soils 

arising from complete removal of crop residues from crop fields, crop production with low 

levels of nutrient inputs and lack of adequate soil conservation practices. However, this 

argument seems to contradict with the findings of [4]. Although, [7] identified erosion as 

particular concern in the Ethiopian context as the major cause of land degradation which 

declines food crop production, [20] attribute land degradation to several interacting biophysical 

social and political attributes that demand concerted interventions not only 

maintaining soil fertilitybut also farm management practices that take sustainable land 

management into concideration. 

The physical degradation of soil throughout the highlands is commonly associated with 

the biological degradation and water erosion. It could arise from excessive tillage, 

7


particularly for tef and livestock trampling between grazing grounds and watering locations 

([4]). 

Serious chemical degradation is rarely found in actively eroding soils but more common 

in Nitosols at elevations over 2000 m a.s.l. (southwestern parts of the country). Excessive 

removal of plant nutrients can result from continuous annual crops of cereals, but is not 

significant in the highlands i.e. partly allows replacement by the arrival of nutrients in the 

groundwater moving down the landscape. The argument is that had the replenishing not been 

there, the Ethiopian highlands could have been more in a severe condition than it is now, after 

so many centuries of food production. 

Soil at a given site can be formed by three processes: the deposition of sediment by 

runoff erosion, the natural weathering of rock beneath the soil and the formation of soil at the 

surface by decaying organic and inorganic minerals caused by both natural processes and by 

cropping. The deposition of sediment involves substantially larger quantities than the 

formation of soil at in situ. It is estimated that 90% of the total erosion is deposited annually 

in the lower lying areas of the Ethiopian highlands ([4]). 

Internationally, the issue of in situ soil formation rate is controversial among scientists. 

However, the common estimates lie between 0.8 and 3 t ha -1 y -1 . It is, however, agreed that 

soil formation rate under farming is faster, and that tillage operations probably increase the 

rate of top soil renewal to around 11 t ha -1 y -1 ([4]). 

All these rates are considerably lower than the soil formation rates tentatively calculated 

for the Ethiopian highlands (from 2 to 22 t ha -1 y -1 ) from the data on temperature, rainfall, 

length of growing period, soil units, soil depth, slope gradient and land cover (FAO) working 

paper 2 (WP2) ([4]). These indicative soil formation rates increase from low levels in the 

north to high levels in the west and southwest and thereafter fall towards the boarder to 

Kenya. The patterns reflect rainfall and temperature. In other reports, a soil formation rate of 

about 10 t ha -1 y -1 is estimated for the Ethiopian highlands, depending on slope gradient and 

land use type ([21, 8]). 

[9] extrapolated soil formation rates for the different agro-climatological zones of 

Ethiopia (Table 3). These soil formation rates are mean rates, taking into account rain and 

temperature conditions, however, it did not consider lithology. Over all, the data on soil 

formation rates in Ethiopia are inconsistent; on the other hand, those data are used for 

comparison with the soil loss rates. It is, however, suggested that those data should not be 

applied to the vast areas where the soil mantle results from sediment deposition rather than 

from pedogenesis ([8]). 

8


Agro-Climatogical zone Altitudinal limits (m a.s.l.) Soil formation rate 

(t ha-1 y-1) 

High Wurch(Kur) >3700 2 

Wet Wurch 3200 -3700 4 

Moist Wurch 3200 -3700 3 

Wet Dega 2300-3200 10 

Moist Dega 2300 -3200 8 

Wet Woina Dega 1500 – 2300 16 

Moist Woina Dega 1500-2300 12 

Dry Woina Dega 1500 -2300 6 

Moist Kolla 500-1500 6 

Dry Kolla 500 -1500 3 

Berha, Desert


The value reported by [22] is lower by a half than the estimate made for the Ethiopian 

highlands by [4]. The two studies are not only differing in the magnitude of the SSY but also 

in their approach and assumptions. The [4] approach was based on agro-ecologies and the 

contribution of gully erosion and other forms of erosion were ignored. On the other hand, the 

[22] approach was catchment - based and seems to over emphasize the contribution of gully 

erosion, as it is in the same order of magnitude to that of rill erosion. Moreover, [22] predicted 

solid sediment loss that took into account the catchment area as the only explanatory variable 

for sediment yield prediction, with an r 3 (coefficient of determination) of 0.59. 

Overall, the information on sediment budget in the Ethiopia highlands is not only 

inconsistent but also inadequate to represent all the components of the mass balance equation. 

Therefore, further research is needed to understand the sediment budget taking into account 

representative river basins in the highlands of Ethiopia. 

Land cover 

Area 

(%) 

Soil loss 

(tha-1y -1 ) 

Grazing 47 5 

Uncultivable 19 5 

Crop land 13 42 

Wood land/ bush land 8 5 

Swampy land 4 0 

Former crop land 4 70 

Forests 4 1 

Perennial crops 2 8 

Total for the whole of Ethiopia 100 8 

Table 4. Soil loss rates in Ethiopia(after [9] and [20]) 

Erosion impacts can be either on-site or off-site or both. Correspondingly, the impacts can be 

conceived as positive or negative. [4] has documented that positive and negative impacts are 

merely relative terms that mainly depend on the region of interest. For instance the eroded soil 

from the Ethiopian highlands that leaves via the Blue Nile can bee seen as a negative effect 

for Ethiopia but, on the other hand , the deposited sediment in the Egypt's valley had 

increased the fertility status of the in-situ soil, which might adversely affect the Aswam dam. 

In this study, on-site impacts are related to productivity of farms caused by loss of top soil 

(loss of nutrients and organic matter), reduction of soil depth, soil crusting and sealing and 

dissection of fields. In less developed countries, on-farm economic impacts of erosion tend to 

exceed off-site impacts. This reflects the lower level of downstream infrastructure 

development, less concern about water quality and the heavy dependence of small farmers on 

natural levels of soil fertility. [14] also noted that in less developed areas the onset of 

significant erosion can lead to a pattern of rapid land degradation with declining yields and 

vegetative covers that lead to shortened fallow periods, overgrazing for further erosion and 

land degradation. 

Soil fertility depletion is developing into a major constraint to agricultural production in 

Ethiopia. The Ethiopian Highlands Reclamation Study ([4]) reported that about half of the 

Ethiopian highlands (27 million ha) was significantly degraded in 1984, out of which 2 

million hectares of agricultural land have degraded to the extent that they will not be able to 

sustain crop production in the future. However, little information exists on the relationship 

between erosion, erosion hazard, and its impact on crop productivity and associated costs. 

[19] reported that a reduction of barley yield by 25 kg ha -1 for 1 cm of soil loss was observed 

10


in a Humic Andisol in the Debre Birhan area of Northen Showa. The same study for the area 

indicated that with the soil loss rate of 66t ha -1 y -1 , the shallow soil with an average depth of 45 

cm will be completely eroded in about sixty years time while crop production will decrease 

by 35% during the first twenty years. [11] predicted that most of the cultivated land in the 

Ethiopian highlands would be entirely stripped of the soil mantel within 150 years, assuming 

an average soil depth of 60cm. In economic terms, soil erosion, which is based on the data 

provided by [4], is estimated to have cost 619 million Ethiopian Birr (ETB) by the year 1990. 

[4], however, acknowledged that (1) the cost estimate has uncertainties in that the 

relationship between soil loss and yield reduction was not documented and (2) there was 

difficulty inherent in projecting soil loss. An alternative erosion-caused soil fertility 

degradation costs analysis can be applied using a 'replacement cost' approach. The logic 

behind this approach is to calculate the loss of nutrients and put a value on it using the 

equivalent value cost of commercial fertilizer. Despite the lack of data on erosion related 

productivity loss, however, productivity loss rather than replacement cost is the most 

theoretically correct way to value resource depletion. 

In other studies, the effect of land management and land use conversion was found to 

have a significant impact on the spatial variability of soil nutrients. An improvement in soil 

physical (soil structure, soil depth) and chemical characteristics e.g. N, P and organic matter 

(OM) was observed as one is going from cultivated lands to grazing lands and then to forest 

and exclosures. The improved soil characteristics are due to a decreased erosion process along 

the same direction. These studies, however, do not to indicate the nutrient status and the 

overall nutrient balance of the soils under the different land uses. Nowadays, there is 

increasing interest on assessment of nutrient balance at field and regional scale levels. [7] 

assessed nutrient balance for N, Pav, and K at regional scale and country level using two 

different soil loss estimates by USLE and LAPSUS (landscape process Model). The values (in 

kg ha -1 y -1 ) reported were: 37.7 and 6.0 for N. 7.8 and 3.0 for Pav; and 28.3 and 4.0 for K, for 

USLE and LAPSUS soil loss estimates, respectively. In both cases, soil erosion is found to be 

the prime responsible factor for nutrient depletion i.e. accounts for loss of 70%, 80% and 63% 

for N, Pav and K, respectively. In their calculation, however, they assume a constant 

enrichment ratio (ER) of 1.5 for all nutrients. 

[8] studied the N balance in Gobo Deguat (within this study region) at farmers' field 

using the Nutrient Monitoring Model (NUTMON), and estimated N loss by erosion at 12.6 kg 

ha -1 y -1 and the N balance is negative. However, an organic input from purchased manure and 

feeds that takes the highest proportion (34.2 kg ha -1 y -1 ) seems exaggerated. Moreover, the 

role of erosion in nutrient outflow is in the fourth place after harvested products (22.9) kg ha - 

1 y -1 ), crop residue in manure (13.2 kg ha -1 y -1 ), gaseous losses (4.9) kg ha -1 y -1 ), which seems 

contradicting with the work by [7] at national and Regional States level. 

Nitrogen and phosphorus balances analyzed under five different land uses in southern 

Ethiopia were either in equilibrium or positive in most of the farm components which may 

seem opposing to the findings by [8] and [7] who found strong negative balances of the 

respective nutrients. 

The information on the nutrient balance shows that there are uncertainties in the nutrient 

balance calculation which could be associated to lack of measured input and output data and, 

therefore, merits further study. Erosion and sedimentation estimates were rough in all cases as 

both were only estimated but not measured at the site. Therefore, detailed investigation of the 

erosion and sedimentation component is required in all scale of nutrient balance studies in 

Ethiopia. 

Off-site impacts include higher turbidity in rivers, lakes, reservoirs and sediment 

deposition in these same environments and flood plains. Also increased downstream runoff 

and flooding as a result of reduction of soil infiltration by the on-site impacts. Sediment 

11


delivery to river channels is probably one of the most problematic off-site consequences of 

soil erosion and it is a disturbing problem in countries of northern Africa . The inputs of the 

sediment by erosion process into rivers, reservoirs and ponds results in high sediment 

deposition rates and frequent dredging operations. 

In Ethiopia, scientific documents on the off-site impacts are very rare. [26] found that 

the increased abnormal flooding in the downstream position of the Baro Akobo river basin is 

associated with human interference within the catchment, which is due to absence of proper 

land use planning. The increased human activity is due to the increased population after the 

1984 resettlement program. These days, the abnormal flooding has become frequent also in 

places of lower Awash and in Wabishebele River Valleys which has been displacing many 

inhabitants and damaged the surrounding land. 

Efforts to rehabilitate the degraded highlands through soil and water conservation were 

going on in and promising results are being documented. Several hectares of farm lands are 

conserved and millions of tree seedlings have been planted. However a national scheme is not 

designed to measure in either biophysical and economic terms, the impact of such an effort. 

Fragmented and uncoordinated studies are undertaken with no standardized methods and with 

no possibilities to formulate a national or regional database. Policy and operational guidelines 

are required to document the scattered studies within a framework of integrating sustainable 

land management into the farm management practices by farmers. 

REFERENCES 

[1] G. Bikora. "Food security challenges in Ethiopia. Unit Nations", African Institute for Economic Development 

and Planning, Dakar, Senegal, (2001). 

[2] K.W. Butzer. "Rise and Fall of Axum, Ethiopia: a geological interpretation", American antiquity, 46 (3), 

471-495, (1981). 

[3] EPA. "National Action Programme to Combat Desertification", Environmental Protection Authority, Addis 

Ababa, November 1998, p. 158, (1998). 

[4] FAO. "Ethiopian Highlands Reclamation study", vols. 1 and 2. Food and Agricultural Organization of the 

United Nations, Rome, Italy, (1986). 

[5] FAO. "Small scale irrigation consolidation project preparation report", Food and Agricultural Organizations 

of the United Nations, Rome, Italy, (1994). 

[6] E. Feoli, Vuerich, L., Zerihun, W. "Evaluation of environmental geomorphological, erosion and socioeconomic 

factors", Agriculture, Ecosystems and environment , 91 (1-3), 313-325, (2002). 

[7] A. Haileselassie, Priess J., Veldkamp, E., Teketay, D., Lesschen, J.P. "Assessment of soil nutrient depletion 

and its spatial variability on stallholder’s mixed farming systems in Ethiopia using partial versus full nutrient 

balances", Agriculture, Ecosystem and Environment, 108, 1-16, (2005). 

[8] H. Hengsdijk, Meijerink, G.W., Mosugu, M.E. "Modeling the effect of three soil and water conservation 

practices in Tigray, Ethiopia", Agriculture, Ecosystems and Environment, 105, 29-40, (2005). 

[9] H. Hurni. "Soil formation rates in Ethiopia", Addis Ababa, FAO/Ministry of Agriculture. Joint Project EHRS, 

working paper No. 2, (1983). 

[10] H. Hurni. "Options for steep land conservation in subsistence agriculture". In: subsistence agricultural 

systems. Workshop on soil and water conservation on steep lands, San. Jau, Paurto Rico, Marsh 22-27, p. 14, 

(1987). 

[11] H. Hurni. "Land degradation, famine and land resource scenarios in Ethiopia". In:D. Pimentel (ed.), World 

soil erosion and conservation, pp. 27-62. Cambridge University Press, Cambridge, UK, (1993). 

[12] IFPRI/CSA. "Atlas of the Ethiopian Rural Economy", International Food Policy Research Institute and 

Central Statistics Agency. Addis Ababa (2006). 

[13] J. McCann. "People of the plow: an agricultural history of Ethiopia, 1800-1900", University of Wisconsin 

Press, Madison, USA, (1995). 

[14] S. McIntyre. "Reservoir sedimentation rates linked to long term changes in agricultural land use", Water 

Resources Bulletin, 29 (3), 487-495, (1993). 

[15] J. Moeyersons, Nyssen, J., Poesen, J., Deckers, J., Haile, M. "Age and backfill/overfill stratigraphy of two 

tufa dams, Tigray Highlands, Ethiopia: Evidence for Late Pleistocene and Holocene wet conditions", 

Palaeography, Palaeoclimatology, Palaecology 230, 165-181, (2006). 

[16] P.A. Mohr. "The geology of Ethiopia", Univ. College Addis Ababa Press, (1962). 

12


[17] P.A. Mohr. "The geology of Ethiopia", Addis Ababa: Haileselassie-I University Press, (1971). 

[18] MoWR. "Abay River Basin Integrated Development Master Plan Project Phase II". Data collection site 

investigation survey and analysis. Section II. Sectorial studies Vol. V Water Resources Development. Part I 

irrigation and Drainage. Ministry of Water Resources, Addis Ababa, Ethiopia (1998). 

[19] T. Mulugeta. "Soil conservation experiments on cultivated land in Maybar area, Wollo region, Ethiopia". 

SCRP, Research Report 16, (1988). 

[20] H. Mitiku, Herweg K., Stillhardt, B. "Sustainable Land Management:New Approaches to Soil and Water 

Conservation In Ethiopia", Berhanena Selam Printing Enterprise. Addis Ababa, p. 304, (2006). 

[21] E.J. Mwendera, Saleem Mohammed, M.A. "Hydrologic response to cattle grazing in the Ethiopian 

Highlands", Agriculture, Ecosystem, Environment 64, 33-41, (1997). 

[22] J. Nyssen, Poesen, J., Moeyersons, J., Deckers, J., Mitiku Haile, Land, A. "Human impact on the 

environment in the Ethiopian and Eritrean highlands-a state of the art", Earth Science Reviews 64 (3-4), 273- 

320, (2004a). 

[23] L.R. Oldeman, Hakkeling, R.T.A., Sombroek, W.G. "World map of the status of human induced soil 

degradation": An explanatory note, 2 nd ed., p 27. Wageningen and Nairobi: ISRIC and UNEP, (1991). 

[24] T. Tarekegn. "The role of water harvesting, small, medium and large scale irrigation in the overall 

agricultural production system and rural development", A paper presented on the first National Water Forum in 

Ethiopia October 23-24, Addis Ababa Ethiopia, (2004). 

[25] UNEP (United Nations environment Programme). "Ecology and Environment:What Do We Know About 

Desertification", Desertification Control, 3, 2-9, (1983). 

[26] M. Woube. "Flooding and sustainable land-water management in the lower Baro-Akobo river basin, 

Ethiopia", Applied geography, 19, 235-511, (1999). 

[27] E. Yazew. "Development and management of irrigated lands in Tigray". PhD Dissertation, UNESCO-IHE 

Institute for Water Education, Ethiopia, p. 284, (2005). 

13


NEW CHALLENGES OF SOIL SCIENCE TO FOOD SECURITY 

WITH SPECIAL REFERENCE TO CHINA 

Abstract 

Tang Huajun & Zhou Wei 

Institute of Agricultural Resource and Regional Planning, Chinese Academy 

of Agricultural Sciences, Beijing-100081, China 

As the main productive resource for agriculture, soil is one of the most basal factors consisting of comprehensive 

ability for food production, and the base and assurance for food security in China. In the situation that arable 

land is decreasing drastically, the protection of soil resource has become a major factor affecting sustainable 

development of the country. Preliminary investigations mainly focused on relationship between amount of arable 

land and food demand in China, but lack of systematic analysis on soil resource security associated with food 

demand and agricultural product quality. In this paper, based on investigation of the changes in quantity and 

quality of soil resource in China, the relationships between soil resource and food quantity security and quality 

safety were discussed, and policy options for keystone basic research tasks and engineering counter-measures 

were also proposed. 

INTRODUCTION 

China has very abundant soil resource with many kinds of soil types. The total land area is 9.6 

million km 2 . Climate types ranges from tropical zone to cold-temperate zone and from humid 

region to arid region. There are 14 soil orders, 39 suborders, 138 soil types and 588 subtypes 

in the whole country (Gong et al., 2005). The area of Cambosols and Aridosols occupies more 

than 20% of total soil area, that of Histosols, Ferralosols, Vertosols, Andepts and Spodosols 

accounts for 1%, the other includes Anthrosols, Halosols, Gleyosols, Isohumosols, Ferrosols, 

Argosols and Primosols (Table 1). Moreover, the absolute amount of cultivated land, 

woodland and grassland ranks number 4, 8 and 3 in the world, respectively. The data are 

based on 1:12,000,000 soil map, soil classification is from Chinese Soil Taxonomy. 

Soil orders Percent total soil area Soil orders Percent total soil area 

(%) 

(%) 

Histosols 0.22 Isohumosols 8.67 

Anthrosols 4.84 Ferrosols 8.89 

Ferralosols 0.44 Argosols 7.42 

Vertosols 0.30 Cambosols 21.51 

Aridosols 23.01 Primosols 9.76 

Halosols 3.64 Others 0.04 

Gleyosols 1.24 

Table 1: Soil resources inventory of different soil orders in China 

The amount of arable land per capita in China is very limited. The total arable land area is 

about 1.26×10 8 hm 2 , with arable land area per capita of 0.1 hm 2 , less than 40% of the average 

in the world (Zhao et al., 2006). Figure 1 shows that the amount of arable land resource has 

decreased dramatically since 1996, and this tendency will be continued. The main factors 

resulting in such a decrease of cultivated land include industrial construction, calamity 

damage, ecological returning and planting structure readjustment (Table 2), accounting for 

14


15.68%, 5.73%, 61.43% and 17.16% of the total loss of arable land, respectively. Thus, 

ecological returning among various factors dominates land loss. In addition, the uncultivated 

soil resource which can be available to agricultural production in China is about 0.133×10 8 

hm 2 , less than 6% of the total arable land area, a serious shortage of farmland resource in 

China is coming (Smil, 1995; 1999). 

Area of cultivated land (×10 4 hm 2 ) 

13200 

13000 

12800 

12600 

12400 

12200 

12000 

11800 

Area of cultivated land 

Grain production 

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 

Year 

Fig 1: Changes of the cultivated land and grain production from 1996 to 2005 in China 

Year Construction Damage Returning Readjustment Sum ofdecrease 

1997 1.930 0.470 1.630 0.590 4.620 

1998 1.762 1.595 1.646 0.701 5.704 

1999 2.053 1.347 3.946 1.071 8.417 

2000 1.633 0.617 7.628 5.782 15.66 

2001 1.637 0.306 5.907 1.083 8.933 

2002 1.965 0.563 14.26 3.490 20.27 

2003 2.610 0.500 22.37 3.310 29.79 

2004 2.928 0.633 7.329 2.047 12.94 

Sum 16.52 6.032 64.71 18.07 105.3 

Average 2.065 0.754 8.089 2.259 13.17 

Table 2: Structural analysis of changes in cultivated land in China from 1997 to 2004(×10 4 hm 2 ) 

The geographic distribution of soil resource, food production and population is uneven in 

China (Gong et al., 2005). The southeast region with humid climate and 41.6% of the total 

land area, contains 81% of the population in China, 72.2% of the arable land, 81.5% of the 

total grain production of China, but with increasingly eminent problems such as people-land 

confliction and environment deterioration; Northwest region with arid climate and 35.7% of 

the total land area, contains 4%, 8.2% and 4.2%, respectively. Due to restriction of aridity and 

cold climate to agricultural production and life of human being, there is a sharp confliction in 

water and soil, a fragile environment, an undeveloped economy, and a less population and 

cultivated land in this region; Central region with semi-humid climate and 22.7% of the total 

land area, accounts for 15% of the population in China, 19.6% of the cultivated land, 14.8% 

of the total grain production in China (Table 3). 

15 

5200 

5000 

4800 

4600 

4400 

4200 

4000 

3800 

Grain production ( 10 5 t)


Zones Percent total 

population 

(%) 

Percent 

total soil 

area (%) 

16 

Percent total 

land area (%) 

Percent total 

grain production 

(%) 

Total 100 100 100 100 

I Humid zones of southeast 

China 

81.0 41.6 72.2 81.5 

1 Cold-temperate zone 0.04 1.2 0.1 0.1 

2 Mid-temperate zone 6.96 8.6 16.3 13.7 

3 Warm -temperate zone 19.7 5.2 15.7 20.5 

4 North subtropical zone 15.7 4.3 11.5 15.2 

5 Central subtropical zone 28.7 17.0 22.4 26.1 

6 South subtropical zone 8.4 4.3 4.9 4.9 

7 Tropical zone 1.6 1.0 1.3 1 

II Semi-humid zones of 

central China 

15 22.7 19.6 14.8 

1 Mid-temperate zone 2.0 6.0 4.2 2.5 

2 Warm-temperate zone 9.0 6.2 10.8 7.9 

3 Plateau temperate zone 4.0 10.5 4.6 3.9 

III Semiarid and arid zones 

of northwest China 

4.0 35.7 8.2 4.2 

III 1 Mid-temperate zone 1.1 8.2 2.9 1.5 

III 2 Warm-temperate zone 2.22 12.4 4.4 2.2 

III 3 Plateau temperate zone 0.49 5.0 0.7 0.5 

III 4 Plateau temperate zone 0.08 2.0 0.11 0.0008 

III 5 Plateau sub- frigid zone 0.05 5.3 0.06 0.0005 

III 6 Plateau frigid zone 0 3.0 0 0 

Table 3: Soil regionalization of China 

CHANGES IN QUALITY OF SOIL RESOURCE IN CHINA 

Deterioration of soil resource 

Soil erosion leads to deterioration of arable land quality, such as reduction in the thickness of 

soil layer, damage of soil structure and loss of soil nutrients. According to estimation, due to 

water loss and soil erosion, annual loss of soil substance, organic matter, N, P and K is about 

5.0×10 9 t, 2.7×10 7 t, 5.5×10 6 t, 6.0×10 3 t and 5.0×10 6 t, respectively (Pan,2005). 

Soil desertification and sandification occurs seriously. According to Station of 

Desertification Communique of China in 2005, the total area suffered from desertification is 

2.64×10 6 km 2 until 2004, accounting for 27.46% of the total land area; That suffered from 

sandification is 1.74×10 6 km 2 , accounting for 18.12% of the total land area; The amount of 

cultivated land suffered from sandification is 4.63×10 4 km 2 , of which occupies 2.66% of total 

sandification land (Ministry of Forestry P.R.C, 2005). Wind erosion of surface soil with 

abundant nutrients results in decline of soil fertility, damage of soil physical structure, decay 

of production ability and degeneration of farmland quality. 

Arable land productivity is being degenerated. Among the existing arable land, highproductive 

land accounts for 21.5%, intermediate-productive land 37.2%, and low-productive 

land 41.2% (Table 4). Soils with the organic matter content of 1% to 2% and lower than 1% 

accounts for 38.3% and 26.0%, respectively. The situation of soil nitrogen content is similar


to that of organic matter, and soils with total nitrogen content of 0.1 % to 0.075 % and lower 

than 0.075% accounts for 21.3% and 33.6%, respectively. As a whole, the total N content is 

relatively low. Cultivated land with phosphorous, potassium, sulfur and micronutrients 

deficiency accounts for 59%, 30%, 30% and 50%, respectively (Table 5). The soil physical 

properties tend to be deteriorated, 40%, 35% and 25% of low-productivity paddy field is 

Gleyed soil, illuvial hardened soils and heavy hardened soil, respectively. 

High productive land Interm productive land Low productive land 

Standard 

(t/hm 2 Percent Standard 

) distribution (t/hm 2 Percent Standard 

) distribution (t/hm 2 Percent 

) distribution 

Rice >6 21.5% 

3~6 37.2% 5 2.5~5 5.2 

2.3~5.2 


2005. The three-year-result of monitoring on agricultural soil quality in Zhujiang delta 

regions showed that the soils are contaminated by heavy metals such as Hg, Cd and As, and 

petroleum. The contaminated area accounts for about 50% of total soil area in these regions, 

of which light contaminated area is 32%, middle contaminated area is 8%, and heavy 

contaminated area is 10% (Wan et al., 2005). 

Central China has a large proportion of low-productivity farmland, in which soils are 

relatively infertile. In the past 20 years, soil organic matter, N, and P content tended to 

increase, but the proportion of various nutrients was imbalance, and soil available K was 

seriously depleted. The ratio of soil productivity to application rate of chemical fertilizer 

tends to decrease with development of intensive cropping. 

Semiarid region in Northwest China is seriously subjected to soil erosion. The land area 

with soil erosion in Loess Plateau is 1.13×10 7 hm 2 , accounting for 24.85% of the total area 

with soil erosion in China. The land area with sandification in the northwesten arid region and 

Loess Plateau accounts for 21.06% and 10.70% of the total soil area with sandification in 

China, respectively (Li, 2002). In addition, soil nutrients are generally found to be deficient in 

these regions. 

In Central China and Southwest China, acid rain is always one of important factors 

resulting in soil acidification and degradation of soil quality. Acid rain not only directly 

influence crop adaptability to low soil pH, but also accelerate leaching and loss of soil 

nutrients, such as Cu and Zn, which lead to greatly decline of soil productivity and fertilizer 

use efficiency (Zhao, et al., 2002; Galloway, 2001). 

SOIL RESOURCE AND FOOD SECURITY IN CHINA 

The decrease of cultivated land area in China greatly affects food production. Total food 

production tended to decline from 1998 to 2003, and began to ascend since 2004 (Fig 1). In 

order to ensure the country's security of grain supply, it is essential to increase production per 

unit area. It is estimated that the food deficit in the coming years 2010, 2030 and 2050 would 

be expanded to 5,127×10 4 t, 7,359×10 4 t and 1,354×10 4 t (Zhao et al., 2002), respectively. 

Difference between the present cultivated land area and the minimum requirement in these 3 

phases will be over 900×10 4 hm 2 , and the pressure index of cultivated land will be more than 

1.0 (Table 7). Thus, China will have a big challenge in feeding its growing population with a 

declined cultivated land area. 

Soil resource and food safety 

Due to excessive and improper application of fertilizer and pesticide as well as wastewater 

irrigation, poisonous substances increasingly accumulated in both soils and crops, situation of 

food quality safety become more and more serious. It was reported that 10% of grain, 24% of 

farm animal products, and 48% of vegetables have quality safety problems in some heavy 

contaminated region (Dong & Zhang, 2003). It is worried about that the residual effects of 

some low-concentration poisonous substance may last for several decades or even several 

generations. 

18


2010 

Year 

2030 2050 

Population (100 million) 13.76 15.53 15.89 

Food demand (10 4 t ) 59177 69907 71338 

The minimum requirement of cultivated land 13426.2 12518 11673 

(10 4 hm 2 ) 

The present cultivated land area (10 4 t) 12518.14 11600.33 10749.82 

Grain production (10 4 t) 53486 61348 69684 

Food deficit (10 4 t) -5127 -7359 -1354 

The pressure index of cultivated land * 1.073 1.079 1.086 

*The pressure index of cultivated land = the minimum requirement of cultivated land / present 

cultivated land area 

Pesticide residue in food 

Table 7: Estimation of food security and cultivated land change in China 

Pesticide residue mainly occurs in grains, vegetables and fruits. According to the inspection 

results of 23 cities in China in the third quarter of 2001 issued by Quality Technology 

Supervisory Bureau of China, the pesticide residue in 47.5% of vegetables exceeded the 

maximum permitted value (Dong & Zhang, 2003). Although organochlorine pesticide have 

been prohibited for nearly 20 years, it can be detected in various crops, which is still a threat 

to human health through food chain. Investigations also demonstrated that the benzahex and 

DDT in tea and fruit could be detected, but the residual level was under standard limit (Fang, 

1998). However, it was also found that the level of organochlorine residue in 40% of the tea 

were over maximum limit value (Hao, 2001). 

Heavy metal residue in food 

Heavy metal residue in agricultural products occurs in wastewater irrigated soil in suburb of 

large and middle cities or mining area. Especially vegetables grown in suburb soils are easily 

subjected to heavy metal contamination. According to the investigation on crop quality in 

suburb of 10 province capital cities in 2000, heavy metal residue in 30% of samples in 7 cities 

exceeded the limit value. The investigation of food quality in 300, 000 hm 2 in basic protected 

farmland in China showed that heavy metal residue in 10% of samples was found to be over 

the limit value (Dong & Zhang, 2003); Vegetables grown in suburb in big cities of China 

have been contaminated by heavy metals to some extent, especially Cd, Hg and Pb. The 

standard-exceeding rate of Pb in vegetables in suburb of Xi-an is 48.0%, while that of Cd in 

Nanning is 91%, where the highest level of heavy metals in vegetables was found to be 6.2 

times more than the limit of sanitation standard(Zhang & Bai, 2001). 

Nitrate residue in food 

Nitrate residue in food mainly arises in intensive cultivation regions, especially, nitrate and 

nitrite residues in vegetables grown in greenhouse generally occur. The nitrate content in 7 

kinds of leafy vegetables in Zhujing delta area are more than 1,200 mg/kg with 100% of 

samples beyond the standard limit, and the highest level of nitrate is 5.35 times more than the 

limit value (Xie, 2000). In Xi-an, the nitrate residue in 32.5% of vegetable samples is over 

standard limit, and the highest level is 3.69 times more than the limit value (Wang, 2000). 

19


STRATEGIES FOR SUSTAINABLE UTILIZATION OF SOIL 

RESOURCE IN CHINA 

Keystone basic research tasks 

Keystone basic researches on soil degradation should be carried out with respect to soil 

obstacle factors and main problems in sustainable utilization of soil resource (Yu, 2001). 

The feature of acidity and acidification mechanism in the soil of south China 

Great attention should be paid to probe the feature of acidity and acidification mechanism in 

the soil of south China with respect to differences in soil condition and constitution of acid 

rain. The main research tasks include: (1) Fate of H + entering into soil; (2) Changes of Al 3+ 

forms and chemical equilibrium of solid-liquid interface; (3) Effect of specific absorption of 

sulfate on soil acidification; (4) Effects of soil acidification on release of poisonous elements 

and leaching loss of nutrient elements; (5) Predication of soil acidification (sensitivity of the 

main soils types to acid deposition and its buffer capacity to acidification); (6) Acidification 

features in weakly acid soil in transition zone. 

Mechanism of genesis of gleyed soil 

The gleying process occurs in three types of soils: a swamp soil waterlogged for a long term, 

a paddy soil irrigated during growth period and bottom-gley soil with a certain height of 

groundwater level. Their common feature is that all layer or one layer of soil is saturated with 

water, and then reduction occurs to produce poisonous substance. It accounts for 1/5 of the 

soils in the world and more in China. The main research tasks include: (1) The relationship 

between intensity factors and quantity factors under reducing condition; (2) Development of 

determination method for distinguishing organic reduced substance using chemical and 

electrochemical method; (3) Reaction mechanism of organic reductive substance with Fe and 

Mn and its dynamics ; (4) Changes of Fe and Mn forms and their effects on plant growth; (5) 

Physical and chemical equilibrium among H2S—S 2 —FeS and their toxicology to organisms. 

Movement characteristic of salts and alkalization mechanism in saline-alkali soil 

There is a large scale of saline soil and alkali soil in China. Current researches emphasized on 

salt geochemistry, however, little information is available on mechanisms of physical 

chemistry of salinization and alkalization. The main research tasks include: (1) the effect of 

absorption-desorption on the movement of Na, K, Ca and Mg ions in soils; (2) the effect of 

complexation reaction on mobility of salt ions; (3) Differential movement of chlorine, nitrate, 

bicarbonate, and sulfate anions caused by absorption—negative adsorption—desorption 

process; (4) The osmotic potential of soil solution and its relationship to equilibrium of 

physical chemistry of various ions between solid phase and liquid phases; (5) Physical 

chemistry factors controlling pH of alkali soil. 

Transformation of poisonous elements in soil and their toxicology to organisms 

In the recent year, there have been growing concerns in China about inorganic contaminants 

in soils, such as Hg, Cd, Cr, Pb, Cu, As, F etc. The main research tasks include: (1) Relative 

importance of specific absorption and electrochemcial absorption of heavy metal ions in 

various types of soil; (2) Effect of precipitation, absorption and complexation reaction on 

20


distribution of heavy metal ions between solid phases and liquid phases; (3) Effect of heavy 

metal ions on characteristics of soil surface chemistry;(4) Effect of concomitant cations and 

anions on distribution of As and F between solid phase and liquid phase; (5) Forms and 

activities of variable valence elements (Cr and As) under different redox conditions. 

Migration of poisonous elements and nutrient elements and their effects on groundwater 

quality 

Nutrient element or poisonous element can affect plant growth through its movement to root 

surface. These elements can also influence the quality of groundwater through a series of 

reactions during their permeation in the soil. The main research tasks include: (1) Effect of 

absorption-desorption on migration of ions in soils and its mechanism; (2) Relationship 

between specific absorption and movement speed of heavy metal ions; (3) Effect of coexisting 

ions with different charge on the migration of ions; (4) Reaction dynamics of ions in 

the interfaces among soil colloid, soil solution and root or microorganism; (5) Relationship 

between the absorption of nitrate in variable-charge soils and nitrate contamination in 

groundwater. 

The renewal mechanism of soil organic matter 

Renewal mechanism of soil organic matter has received great concern due to rapid decline of 

organic matter in black soil. The main research tasks include: (1) Changes of components and 

characteristics of soil organic matter under different moisture and temperature conditions; (2) 

Factors affecting components, mineralization rate and humification coefficient of soil organic 

matter and their mechanisms; (3) Equilibrium models for describing dynamics of soil organic 

matter and their equilibrium points in soils with different fertility; (4) Effect of organic 

materials application (straw, green manure and animal manure) on the formation and 

characteristics of soil organic matter. 

Engineering counter-measures 

Balance fertilization and organic fertilizer application 

For a long time, intensive utilization of farmland and imbalance recovery of nutrients has 

resulted in great decline of soil fertility and fertilizer use efficiency. Fertilization and nutrient 

management need to be improved. Plentiful organic fertilizer resources in China have not 

been fully used yet. It is estimated that 4 billion tons of organic substances was produced in 

agricultural system every year, such as livestock manures, green manures, straws, etc., which 

can provide about 53.16 million tons of nutrients, including 21.76 million tons of N, 8.7 

millions tons of P2O5 and 22.7 million tons of K2O. However, only 19.28 million tons of 

organic substances, or 36% of the total resources, are effectively used. The remainder enters 

into environment, and has a risk of contamination to ecological system. Therefore, it is very 

important to improve fertilizer application techniques such as balance fertilization with 

rational nutrients ratio, combined application of organic and inorganic fertilizers, to enhance 

soil fertility and ensure food security and food safety in China. 

Amelioration of soil and remediation of contaminated soil 

Since various adverse factors such as drought, sandification, salinization and acidification 

exist in cultivated lands of China, it was suggested to develop soil amelioration techniques, 

21


including increasing organic matter content of black soil, comprehensively ameliorating saltalkali 

soil, improving soil structure, neutralizing acidic soil, and optimizing management of 

fertilizer and water. 

With respect to contamination of pesticide, heavy metals and nitrate, both pollutant 

source and pollutant discharge should be controlled simultaneously. Great attention should be 

paid to both urban and rural environment protection, especially agricultural non-point source 

pollution. Studies on remediation of contaminated soils, regionally comprehensive 

ameliorating techniques, and developing patterns for sustainable utilization of cultivated land 

should be strengthened. 

Improvement of ecological environment 

High quality of farmland depends on improvement of ecological environment in China (Tang, 

2000). Although a big net of protection forest of farmland had been established in China, it is 

not enough to protect all of cultivated land countrywide. The current pivotal works should be 

emphasized on remediation of soil sandification in semiarid and semi-humid regions, 

amelioration of soil secondary salinization and alkalization, and prevention of soil erosion. In 

addition, ecological returning of cultivated land to grassland or forestland is an absolutely 

necessary measure in interleaving zone in semiarid regions and in mountainous region of 

south China. 

Exploitation of uncultivated resource 

It is an important approach to exploit uncultivated resources for compensating deficit of 

farmland resource and ensuring food security. These approaches include improve of grassland 

to feed animal to increase meat, egg and milk products, utilization of some crops straw to feed 

household animals, utilization of water resource to develop aquaculture, and development of 

forest and fruit production (Gong et al., 2005). 

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[12] F. Pan. 2005. Science Times (In Chinese), (2005). 

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Agricultural Science and Technology Press, (2000). 

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334, (2005). 

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23


WORKS ON EROSION PROCESSES UNDER WIND-DRIVEN 

RAIN CONDITIONS IN I.C.E 

Gunay Erpul 1 & Donald Gabriels 2 

1 Faculty of Agriculture, Department of Soil Science, University of Ankara, 06110 Diskapi – Ankara, Turkey 

2 Department of Soil Management and Soil Care, Ghent University, Coupure Links 653, B 9000 Ghent, Belgium. 

Abstract 

Soil erosion processes under wind-driven rains are important field of study for understanding the mechanism and 

developing prediction models. Clearly, the processes under conditions in which wind and rain act together differ 

significantly and conceptually from those under windless and rainless conditions. In this paper, wind-driven rain 

erosion research performed in I.C.E wind tunnel rainfall simulation facility was discussed and reviewed by 

analyzing the processes in place and methods to measure model parameters as influenced by horizontal wind 

currents. Additionally, concept and mechanism for rainsplash detachment and transport and sediment transport 

by raindrop-impacted shallow overland flow were given thoroughly. 

INTRODUCTION 

The installation of a rainfall simulator inside the wind tunnel of I.C.E. (International Center 

for Eremology, Ghent, Belgium) enabled to study the combined effect of wind and rain on the 

erosion processes [11]. The simulated characteristics of wind-driven rains were assessed in 

the tunnel [1,3,4]. Kinetic energy of the simulated rainfalls of I.C.E. was determined by the 

splash cup technique [2,4]. Also, a two-dimensional numerical model and a kinetic energy 

sensor were used to estimate wind-driven raindrop trajectories [10,23]. 

After the mass and energy states of the simulated rainfalls of I.C.E. were described 

under windless and wind-driven conditions, rainsplash detachment studies were commenced 

[10]. On the other hand, a series of tests conducted to assess the effect of wind velocities on 

sand detachment from splash cups [6]. 

Along with on the rainsplash detachment process, the combined effect of rain and 

wind on the rainsplash transport process was examined in depth [7] Another paper presented 

experimental data on the effects of slope aspect, slope gradient, and horizontal wind velocity 

on the splash-saltation trajectories of soil particles under wind-driven rain [9]. 

Total interrill erosion under wind-driven rain was defined as a sum of wind-driven 

rainsplash and sediment transport by rain-impacted thin flow transport, which accounted for 

the transport processes occurred before and after runoff onset, respectively [8]. A 

quantification of wind and rain interactions and the effects of wind on both transport 

processes aimed to provide an opportunity for an erosion prediction technology to improve 

the estimation in situations where wind and rain occurred at the same time. Additionally, an I. 

C. E tunnel study under wind-driven rains was conducted to determine the effects of 

horizontal wind velocity and direction on sediment transport by the raindrop-impacted 

shallow flow [5]. Wind velocity and direction affected not only energy input of rains but also 

shallow flow hydraulics by changing roughness induced by raindrop impacts with an angle on 

flow and the unidirectional splashes in the wind direction. To particularly examine the 

roughness effect of impacting raindrops with an angle on sediment transport capacity of thin 

flow, KE was divided into its components and the partitioning of the KE into two components 

provided a better insight into the processes for which they independently played a role [20]. 

24


This paper targets to give a review of wind-driven rain erosion research performed in 

I.C.E wind tunnel rainfall simulation facility. The review contains analyses of the processes in 

place and methods to measure wind and rain parameters in action. As well, concept and 

mechanism for rainsplash detachment and transport and sediment transport by raindropimpacted 

shallow overland flow are reviewed by giving research results. 

MATERIALS AND METHODS 

A description of the wind-tunnel research facility of International Center for Eremology 

(I.C.E.), Ghent University for wind, rain, and jointly wind and rain studies is given by 

Gabriels et al. (1997) [11] and Cornelis et al. (2004) [1]. Horizontal wind speeds were 

measured with a vane-type anemometer and associated recording equipment in the center of 

the wind tunnel. The reference wind velocities were determined up to 2 m and profiles for 

these velocities characterized by a logarithmic equation. In our studies, the boundary layer 

was mostly set at about 0.30 m, and subsequently, the reference wind shear velocities were 

derived from the logarithmic wind profiles by regression, assuming a fixed roughness height 

of 0.0001 for a bare and smoothed soil surface. 

In studies, the central pipe line of rainulator on the ceiling of the I.C.E. wind tunnel 

along the working area was used, where downward oriented nozzles were installed at 2 m 

high and 1 m intervals. The nozzle employed was an axial-flow, wide angle, full cone type. A 

pumping unit supplies water from a tank to the pipe and accordingly to the nozzles. The lower 

and upper limits of the operating pressures were 0.75 and 1.50 bar, respectively. The spatial 

distribution of the intensity was measured with rain gauges with 11 cm in diameter and 13.5 

cm in depth. When studies were done on inclined surfaces with different aspects, rainfall 

intensity was directly determined with the same slope degree and aspect as the sloping 

experimental set-ups. The drop size distribution was determined by an absorbent paper dyed 

with 1 M CuSO4. Colored paper was exposed to simulated rainfall in the tunnel after paper 

calibration was performed with drops of known size with known velocities. 

The energy of the simulated rains was determined by the splash cup technique [2] and 

the kinetic energy sensor [23]. Also, an analytical calculation was made to approximate the 

kinetic energy of wind-driven rains taking forces that act on a raindrop falling through a wind 

profile into account. The splash cup technique involved exposure of a cup, 8-cm in diameter 

and 4-cm in depth, packed with standard sand of 200 - 300 µm particle size range, to the 

simulated rainfall. The amount of sand, which splashed out of the cup, was a measure of 

rainfall energy. A calibration study with vertically falling raindrops was previously performed 

to establish a linear relationship between the amount of the standard sand splash and the rain 

energy. Together with splash cups, the readings of the sensit kinetic energy sensor were taken 

during runs. Similar course of actions followed in the splash cup technique was used to 

acquire different energy levels. In addition, the two-dimensional analytical model was used to 

estimate the KE considering forces that act on a raindrop falling through a wind profile. In the 

analytical approach assumed was that the reference wind velocity was the x-component of the 

rain velocity vector at the nozzle height, and the z-component was the normal terminal 

velocity in still air. 

Rainsplash detachment by windless and wind-driven rains were evaluated on the soil 

surfaces of three loess-derived agricultural soils packed into a 55-cm long and 20-cm wide 

pan placed at both windward and leeward slopes of 7%, 15%, and 20% (Figure 1). Soil 

detachment rates were determined by the amount of the splashed particles trapped at set 

distances on a 7-m uniform slope segment. For windless rain, splashboards were also 

25


positioned to collect side splash. Calculation of rainsplash detachment rate was based on the 

mathematical form of rainsplash erosion [19,21,25]: 

n 

q = ∑ mix 

i 

(1) 

i= 

1 

where, q (gm -1 min -1 ) is the total rainsplash erosion, mi (g) is the mass of a particle, which is 

splashed over a distance xi (m) measured along the x-axis. Rainsplash detachment rate was 

estimated from the area under the curves of mass with distance by: 

1 m i 

D = x 

At ∫ ∂ 

(2) 

r x i 

where, D (gm -2 min -1 ) is the rainsplash detachment rate, A is the surface area of soil pan 

2 

( 0 . 55m 

× 0. 

20m 

= 0. 

110m 

) and tr (min) is the time during which rainsplash process occurred. 

Additionally, a rainsplash detachment study was conducted with cohesionless sand 

surfaces. Windless rains and the rains driven by horizontal wind velocities of 6, 10, and 14 

ms -1 were applied to the splash cups, 8 cm in diameter and 4 cm in depth, placed flat to the 

base of the tunnel (Figure 2a) [16]. The cups with a removable porous bottom to allow free 

drainage were filled at a full level with standard graded tertiary dune sand obtained as a sieve 

fraction of 100 – 200 µm (310 gram per cup). After manually compacted by tapping, the 

surface of the sand was smoothed exactly on a level with the rim of the cup. Each run was 

performed on a pre-wetted sand surface to prevent sand from lifting off due to the wind. For 

each intensity and wind velocity level, there were 30 splash cup measurements (a total of 360 

splash cup measurements with 3 intensity and 4 wind velocity levels. Sand detachment rates 

were evaluated by the amount of sand splash out of the cup. 

26


Wind 

direction 

a) Top view 


direction 

α 

Soil pan 

b) Side view of windward setup 


direction 

α 

c) Side view of leeward setup 

θ 

Sediment traps 

7-m uniform slope segment 

Wind-driven rain 

Wind-driven rain 

27 

α: rain inclination from vertical 

θ: slope degree 

φ : angle of rainfall incidence 

cos φ = cos(α - θ) 

θ 

α: rain inclination from vertical 

θ: slope degree 

φ : angle of rainfall incidence 

cos φ = cos(α + θ) 

Figure 1. Experimental set-up with soil pan and sediment traps for rainsplash measurements, 

arranged on the slopes of windward and leeward in the I. C. E. wind tunnel.


standard sand 

Path of raindrop 

8cm 

(a) 

Sand splashes in 

all directions 

Figure 2. Splash cups used to evaluate the sand detachment rates (a), radial sand splashes by the 

vertical raindrop (b), and unidirectional sand splashes by the inclined raindrop (c). 

m 

D = (3) 

At 

where, D is the sand detachment rate (g m -2 s -1 ); m is the mass of soil (g) splashed out of the 

cup. The product of At determines the number of sand particles per unit area per unit time, 

which are raindrop-induced and entrained in the splash droplets. 

Similarly, rainsplash transport rates of soils were calculated using the amount of the 

splashed particles trapped at set distances on a 7 m uniform slope segment (Figure 1) and 

based on Eq. (1) by: 

1 

= ∫ m dx 

At 

Qs i 

(4) 

r 

where, Qs is in g m -1 min -1 2 

, A is the collecting trough area ( 1 . 20m 

0. 

14m 

= 0. 

168m 

) 

28 

4cm 

porous cloth bottom 

Path of raindrop 

(b) (c) 

α: Rain inclination from vertical 

Unidirectional 

sand splashes 

× , and tr is 

the time (min) during which rainsplash process occurred. Furthermore, using the exponential


relation between mass of soil particles and distance traveled, the average rainsplash trajectory 

was derived from the average value of the fitted function: 

b 

− 1 δx 

X = e dx 

b a ∫β 

(5) 

− 

a 

Eq. (5) gives an approximation of the average value of the mass distribution curves 

over the interval a ≤ x ≤ b, where the lower limit a = 0. β and δ are coefficients that depend 

upon the physical properties of soil particles. 

During each rainfall application and after runoff started sediment and runoff samples 

were collected at 5-min intervals at the bottom edge of the pan using wide-mouth bottles and 

were determined gravimetrically. Total sediment and runoff values, and the time during which 

the process occurred were used in calculation of sediment transport by rain-impacted thin 

flow (qs). 

RESULTS AND DISCUSSION 

Assessment of drop size distribution of simulated rainfall in the I. C. E. wind tunnel by the 

logistic growth model given as Eq. (6) indicated that a distinct increase in D50 for all 

operating pressures was observed, and values were higher than 1.50 mm [2, 3, 4]. 

100 

N ( d) 

= (6) 

−βd−γ 

1+ 

e 

where, N(d) is the cumulative percentage of a given drop size by volume, d is drop diameter 

(mm), and β and γ are parameters of the logistic growth model. Indeed, the effects of wind on 

the drop size distribution of the simulated rains of the tunnel were rather different from its 

effects on that of natural rains. In other terms, its effect on large drop sizes would not be as 

great as those on small drops. Large drops are less stable, and wind may cause some of them 

to break up into smaller drops. Consequently, disintegration of large drops depending on wind 

may actually lead to a reduction in drop size. However, the wind caused the formation of 

larger drops in the tunnel since collisions between small drops happened more frequently as 

result of their greater number per unit volume of air. This accordingly brought about an 

increase in the median drop size. 

Assessment of the spatial distribution of the rain intensity in I.C.E. wind tunnel 

showed that wind-driven rain intensity was determined as a function of the angle of rain 

incidence, which was measured from the normal to the plane of incidence and given by the 

cosine law of spherical trigonometry [22]: 

( α θ) 

= cosα 

cosθ 

± sin αsin 

θcos( 

z z ) 

cos m m 

(7) 

where, α is the raindrop inclination from vertical, θ is the slope gradient, and zα and zθ are the 

azimuth from which rain is falling and the azimuth towards which the plane of surface is 

inclined, respectively. In the second term of Eq. (7), the positive sign indicates the windwardfacing 

slope and the negative sign corresponds to the leeward-facing slope, implying the 

raindrop impact deficit with the same values of the slope degree and the raindrop inclination. 

Mainly, Eq. (7) implied that the wind-driven rain intensity varied with the raindrop inclination 

from vertical and slope degree and aspect. 

29 

α 

θ


Splash cup technique, kinetic energy sensor, and analytical solution used to measure 

the kinetic energies of windless and wind-driven rains led to similar results for windless rains; 

unfortunately, the methods provided relatively different results for wind-driven rains. The 

discrepancy among the methods increased as the wind velocity increased (Table 1). The 

performance and accuracy of the techniques used were evaluated by considering the initial 

assumptions. It appeared that splash cup technique underestimated the kinetic energy. The 

reason for these relatively lesser values was the fact that the calibration study to establish a 

relationship between the amount of sand splashed and the rain energy was performed with 

vertically falling raindrops under windless conditions. It was apparent that at a given rainfall 

energy, there was a significant difference between the effectiveness of the vertical raindrops 

and the inclined raindrops in splashing sand out of the cups. 

On the other hand, the analytical solution resulted in overestimation of the energy of 

wind-driven raindrops. This was because of the assumption that the wind velocity had a xcomponent 

of the raindrop velocity at the nozzle height. As anticipated, the raindrop 

horizontal velocities could not be attained because the horizontal wind velocities drifted only 

a few meters in the tunnel. For this reason, the rain energy measured by the kinetic energy 

sensor was found to be more reliable than those by the splash cup technique and the analytical 

solution. Although the calibration of the kinetic energy sensor was carried out with vertically 

falling raindrops, it did not involve in sand splash, which, we believe, differs significantly 

with wind-driven raindrops and directly relied on the amplitude of electrical pulses produced 

by the impact of raindrops on the surface of the sensor. 

The results of the rainsplash detachment rates from soil surfaces were analyzed for 

two cases of raindrop impact parameters, without angle of incidence and with angle of 

incidence. Fluxes of kinetic energy and momentum were used as rainfall parameters without 

angle of incidence: 

⎛ 1 2 ⎞ 

E r = Ξa 

⎜ mVR 

⎟ 

(8) 

⎝ 2 ⎠ 

r 

a 

( mV ) 

ϕ = Ξ 

(9) 

where, Ξa is the actual number of raindrops and calculated by ( ∀) 

R 

I a in # m -2 s -1 , Er is 

kinetic energy flux in Wm -2 , and ϕr is momentum flux in Nm -2 . If rainsplash detachment was 

assumed to be related to the normal component of raindrop impact velocity [ V cos( 

α mθ 

) ] 

[12,13,15,24], fluxes of kinetic energy and momentum, and raindrop impact pressure can, 

respectively, be calculated by: 

E 

rn 

rn 

⎛ 1 2 ⎞ 2 

= Ξa 

⎜ mVR 

⎟cos 

( α m θ) 

(10) 

⎝ 2 ⎠ 

( mV ) cos( 

α m θ) 

ϕ = 

(11) 

Ξa R 

2 2 ( ρ V ) cos ( α m θ) 

Γ = Ξ 

(12) 

a 

w 

R 

where, Ern (Wm -2 ) and ϕrn (Nm -2 ) are the kinetic energy flux and momentum flux, which are 

related to the normal component of resultant velocity, respectively, Γ (MPa) is the total 

2 2 2 

raindrop impact pressure, and V = V + V with = ∂z 

∂t 

and = ∂x 

∂t 

. 

R 

z 

x 

30 

V z 

V x 

R


u 

(m s -1 ) 

d50 

(mm) 

KE 

(J) 

31 

VR 

(m s -1 ) 

Splash Cup Technique 

0 1.00 1.31E-06 ♣ (3.89E-07) ♦ 2.22 (0.28) 

6 1.63 1.04E-05 (3.26E-06) 3.00 (0.47) 

10 1.53 2.45E-05 (4.06E-06) 5.09 (0.43) 

14 1.54 4.02E-05 (9.02E-06) 6.38 (0.69) 

Kinetic Energy Sensor 

0 1.00 5.11E-06 (1.25E-06) 4.38 (0.58) 

6 1.63 2.47E-05 (5.99E-06) 4.64 (0.56) 

10 1.53 5.51E-05 (8.50E-06) 7.64 (0.60) 

14 1.54 1.07E-04 (1.15E-05) 10.48 (0.57) 

Analytical Solution 

0 1.00 1.73E-05 4.10 

6 1.63 6.05E-05 7.31 

10 1.53 1.03E-04 10.47 

14 1.54 1.95E-04 14.13 

KE = f (u)* R 2 

KE = 2E-06e 0.2473u 0.9555 

KE = 6E-06e 0.2184u 0.9887 

KE = 2E-05e 0.1712u 0.9902 

VR: resultant raindrop velocity at impact; *this illustrates a functional relationship which exists between the 

impact energy and the horizontal wind velocity obtained by the corresponding method in the form of KE = ae bu 

with a and b showing the model parameters; ♣ the E notation means "times 10 to the power"; ♦ standard deviation 

is given inside the parentheses for the kinetic energy and the resultant impact velocity. 

Table 1. The kinetic energies (J) and the resultant impact velocities (m s -1 ) of windless and winddriven 

rains measured by both splash cup technique and kinetic energy sensor and estimated by the 

analytical solution. 

Statistical analyses between rainsplash detachment rate and the rainfall parameters showed 

that Er and ϕr had low correlation coefficients with the detachment rate. This occurred 

because they were unable to account for the changes in raindrop trajectory. Even Ia alone led 

to a much greater correlation coefficient in each case. Very significantly, the introduction of 

angle of rain incidence into parameters produced improvements in the coefficients, and each 

of the parameters, Ern, ϕrn, and Γ, could account for more than 82% of the variation in the 

detachment rates. This suggested that the angle of rain incidence accounted for the differences 

in raindrop fall trajectory in connection with the rain inclination and slope gradient and 

aspect. 

On the other hand, the results of sand detachment by wind-driven rain showed that the 

tangential stress controlled the process rather than compressive stress or the normal 

component of resultant velocity. Kinetic energy flux (Erax) calculated using the horizontal 

component of wind-driven raindrops, [VRsinα], had a greater correlation coefficient than the 

kinetic energy flux (Eray) calculated using the normal velocity component, [VRcosα], with the 

sand detachment rates from the cups. Correlation coefficients with D were 0.96 and 0.54, 

respectively for Erax and Eray at the significance level of P = 0.0001 (Table 2). The reason for 

this might be that the vertical compressive stress of a wind-driven raindrop at impact weakens 

as the raindrop deviates from the vertical and the tangential shear stress becomes stronger. 

Our experimental study demonstrated that tangential jetting of raindrops mainly caused the 

sand detachment from the splash cups by the wind-driven raindrops. Openly, the soil material 

behaved differently from the sand surface, and as wind velocity and angle of rain incidence 

increased, the rate of sand detachment increased even though the rate of soil detachment 

decreased. These findings also indicated that the strength of the surface, such as interparticle 

friction and cohesion, significantly affected the detachment rate and determined the


differential contribution of the compressive and tangential stress to the process under winddriven 

raindrops. 

Eray 

Erax 

D 

Eray 

1.00 

(0.0000) † 

2 

* E = E ( cos α) 

; ** ( ) α sin E E 

2 

ray 

ra 

32 

Erax 

0.53 

(0.0001) 

1.00 

(0.0000) 

rax = ra ; † Numbers in parantheses are significance levels. 

D 

0.54 

(0.0001) 

0.96 

(0.0001) 

1.00 

(0.0000) 

Table 2. Pearson correlation coefficients between the sand detachment rate, D, (g m -2 s -1 ) and the the 

kinetic energy flux related to both normal component, Eray * , (J m -2 s -1 ) and horizontal component, 

Erax ** , (J m -2 s -1 ) of the raindrop impact velocity. 

On the other hand, measured rainsplash transport rates varied in close relationship to the 

raindrop impact parameter (Θ) and wind shear velocity. Therefore, the process was 

successfully modeled under the approach that once lifted off by the raindrop impact, the soil 

particles entrained into the splash droplets traveled some distance, which varied directly with 

the wind shear velocity. The raindrop impacts induced the process that would otherwise be 

incapable of transporting. At last, the wind-driven rainsplash process was related to the 

rainfall parameter and the wind shear velocity and analyzed using a log-linear regression 

technique: 

Q Θ 

s 

a1 

b1 

= k u 

(13) 

1 

* 

where, k1 is the relative soil transport parameter for the wind-driven rainsplash process, u* is 

the wind shear velocity (ms -1 ), and a1 and b1 are the regression coefficients. Eq. (13) 

incorporated the dynamic effects of physical raindrop impact and wind action on the process, 

therefore, provided a basis for modeling interrill rainsplash transport under wind-driven rains. 

Additionally, the results of the study to determine the effects of slope aspect, slope gradient, 

and wind shear velocity on the trajectories of the raindrop-induced and wind-driven soil 

particles indicated that neither slope aspect nor slope gradient significantly predicted the 

splash-saltation trajectory. As a result, we conducted a statistical analysis to fit the average 

trajectories of the process into nonlinear regression model of: 

_ 

2 ( u g) 

X = C 

(14) 

1 

* 

where _ 

X is in m, u* is in ms -1 , and g is in ms -2 . C1 is a model parameter. These results also 

contradicted the previous approach of the splash-saltation transport based on only the slope 

aspect and gradient for defining the process. 

Along with the substantial effects of the wind on raindrop impact parameter and 

rainsplash detachment and transport processes, there were significant wind effects on 

sediment transport by raindrop-impacted shallow flow. This process was modeled based on 

interrill erosion mechanics [13,14,17,18,26]:


a b c 

q s = kE rn q So 

(15) 

where, k is soil transport parameter for the sediment transport by raindrop-impacted shallow 

flow and , a, b, and c are regression coefficients to which kinetic energy flux (Ern), unit 

discharge (q) and slope (So) are raised, respectively. Flux of rain energy computed by 

combining the effects of wind on the velocity, frequency, and angle of raindrop impact and 

unit discharge and slope adequately described the characteristics of wind-driven rains and 

significantly explained the variations in sediment delivery rates to the shallow flow transport 

(R 2 ≥ 0.91). Analyses of the Pearson correlation coefficients additionally showed that a 

significant difference occurred in shallow flow hydraulics with different aspects under the 

impacts of wind-driven raindrops. The reverse / advance particle splashes and the lateral 

stress of impacting raindrops at angle with respect to the shallow flow direction were 

concluded to have significant effects on the shallow flow hydraulics under wind-driven rains. 

Further analyses to understand the effects of roughness elements on the sediment transport 

capacity of raindrop-impacted shallow flow were conducted by partitioning the resultant 

kinetic energy into its vertical and horizontal components since the magnitude of those 

significantly changed with wind velocity, slope aspect and gradient and accordingly their 

effects on thin flow hydraulics. 

KE 

KE 

x 

y 

2 

= KEsin 

( α ± β) 

(16) 

2 

= KE cos ( α ± β) 

(17) 

Ω = γqS 

(18) 

s 

0 

a b 

= kKE xKE 

y 

c 

(19) 

q Ω 

where, Ω is the stream power as a flow parameter (kg s -3 ). 

CONCLUSIONS 

This paper aims to give a review of wind-driven rain erosion research performed in I.C.E 

wind tunnel rainfall simulation facility giving the principal discrepancies obtained in water 

erosion sub-processes when wind came into play during rains. Concepts and mechanisms 

were discussed giving experimental results on the effects of wind on the drop size 

distribution, rain intensity and energy, rainsplash detachment and transport, and thin flow 

transport capacity. 

REFERENCES 

[1] Cornelis, W., Erpul, G., D. Gabriels. The I.C.E. Wind Tunnel for Wind and Water Interaction Research. 

Wind and Rain Interaction in Erosion, Visser, S. and Cornelis, W. (Eds.), Tropical Resource Management 

Papers, Chapter 13, p (195 - 224). Wageningen University and Research Centre (2004). 

[2] Ellison, W. D. Soil erosion studies (7 parts). Agr. Eng. 28: 145-146; 197-201; 245-248; 297-300; 349-351; 

407-408; 447-450 (1947). 

[3] Erpul, G., D. Gabriels, D. Janssens. “Assessing the Drop Size Distribution of Simulated Rainfall in a Wind 

Tunnel,” Soil & Tillage Research, 45, 455-463 (1998). 

[4] Erpul, G., D. Gabriels, D. Janssens. “Effect of Wind on Size and Energy of Small Simulated Raindrops: A 

Wind Tunnel Study,” Int. Agrophysics, 14, 1-7 (2000). 

33


[5] Erpul, G., D. Gabriels, L. D. Norton,. “Wind effects on sediment transport by raindrop-impacted shallow 

flow”, Earth Surface Processes and Landforms, 29: 955-967 (2004). 

[6] Erpul, G., D. Gabriels, L. D. Norton. “Sand Detachment by Wind-driven Raindrops”. Earth Surface 

Processes and Landforms, 30: 241-250 (2005). 

[7] Erpul, G., L. D. Norton, D. Gabriels. “Raindrop-Induced and Wind-Driven Particle Transport,” Catena, 47, 

227-243 (2002). 

[8] Erpul, G., L. D. Norton, D. Gabriels. “Sediment Transport From Interrill Areas under Wind-Driven Rain”, 

Journal of Hydrology, 276 (1-4), 184-197 (2003). 

[9] Erpul, G., L. D. Norton, D. Gabriels. “Splash – saltation trajectories of soil particles under wind-driven rain”, 

Geomorphology. 59: 31-42 (2004). 

[10] Erpul, G., L. D. Norton, D. Gabriels. “The Effect of Wind on Raindrop Impact and Rainsplash 

Detachment”, Transactions of American Society of Agricultural Engineering. Vol. 45(6): 51-62 (2003). 

[11] Gabriels, D., Cornelis, W., Pollet, I., Van Coillie, T., Quessar, M. The I. C. E. wind tunnel for wind and 

water erosion studies. Soil Technology. 10: 1-8 (1997). 

[12] Gilley, J. E. & Finkner, S. C. Estimating soil detachment caused by raindrop impact. Transactions of the 

American Society of Agricultural Engineering, 28, 140-146 (1985). 

[13] Gilley, J. E., Woolhiser, D. A. & McWhorter, D. B. Interrill soil erosion. Part I: Development of model 

equations. Transactions of the American Society of Agricultural Engineering, 28, 147-153 and 159 (1985). 

[14] Guy, B. T., W. T. Dickinson and R. P. Rudra. The roles of rainfall and runoff in the sediment transport 

capacity of interrill flow. Transactions of the ASAE 30(5): 1378-1386 (1987). 

[15] Heymann, F. J. A survey of clues to the relation between erosion rate and impact parameters. In: 

Proceedings of International Conference on Rain Erosion and Allied Phenomena. Second Rain Erosion 

Conference, The Royal Aircraft Establishment, Farnborough, England, 2, pp. 683-760 (1967). 

[16] Hudson, N. W. The influence of rainfall mechanics on soil erosion. M. Sc. Thesis, University of Cape Town 

(1965). 

[17] Julien, P. Y. and D. B. Simons. Sediment transport capacity of overland flow. Transactions of the ASAE 28: 

755-762 (1985). 

[18] Parsons, A. J., S. G. L. Stromberg and M. Greener. Sediment-transport competence of rain-impacted 

interrill overland flow. Earth Surf. Processes and Landforms, 23: 365-375 (1998). 

[19] Poesen, J. An improved splash transport model. Z. Geomorph. N. F., 29: 193-221. 69-74 (1985). 

[20] Samray, H., Erpul, G., Gabriels D. The effect of slope aspect on sediment transport by shallow overland 

flow under wind-driven rain. 18th International Soil Meeting (ISM) on “Soil Sustaining Life on Earth, Managing 

Soil and Technology”, May 22 – 26, 2006 Şanlıurfa – Turkey, Proceedings, Volume 1: 459 – 464 (2006). 

[21] Savat, J. and J. Poesen. Detachment and transportation of loose sediments by raindrop splash. Part I: The 

calculation of absolute data on detachability and transportability. Catena 8: 1-18 (1981). 

[22] Sellers, W. D. Physical Climatology. University of Chicago Press, Chicago, Ill. pp. 33-35 (1965). 

[23] Sensit. Model V04 Kinetic Energy of Rain Sensor. Portland, N. D.: Sensit Company (2000). 

[24] Springer, G. S. Erosion by liquid impact. John Wiley and Sons, Inc., New York (1976). 

[25] Van Heerden, W. M. An analysis of soil transportation by raindrop splash. Trans. ASAE, 10:166-169 

(1967). 

[26] Zhang, X. C., M. A. Nearing, W. P. Miller, L. D. Norton and L. T. West. Modeling interrill sediment 

delivery. Soil Sci. Soc. Am. J. 62: 438-444 (1998). 

34


35

Workshop IC-PLR 2006 – Theme A – Soil and groundwater pollution and remediation 

WORKSHOP THEME A – SOIL AND GROUNDWATER 

POLLUTION AND REMEDIATION 

Sub-theme : Managing contaminated soils using phytoremediation 

Erik Meers, Filip M.G. Tack, Marc G. Verloo 

Paper/poster : Comparison of amendments used to remediate acid mine 

tailings: Environmental and Agricultural Applications - Kelly A. Senkiw, 

Tee Boon Goh 

Paper/poster : Study on the effects of trade village waste on accumulation 

of Cu, Pb, Zn and Cd in agricultural soils of Phung Xa Village, Thach 

Thanh District, Ha Tay Province - Nguyen Huu Thanh, Tran Thi Le Ha, 

Nguyen Duc Hung, Tran Duc Hai 

Paper/poster : Metal contamination in irrigated agricultural land : case 

study of Nairobi River basin, Kenya – P.N. Kamande, F.M.G. Tack 

Sub-theme : Managing groundwater pollution from waste disposal sites 

Kristine Walraevens, Marleen Coetsiers, Kristine Martens, Marc Van Camp 

Paper/poster : Contamination of the Marimba River Tributary, Zimbabwe, 

with Cu, Pb, Zn and P by industrial effluent and sewer line discharge – 

Bangira C., Wuta, M. Dube, H.M., Chipatso, L. 

Paper/poster : Controlling phosphorus (P) mobility in poorly P sorbing 

soils : drinking-water treatment residuals (WTR) to the rescue – S. Agyin- 

Birikorang, G.A. O'Connor, L.W. Jacobs 

Paper/poster : Heavy metal contamination of soil and surface water by leachates 

of an open dump of municipal solid waste : a case study of oblogo landfill in the 

Ga West District of Accra, Ghana – Abuaku Ebenezer 

Conclusions 

36


Abstract 

Sub-theme : MANAGING CONTAMINATED SOILS USING 

PHYTOREMEDIATION 

Erik Meers, Filip M. G. Tack, Marc G. Verloo 

Laboratory of Analytical Chemistry and Applied Ecochemistry, Ghent University, Ghent, Belgium 

Soil contamination with heavy metals is a widespread environmental issue, remediation of which is hampered by 

excessive economic costs. Phytoremediation is the use of plant based techniques for soil remediation. This 

technology can help to solve some of the environmental issues involved, yet only under certain conditions. Some 

of the do’s and don’t of phytoremediation applications will be discussed during the oral presentation. 

SOIL CONTAMINATION 

An unfortunate byproduct of industrialization has been the contamination of soil and water 

resources with heavy metals, metalloids and other harmful substances. Over the last decades, 

awareness of the problem has grown considerably, as has the insight that the problem is more 

widespread than was initially assumed [1]. Conventional soil remediation techniques fall short 

of expectation to tackle the overwhelming task at hand due to their high cost: engineering 

techniques cost between €40 - €400 per m3 of soil treated [2]. In Flanders (Belgium, Europe) 

average soil remediation costs are estimated at €310 per ton (based on [3]). The estimated 

total cost for remediation of historically polluted soils is estimated at 7 billion euro [4]. In 

Europe, overall cleanup costs for historic pollution are estimated to run into the 100 billion 

euro range [5, 1]. Budget estimates for soil remediation generally exclude the necessity to 

remediate light to moderately contaminated sites due to low priority and already high cost 

involved in cleaning the heavily polluted sites. 

PHYTOREMEDIATION 

Phytoremediation has been proposed as an economic alternative for some of the 

environmental issues involved in heavy metal pollution [6, 7]. Phytoextraction is a plant based 

technique aimed at removing inorganic contaminants from the soil matrix by plant absorption 

and translocation to harvestable plant parts. By subsequently removing the metal-enriched 

biomass from the site, a gradual attenuation of the contamination in the top soil layer is 

achieved. 

As a soil remediation technique, it offers the following advantages over conventional 

remediation techniques: as an in situ technique, it is less invasive and more economic than 

civil-engineering earth moving techniques. Also, it can be applied over extended surface areas 

and targets the “bioavailable” soil fraction of heavy metals, which is the most relevant 

fraction from an environmental risk assessment perspective. The most important drawback is 

the long required remediation period (years to decades). The sense of uncertainty in regards to 

system consistency and performance predictability of biological remediation systems can also 

be perceived as a drawback. The use of soil amendments to increase accumulation of heavy 

metals in harvestable plant parts can also increase the risk of leaching. In addition, elevated 

37


aboveground plant concentrations also run the risk of entering the foodchain through 

herbivory of the phytoextraction crops. 

RESEARCH FINDINGS 

Phytoextraction research at our laboratory [8] revealed several important findings: 

Firstly, phytoextraction as a soil remediation technique can only be applied on lightly 

to moderately contaminated soils. This not only for plant tolerance reasons, but also because 

reducing metal concentrations in more heavily polluted soils to levels below legal soil 

sanitation criteria would take excessively long periods of time (in the order of centuries). 

Secondly, phytoextraction is not equally applicable for all heavy metals as plants have 

a different affinity for uptake of the various metals. Particularly for Cd and Zn the technique 

appears to be suitable, and to a lesser extent also for Cu. 

Thirdly, since the technique is slow working (order of years and decades) it is 

considered a vital prerequisite to economically re-valorize the produced biomass for industrial 

applications. A viable approach is to employ bio-energy crops with affinity for metal removal. 

These energy crops can be converted into electrical and thermal energy. However, the fate of 

the accumulated metals in the phytoremediation biomass needs to be monitored closely during 

the conversion processes. Other industrial applications can be found in the paper industry, 

fibre industry, wood industry and so on. 

During the presentation, several field studies will be presented in which phytoextraction of 

heavy metals is examined. 

REFERENCES 

[1] C. Ferguson, H. Kasamas. “Risk assessment for contaminated sites in Europe”. CARACAS publication. 

LQM Press, Nottingham (UK), 223 p. (1999) 

[2] S.D. Cunningham, D.W. Ow. “Promises and prospects of phytoremediation”. Plant Physiology, 110, 715- 

719. (1996) 

[3] F. De Naeyer. “Soil Remediation Projects: the new guidelines and daily practice”. Studyday TI-KVIV (30/3), 

Technological Institute. (Translated from dutch). (2000) 

[4] Ecolas. “Financial cost estimation in regards with soil sanitation”. OVAM (Public Waste Agency of 

Flanders), Mechelen, Belgium. (Translated from Dutch). (2001) 

[5] D.J. Glass. “U.S. and international markets for phytoremediation”, 1999-2000. D. Glass Associates Inc., 

Needham (USA), 266 p. (1999) 

[6] A.J.M. Baker, R.R. Brooks. “Terrestrial higher plants which hyperaccumulate metallic elements – a review 

of their distribution, ecology and phytochemistry”. Biorecovery, 1, 81-126. (1989) 

[7] A.J.M. Baker, S.P. McGrath, R.D. Reeves, J.A.C. Smith. “A review of the biological resource for possible 

exploitation in the phytoremediation of metal-polluted soils”. In: Terry, N. & Bañuelos, G.S. (Eds.), 

Phytoremediation of Contaminated Soil and Water. CRC Press LLC, Boca Raton, FL, 85-107. (1999) 

[8] E. Meers. “Phytoextraction of heavy metals from contaminated dredged sediments”. ISBN 90-5989-053-1, 

341 pp., Ghent University, Ghent, Belgium. (2005) 

38


COMPARISON OF AMENDMENTS USED TO REMEDIATE ACID 

MINE TAILINGS: ENVIRONMENTAL AND AGRICULTURAL 

APPLICATIONS 

Abstract 

Kelly A. Senkiw and Tee Boon Goh * 

Department of Soil Science, University of Manitoba, Winnipeg, Canada R3T 2N2 

In environments with low pH, a large portion of the total copper can exist in the labile and potentially toxic 

water-soluble form, while the rest is distributed among chemical forms that are less bioavailable. Copper was 

sequentially extracted from acid mine tailings, in order to assess the potential lability and availability of the 

metal. Four amendments were applied to the tailings in an incubation study, and sequential extraction was used 

to examine the distribution of copper among six fractions. The control was highly contaminated with copper, 

containing 564 mg kg -1 of water-soluble copper. The addition of wheat straw (WS) reduced this form to 305 mg 

kg -1 . The addition of an alkaline extract of humic substances from leonardite (HS) decreased the free copper to 

72 mg kg -1 , while the combination of HS+WS reduced it to 30 mg kg -1 . The CaCO3 amendment reduced free 

copper to near zero. The amendments increased the pH of the tailings in the order of Lime > HS+WS > HS > 

WS. Total copper in the tailings ranged from 1816-2275 mg kg -1 by summation of copper in the six fractions. 

Total copper by acid digestion was 2257-2360 mg kg -1 . The efficiency of the sequential extraction method 

varied from 75 to 96%. Lime was the most effective at reducing the potential availability of copper, followed by 

HS+WS, then HS. 

INTRODUCTION 

Many regions in Canada have been mined for natural resources such as coal and industrial 

metals. The aboveground storage of mine tailings exposes previously buried minerals to the 

surface environment. Here, accelerated chemical and biological weathering can occur, with 

the associated risk of contamination by heavy metals (Barnhisel et al. 1982, Amacher et al. 

1995). The presence of sulphur-containing minerals at mine sites is a precursor to the 

production of sulphuric acid by the process of oxidation, resulting in a pH as low as 3.5 

(Dixon et al. 1982). Heavy metals such as Cu, Ni, Zn, Mn and Fe are often present in mine 

spoils, and their mobility and toxicity may be increased in acidic environments (Barnhisel et 

al. 1982). The potentially toxic combination of a low pH and dissolution of heavy metals are 

hazardous to vegetation and habitats bordering mine tailings. Hence the reclamation of mine 

spoils or tailings must involve a neutralization of pH, as well as a reduction of lability, 

availability and toxicity of free metal ionic contaminants. 

Several mines operated within Manitoba in the early twentieth century, in the region 

that is now Nopiming Provincial Park. Today, the tailings of a former gold mine cover an area 

of approximately 5400 m 2 and have remained virtually barren since the mine’s closure, in 

1937, despite several recent attempts at revegetation on site. It is believed that revegetation 

has been limited by the acidity and extremely high concentrations of copper and other metals 

in the tailings (Renault et al. 2000). The acid portion of the tailings have a pH of 3 to 5, and 

contain, on average, 2300 mg kg -1 total copper (by digestion) (Ibrahim and Goh 2004). 

Merely knowing the total contents of heavy metals (such as copper) in a soil provides 

limited information about the potential behaviour and bioavailability of the metals. Soil 

texture, pH, organic matter content, and Fe/Mn oxides also influence the lability and 

bioavailability of copper. A heavy metal in soil can be associated with many of these soil 

components. Sequential extraction techniques have been employed to examine the 

39


distribution of metals, such as copper, among soil micronutrient pools (Shuman 1985; Sims 

1986; Alva et al. 2000; Kabala and Singh 2001). Shuman (1991) describes six conceptual 

micronutrient pools in soils: water-soluble; exchangeable; precipitated as carbonate; 

associated with Fe, Mn, and Al-oxides; organically-bound; and residual (hereafter referred to 

as fractions F1 to F6). The water-soluble and exchangeable forms of metals are considered 

readily labile and available to plants, while the other forms can be considered relatively 

inactive or strongly bound (Alva et al. 2000). 

Copper is a trace element that is essential to the nutrition of plants and animals. The 

average Cu content in soils is around 30 ppm with a range from 2-100 ppm (Aubert and Pinta 

1977) and it is well-documented that excessive bioavailability of copper is toxic. In fact, the 

soil-plant continuum functions as a natural barrier against toxicity to animals. Plant growth 

(e.g. revegetation of copper-contaminated tailings) will either be greatly reduced or will cease 

before a dangerously toxic amount would be accumulated and transferred to animals via the 

food chain. 

Organic matter accounts for many useful functions in soils, sediments and natural 

waters (Aiken 1985). Studies using humic substances obtained from lignite as a soil 

conditioner or amendment are rare. Whiteley and Williams (1993) investigated a metalcontaminated 

mine spoil (pH = 5.1) after amendment with three forms of lignite: untreated 

lignite; and the insoluble and soluble extracts obtained after an oxidation treatment. The 

authors concluded that the lignite treatment may be a valuable reclamation tool, as it 

improved the survival of non-tolerant cultivars in a Cd-, Pb-, Zn-contaminated mine spoil. 

However, the composition of the lignite was not known with certainty. Preliminary 

investigations in our laboratory revealed that humic substances constitute most of the organic 

matter in leonardite, a coal mine overburden material that is rich in carbon, but is usually 

discarded because it does not burn like coal. It was of interest to investigate if the humic 

substances that can be obtained following alkaline chemical extraction of leonardite was of 

benefit in the reclamation of copper-contaminated mine spoils. 

The objectives of this study were to assess the copper distribution among six defined 

fractions, and thereby approximate the lability and the bioavailability of copper, within the 

mine tailings; and, further, to investigate the potential of alkaline humic substances from 

leonardite, lime, and wheat straw amendments to reduce the lability and bioavailability of 

copper after incubation for 24 weeks. 


Acid mine tailings were collected from the surface of the Central Manitoba Mine site. The 

tailings were then stored at room temperature in a covered, five-gallon plastic pail. 

The mine tailings have a sandy loam texture, with 48.5% sand, 47.2% silt, and 4.3% 

clay. Their organic matter content is very low (2.1 g kg -1 ), and total copper contents are 

extremely high (≥2000 mg kg -1 ) (Renault et al. 2000; Ibrahim and Goh 2004). 

The experiment was designed to compare the effects of different organic amendments 

on the distribution of copper in the mine tailings. Humic substances (HS), fresh wheat straw 

(WS), and lime (CaCO3) were mixed with the mine tailings in four combinations. All 

experimental units were 200 g of mine tailings. For the HS treatment, 14 mL of liquid HS, 

(5.62% Organic Carbon), pH = 10.5, was added. The WS, containing 65.5% carbon, was 

ground by hand and 2.29 g was added to the tailings. The amounts of HS and WS applied 

corresponded to 4.0 and 7.5 g C kg -1 tailings, respectively. The third treatment was the 

combined addition of HS+WS, at the same rates. The lime was applied at a rate of 4 g CaCO3 

40


kg -1 tailings. Nitrogen (N) was added to all samples except the Control at the rate of 50 mg N 

kg -1 tailings. All samples were prepared in triplicate and placed in 500 mL plastic containers 

with lids. The samples were incubated at 20°C for 24 weeks and their moisture was 

maintained at 60% of the water holding capacity throughout the incubation period. 

Fractionation of Copper 

Total copper concentration of the tailings was determined following digestion of a sample 

with aqua regia. In addition, six fractions of copper (labeled F1 to F6) were extracted 

according to the procedure of Salbu et al. (1998). After each step, the supernatant was 

separated by high-speed centrifugation for 30 min at 10,000 x g. The residue was washed 

with 10 mL of deionized water and the wash was combined with the supernatant. All 

supernatants were refrigerated until analysis for copper content by graphite furnace atomic 

absorption spectrophotometry. The sequential extraction was conducted in the following 

manner: 

A two-gram subsample of tailings and 20 mL of deionized water were combined in a 

50 mL polycarbonate centrifuge tube and shaken for 1 hour at 20°C. The supernatant 

containing the water-soluble copper, denoted Fraction 1 (F1), was collected and stored. 

The F1 residue (i.e. the soil following F1 extraction) was extracted for 2 hours with 20 mL of 

1 mol L -1 ammonium acetate, pH 7 to obtain the exchangeable copper (F2) from the mine 

tailings. To obtain Fraction 3 (F3), the F2 residue was extracted for 2 hours on a shaker with 

20 mL of 1 mol L -1 ammonium acetate, pH 5. Fraction 4 (F4), the metal-associated (or 

specifically-sorbed) copper, was collected by combining the F3 residue with 20 mL of 0.04 

mol L -1 NH2OH-HCl solution for 6 h in a 60°C water bath. To collect Fraction 5 (F5), the 

organically complexed copper, the F4 residue was extracted for 5.5 h in an 80°C water bath 

with 15 mL of 30% H2O2, pH 2. After cooling, 5 mL of 3.2 mol L -1 ammonium acetate was 

added and the sample was shaken for 30 minutes. The solution was brought up to 20 mL with 

deionized water. Finally, all of the remaining copper in the sample was extracted into 

Fraction 6 (F6). The residue from F5 was allowed to dry for a few minutes. One gram of the 

residue was placed into an Erlenmeyer flask and digested with 10 mL of 7 mol L -1 HNO3 on a 

hotplate for 6 hours. After dissolution with 1 mL of 2 mol L -1 HNO3, the contents were made 

up to 10 mL. 

Analysis for Copper Concentration 

The copper concentration of all extracts was determined by graphite furnace atomic 

absorption spectrophotometry (AAS). Standard copper solutions were prepared in each of the 

matrices utilized in the sequential extraction procedure. 

Data Analysis 

The experiment was carried out as completely randomized design (CRD). The copper 

fractions (F1-F6), and total copper (by sum of fractions, and by digestion), were randomized 

among the treatments (Control, HS, HS+WS, WS, and Lime). Analysis of variance 

(ANOVA) was performed using Statistical Analysis Software (SAS Institute 2000). 

41


Effect of Amendments on pH of the Tailings 


The pH measurements (1:1; soil:water) of the tailings after the incubation period of 24 weeks 

are listed in Table 1. The pH of the control tailings was 3.32. As expected, lime was the most 

effective treatment, raising the pH to 5.59. The HS alone augmented the tailings’ pH to 4.5, 

whereas the WS alone increased the pH by a slight 0.6 units compared to the control. In 

comparison, the combined HS+WS treatment raised the pH to 5.02. The combination of 

HS+WS caused a 50-fold reduction in the acidity (i.e. 1.7 pH units), compared to the control. 

Despite the fact that all four treatments were able to increase the pH of the mine 

tailings above the initial value of 3.32, the pH still remained in the acidic range. This means 

that following the application of the amendments containing HS at the rate used in this 

experiment, site rehabilitation by revegetation may still not be possible since the availability 

of heavy metals is expected to be high in acidic environments. Some plants may be able to 

tolerate the slightly acidic pH in the lime- and HS+WS- amended tailings, but further 

investigation will be necessary to identify these plant species. 

Effects of Amendments on the Distribution of Copper 

The total copper measured by fractionation in the control tailings was 1816 mg kg -1 (Table 1). 

Of this total, 31% or 564 mg kg -1 of Cu was found in F1, the water-soluble fraction. This is 

an extremely high amount, and is expected to be very toxic to organisms. The organicallycomplexed 

fraction (F5) contains the largest portion of copper in the untreated tailings (34%) 

(Table 1 and Fig. 1). 

The total copper extracted from the tailings treated with alkaline HS was 1824 mg kg -1 

This was very similar to the amount of total copper obtained from the control. The watersoluble 

copper was drastically reduced from 564 to 72 mg kg -1 (Table 1). The copper was 

redistributed into the other fractions, i.e. F2 to F6. The largest increase was observed in F5, 

which rose to 872 mg kg -1 compared to 618 mg kg -1 in the control, although this difference is 

not significant. However, the observed increases in the copper content of the F2 and F3 

fractions were significant compared to the control. Furthermore, if fractions F1 (watersoluble) 

and F2 (exchangeable) are indicative of the most available fractions of Cu, it is 

observed that the HS treatment may greatly reduce the availability of Cu to plants. The size 

of the residual copper pool (F6) in the HS treated tailings was the largest of all amendments, 

at 23%. 

The fractionation procedure extracted almost 2300 mg kg -1 of total copper from the 

tailings treated with HS+WS. The soluble, toxic form of copper was reduced to 1% of the 

total copper extracted, or 30 mg kg -1 (Table 1 and Fig. 1). The organically bound copper 

comprised 52% of the distribution, and was significantly higher than the F5 of all other 

treatments. A total of 11.5 g C was added per kg tailings, which is the highest of all the 

treatments. Because organic matter provides surface sites for adsorption and complexation of 

copper, it is expected that increasing additions of carbon residues will correspondingly raise 

the copper in F5. The HS+WS amendment was very effective at reducing the toxic forms of 

copper, while redistributing the copper to fractions where it is strongly held (F4, F5, F6) and 

thus considered to be less bioavailable. 

When applied alone, the WS did not reduce the free copper as much as the 

amendments containing the alkaline HS. The water-soluble copper was reduced from 30% in 

the control, to 15% in the WS-treated tailings (Fig. 1). However, the 305 mg kg -1 of free 

copper (Table 1) was still extremely high, and poses a toxicity hazard to organisms. It is 

42


possible that the low pH of the WS-amended tailings may have limited microbial activity and 

the ability of WS carbon to play a role in immobilizing copper. In contrast, when WS was 

added in combination with HS, the water-soluble copper was reduced to 30 mg kg -1 . The 

slightly higher pH observed in the tailings that received the HS+WS treatment may have 

contributed to the reduction in F1, compared to the control. The pH of 5.02 was probably 

more favourable for the carbon of the WS to be used by microbes, and thus through 

decomposition, the WS may have contributed some active surface sites to which Cu could be 

adsorbed or chelated. 

A total of 1989 mg kg -1 of copper was extracted from the tailings treated with Lime. 

The water-soluble copper was negligible, at only 7 mg kg -1 . This is a reduction of 80 times 

compared to the control. The copper was redistributed to all other fractions, with greatest 

gains in F4 and F6. The lime treated tailings had the largest increase in F4 of all the 

treatments, at 22% of the total distribution, compared to 11% in the control. This provides 

evidence that the F4 fraction obtained by this fractionation scheme extracts some carbonate 

bound copper, in addition to metal-oxide bound copper. 

In this study, an amendment was considered effective based on several observations. 

Firstly, if it elevated the pH of the tailings, then the lability of copper would be reduced (Sims 

1986; Alva et al. 2000). The water-soluble copper is the most toxic form, followed by the 

adsorbed and exchangeable forms. Thus, if an amendment reduced the copper in these 

fractions, it was considered beneficial in decreasing the potential for mobility and toxicity. A 

corresponding increase of copper in fractions where it is tightly bound or unavailable (i.e. F4, 

F5, and F6), was also considered a benefit. There is some uncertainty as to whether the 

carbonate-bound fraction (F3) is labile and available. This would depend on the pH, since the 

Cu sorbed by carbonates may have a transient existence in carbonate minerals. In an acidic 

environment the Cu may be released upon dissolution of the carbonate. Thus, fraction F3 

represents a potentially mobile and available pool among the total copper. 

The treatments HS, HS+WS, and Lime, all drastically reduced the F1 fraction of 

copper in the tailings (Table 1). The amount of water-soluble copper in the tailings amended 

with Lime plunged to a nearly negligible amount of 7 mg kg -1 . The treatments containing 

modified leonardite (HS and HS+WS) were both highly effective compared to the control, 

with HS+WS outperforming HS alone (30 and 72 mg kg -1 , respectively). 

The amount of free copper in soil solution is very important because this form is 

readily absorbed by plant roots. In soil solutions with pH < 6.0, the dominant species of 

copper is the divalent cation, Cu 2+ (Harter 1991). As the pH increases, two hydrolysis 

reactions occur fairly quickly. 

Cu 2+ + H2O � Cu(OH) + + H + log K = -7.70 [1] 

Cu(OH) + + H2O � Cu(OH)2 + H + log K = -6.08 [2] 

If an amendment was able to increase the pH, the more unavailable chemical forms of copper 

such as Cu(OH) + , Cu(OH)2, and even CuO would be formed. 

The results show that all treatments caused some of the water-soluble copper to be 

redistributed from F1 to F2. However, the copper in F2 is still relatively labile, and still poses 

a toxicity threat because it may be released into solution via cation exchange, or may be 

subject to plant uptake. In a practical sense, it must also be noted that the quantities of copper 

held in the exchangeable fraction are very small when compared to the total copper in the 

tailings. For the Control and WS treatments, where F1 is very large, exchangeable copper 

contributes very little to the potentially toxic copper in the tailings. But, for treatments with 

small amounts of Cu in F1, namely HS, HS+WS, and Lime, F2 values are approximately 

43


equal to the amount of water- soluble copper, and thus they contribute more to potential 

toxicity or bioavailability. 

All treatments significantly increased the amount of copper in the carbonate-associated 

fraction, F3 (Table 1). Despite the statistical differences between treatments, the relative size 

of the F3 fraction only varied from 8.7 to 9.9% in all of the amended tailings (Fig. 1). There 

is some uncertainty concerning the classification of F3 as carbonate-bound Cu (Shuman 

1991). We doubt that in this instance, that F3 represents carbonate bound Cu, since, in the 

acid pH conditions of the mine tailings, free calcium carbonate was non-existent. 

Examination of the organically-complexed fraction, F5, reveals several interesting 

observations. This was the largest pool of copper in all treatments, comprising 34 to 52% of 

the total copper (Fig. 1). The amount of organically-complexed copper ranged from 618 to 

1185 mg kg -1 across all treatments, and the differences were found to be statistically 

significant at p < 0.10 (Table 1). As anticipated, the treatment that added the most organic 

material to the tailings, HS+WS, was the most successful at raising the copper in F5. 

Copper ions in soil solution are often complexed with various inorganic or organic 

ligands. Complexation with organic acids or low molecular weight organic matter may 

solubilize copper and render it available for plant uptake or leaching (van der Watt 1991 et al.; 

Merritt and Erich 2003). On the other hand, complexation followed by precipitation with 

complex humic substances may immobilize the copper (Stevenson 1982). 

Effect of Amendments on Potential Lability and Plant Availability of Copper 

The water-soluble and exchangeable forms of metals in soils are considered to be plantavailable 

(Shuman 1991; Alva et al. 2000). The free copper cation or its complexed species 

may be adsorbed to the negatively charged colloids within the soil. Attraction due to 

electrostatic forces is referred to as non-specific or outer-sphere adsorption. This copper is 

exchangeable using salt solutions because of its relatively weak adsorption onto non-specific 

exchange sites (Shuman, 1991). The F3 fraction, considered to be carbonate-bound, is 

sometimes included in this estimate, as metals in this fraction can become available under 

altered environmental conditions (Kabala and Singh 2001). Alternately, copper may form 

covalent bonds with an OH - ligand on a soil colloid, such as Fe, Mn, or Al oxides. If the 

copper forms two covalent bonds with the exchanger, the copper is strongly retained by the 

soil. This is termed specific adsorption. In this case, the copper is not salt-exchangeable. 

The Lability Factor (LF) was employed as an aid in assessing the plant-availability of 

copper in the mine tailings. It is a relative index to compare metal lability among treatments. 

When F1+F2 are the only fractions considered to be labile at the time of fractionation, the 

control tailings have the highest lability, with an LF of 32% (Table 2). The Lability Factors 

for the HS and HS+WS treatments are 6.3 and 4%, respectively. The Lime treatment was 

more effective at reducing the F1 and F2 fractions of copper, resulting in a low LF of 2.4%. 

If fraction F3 is also considered labile, then 37% of the relative distribution of copper 

in the control tailings is potentially toxic. Regardless, the resulting lability factors, Lability 

Factor 2, present the same pattern as described for Lability Factor 1 (Table 2). Hence, the 

treatments containing the alkaline organic amendment (HS and HS+WS) decreased the 

copper LF to less than half of its original value, and the Lime is slightly more effective than 

the HS+WS. 

Caution must be taken when using a Lability Factor to interpret the potential 

movement or availability of metals in soil. It is useful as a discussion tool, but the mobility of 

copper in individual fractions is only assumed, and not measured. Moreover, the values are in 

percentage of the total Cu and not in actual concentration in the soil. The copper extracted 

44


into each fraction, and its lability, will depend upon the individual soil and the metal 

fractionation procedure employed. 

CONCLUSIONS 

The study confirmed that the tailings from the Central Manitoba Mine site are highly 

contaminated with copper, containing approximately 2300 mg Cu kg -1 . The control tailings 

contained 564 mg kg -1 of water-soluble copper, which is readily labile and toxic. 

Approximately one-third of the total copper in the acid tailings is considered potentially toxic. 

All amendments altered the distribution of copper. The Lime was the most effective at 

increasing pH, and decreasing soluble copper. 

The two treatments containing alkaline, humic substances extracted from leonardite were also 

effective at reducing water-soluble copper. The addition of WS with the HS further reduced 

the water-soluble fraction. The treatment HS+WS also had the highest amount of copper in 

the organically-complexed fraction. 

In conclusion, the alkaline humic substances extract used in this research may be a 

valuable addition to a reclamation strategy for acid, copper-contaminated mine tailings. 

ACKNOWLEDGEMENTS 

This study was supported by a research grant from LUSCAR Ltd. to TBG and the James 

Gordon Fletcher Graduate Fellowship in Agricultural and Food Sciences to KAS. 

REFERENCES 

[1] Aiken, G.R. 1985. Isolation and concentration techniques for aquatic humic substances. Pages 363-385. in 

Aiken, G.R., McKnight, D.M., Wershaw, R.I. and MacCarthy, P. (Eds). Humus Substances in Soil, Sediment 

and Water: Geochemistry, Isolation and Characterization. John Wiley, New York.. 

[2] Alva A.K., Huang, B. and Paramasivam, S. 2000. Soil pH affects copper fractionation and phytotoxicity. 

Soil Sci. Soc. Am. J. 64:955-962. 

[3] Amacher, M.C., Brown, R.W., Sidle, R.C. and Kotuby-Amacher, J. 1995. Effect of mine waste on element 

speciation in headwater streams. In: Allen, H., Huang, C.P., Bailey, G.W. and Bowers, A.R. (Eds.). Metal 

Speciation and Contamination of Soil. Lewis Pub. Boca Raton. 

[4] Aubert, H. and Pinta, M. 1977. Trace Elements in Soils. Elsevier, Amsterdam. 

[5] Barnhisel, R.I., Powell, J.L., Akin, G.W. and Ebelhar, M.W. 1982. Characteristics and reclamation of “acid 

sulfate” mine spoils. Pages 225-232. in J.A. Kittrick et al. (Eds.) Acid Sulfate Seathering. SSSA Spec. Publ. 10. 

SSSA, Madison, WI. 

[6] Dixon, J.B., Hossner, L.R., Senkayi, A.L. and Egashira, K. 1982. Mineralogical properties of lignite 

overburden as they relate to mine spoil reclamation. Pages 169-191. in J.A. Kittrick et al. (Eds.). Acid Sulfate 

Weathering. SSSA Spec. Publ. 10. SSSA, Madison, WI. 

[7] Ibrahim, S.M. and Goh, T.B. 2004. Changes in macroaggregation and associated characteristics in mine 

tailings amended with humic substances. Comm. Soil Sci. Plant Anal. 35:1905-1922. 

[8] Kabala, C. and Singh, B.R. 2001. Fractionation and mobility of copper, lead, and zinc in soil profiles in the 

vicinity of a copper smelter. J. Environ. Qual. 30:485-492. 

[9] Merritt, K.A. and Erich, M.S. 2003. Influence of organic matter decomposition on soluble carbon and its 

copper-binding capacity. J. Environ. Qual. 32:2122-2131. 

[10] Renault, S., Sailerova, E., and Fedikow, M.A.F. 2000. Phytoremediation and phytomining in Manitoba: 

preliminary observations from an orientation survey at the Central Manitoba (Au) Minesite (NTS 52L13); in 

Report of Activities 2000, Manitoba Industry, Trade and Mines, Manitoba Geological Survey, p. 179-188. 

[11] Salbu, B., Krekling T. and Oughton, D.H. 1998. Characterisation of radioactive particles in the environment. 

Analyst. 123:843-849. 

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[12] SAS Institute. 2000. SAS User’s Guide: Statistics. Version 8. SAS Institute Inc., Cary, N.C., U.S.A. 

[13] Shuman, L.M. 1985. Fractionation method for soil microelements. Soil Science. 140:11-22. 

[14] Shuman, L.M. 1991. Chemical forms of micronutrients in soils. Pages 113-144. in J.J. Mortvedt et al. (Eds.) 

Micronutrients in Agriculture. 2 nd ed. SSSA. Madison, WI, U.S.A. 

[15] Sims, J.T. 1986. Soil pH effects on the distribution and plant availability of manganese, copper and zinc. 

Soil Sci. Soc. Am. J. 50:367-373. 

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Amelioration of subsoil acidity by application of a coal-derived calcium fulvate to the soil surface. Nature. 

350:146-148. 

[17] Whiteley, G.M. and Williams, S. 1993. Effects of treatment of metalliferous mine spoil with lignite derived 

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capillaris L. Soil Technol. 6:163-171. 

46


Treatment z 

pH 

Control 3.32 564 ± 151 a 16 ± 2.6 c 90 ± 1.1 d 207 ± 13 d 618 ± 199 c 321 ± 73 

HS 4.5 72 ± 36 c 44 ± 6.8 b 171 ± 15 c 237 ± 21 cd 872 ± 240 bc 428 ± 38 

HS+WS y 

Copper in each fraction (mg kg 

5.02 30 ± 0.8 c 63 ± 8.7 a 217 ± 31 a 334 ± 12 b 1185 ± 30 a 446 ± 11 

WS 3.95 305 ± 6.3 b 45 ± 1.9 b 174 ± 3.9 bc 273 ± 6 cd 863 ± 102 bc 341 ± 62 

Lime 5.59 7 ± 0.9 c 40 ± 3.8 b 197 ± 1.3 ab 430 ± 33 a 909 ± 179 ab 405 ± 68 

-1 ) 

F 1 F 2 

F 3 

F 4 

F 5 F 6 

ANOVA df Pr > F 

Trt 4 < .0001** < .0001** < .0001** < .0001** 0.0701* 0.1300 

a-d Mean values followed by the same letter (within columns) are not significantly different. 

z 

Treatments: Control, HS = Humic Substances, WS = Wheat Straw, Lime = CaCO3. 

y 

For HS+WS, all Cu fractions are means of 2 replications. 

* significant at p < 0.10 

** significant at p < 0.05 

Table 1. pH of tailings and mean copper content in each fraction 

47


Treatment Lability Factor 1 z 

Control 

HS 

HS+WS 

WS 

Lime 

31.92 

6.33 

4.09 

17.50 

2.39 

48 

Lability Factor 2 y 

36.88 

15.72 

13.62 

26.21 

12.31 

z Lability Factor 1 = [(F1 + F2) / (Total Cu by Sum)] x 100 

y 

Lability Factor 2 = [(F1 + F2 + F3) / (Total Cu by Sum)] x 

100 

Copper content 

(% of Total by Σ F1-F6) 

100% 

80% 

60% 

40% 

20% 

0% 

Table 2. Copper Lability Factors for each treatment 

Control HS HS+WS WS Lime 

Treatment 

Figure 1. Relative distribution of copper among fractions after 24 weeks. 

F 6 

F 5 

F 4 

F 3 

F 2 

F 1


STUDY ON THE EFFECTS OF TRADE VILLAGE WASTE ON 

ACCUMULATION OF CU, PB, ZN AND CD IN 

AGRICULTURAL SOILS OF PHUNG XA VILLAGE, THACH 

THANH DISTRICT, HA TAY PROVINCE 

Nguyen Huu Thanh 1 , Tran Thi Le Ha 1 * , Nguyen Duc Hung 1 , Tran Duc Hai 2 

1 Hanoi Agricultural University, Hanoi, Vietnam, 2 Postgraduate student, Hanoi Agricultural University, 

Hanoi, Vietnam 

Abstract 

Waste materials from Vinh Loc trade village affected greatly the accumulation of Cu, Pb, Zn and Cd in 

agricultural soil. Seventeen soil samples were taken for analysis. Soil was polluted locally with Zn and Cd. 

The Zn concentrations in 2 samples exceeded the standard and were in a polluted level. The Cd 

concentration of one sample exceeded the standard by 22% with regarding the soil as polluted. Among 17 

soil samples, the percentage of samples contaminated with different heavy metals was 100% for Cu, 59% 

for Pb, 35% for Cd, and 24% for Zn. 

Over 80% of Pb and Cd in soil was extractable by salt solution or diluted acid. This indicates a great 

potential of the soil to cause Pb and Cd toxicity to environment in this village. Fe and Mn oxides had the 

stronger affinity to heavy metals than did organic matter and carbonates. The exchangeable form of heavy 

metals was in the low proportion in soil. 


Metal recycle trade village (metal ware-mechanical trade village) is one of the typical 

features of rural Vietnam in general and particularly in Ha Tay. These trade villages have 

participated greatly in the multi-component economy in the doi-moi period [3, 4]. 

Like other trade villages, metal ware-mechanical trade villages are typical with 

unprompted development of trade villages without planning, the low technical level with 

simple works and relying mainly on experience, and lack of basic training. 

Small scale and scattered production all over the area constitute numerous small 

waste sources. It is difficult to gather the waste material and to treat it in a central facility. 

Evaluation the effects of metal ware-mechanical trade villages on the accumulation of 

heavy metals in agricultural land is to guarantee the sustainable agriculture. 

2.1. Location and sampling 

2. MATERIALS AND METHODS 

Phung Xa commune is situated in Red River delta (Figure 1) with the area of agricultural 

land is 307.1 ha. Residential area and trade village are intermixed. 

49


W 

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Sampling diagram 

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# household.shp 

road.shp 

# sampling_site.shp 

commune.shp 

aquaculture 

cemetry 

contruction area 

irrigation land 

pasture 

resident area 

rice field 

unused water 

Figure 1. Sampling diagram 

Seventeen soil samples (Table 1) were sampled at the surface horizon with a depth from 

0 to 15 cm and were indicated on the sampling diagram in Figure 1. The nearer to waste 

sources, the more densely samples were taken.. 

Sample 

1 

2 

Location 

Dong 

Man 

Dong 

Sau 

Distance 

to 

sources 

(m) 

Altitude Vegetation 

1500 Medium Rice 9 

500 Medium Rice 10 

3 Ben Hiep 500 High Rice 11 

4 Ben Hiep 300 Low Rice 12 

5 Cua Lo 100 Medium Rice 

6 Ben Hiep 250 Medium Rice 

7 

8 

Dong 

Nuong 

Dong 

Sau 

200 Medium Rice 


Sample 

13 

14 

15 

16 

17 

50 

Location 

Dong 

Khoai 

Dong 

Mo 

Dong 

Lac 

Dong 

Lac 

Dong 

Mo 

Cong 

Dinh 

Cong 


Cong 


Cong 


Table 1. Main information on soil samples 

Distance 

to 

sources 

(m) 

Altitude Vegetation 







50 Medium Coriander 


150 Low 

Rice


One waste water sample and one domestic waste water sample was taken in the trade 

village at a distance of 10 m from waste sources to determine their properties. 

2.2. Analytical procedures 

The following procedures were used for analyses. 

Total Cu, Zn, Pb, and Cd were determined after digestion the samples by HF, 

HNO3, and HClO4 [6]. 

Fractionation of heavy metals was done by sequential extraction with following 

solutions [5]: 1M MgCl2 (pH=7), 1M CH3COONa (pH=5), 0.3M Na2S2O4 , 0.175M 

sodium citrate, 0.025M citric acid, and mixture of 0.02M HNO3, 30%H2O2, 3.2M 

CH3COONH4 in 30%HNO3. 

Concentrations of Cu, Pb, Zn, and Cd in the digested solution or extracted solution 

were determined by an atomic absorption spectrophotometer ANA182. Cu, Zn, Pb, and 

Cd was determination at the wave length of 324.8nm; 307.6nm; 283.3nm; 228.8nm 

respectively. 

3.1. Soil properties 

3. RESULTS AND DISCUSION 

Soil texture ranged from loamy sand to clay (Table 2). The clay percentage of the surface 

horizon was mostly greater than 16%. It related to soil properties, fertility, and heavy 

metal absorption ability of soil. 

Almost all samples had a pH higher than 5.6 (medium and light acid). The pH 

values are in harmony with Eutric Fluvisols of the Red River delta with long duration of 

cultivation, together with tropical environment. Furthermore, trade village activities 

might cause a more or less strong change of pH. 

Soil was quite rich in organic matter. The total organic carbon concentration (OC) 

was in a range between 1.47% and 3.15%. Some samples with low altitude or near 

residential area had OC greater than 2%. 

Cation exchange capacity (CEC) varied from 10.2 to 15.4 cmol+/kg soil and was 

in the average to high level. In the study of the relationship of pH, OC, and clay content 

with CEC, as shown later, a correlation coefficient between CEC and OC was 0.66. The 

high OC and CEC are closely related to the existence of heavy metals in soils. 

51


Sample 

Texture 

(FAO- 

UNESCO) 

pH 

OC 

(%) 

CEC 

(meq/100g 

soil) 

Sample 

52 

Texture 

(FAO- 

UNESCO) 

pH 

OC 

(%) 

CEC 

(meq/100g 

soil) 

1 Sandy clay 6.18 1.77 10.56 9 Loam 5.32 1.47 10.55 

2 Sandy clay 5.78 1.73 11.65 10 Sandy loam 6.08 1.98 10.95 

3 Sandy clay 5.21 1.95 10.98 11 Clay loam 6.96 2.91 14.37 

4 Sandy clay 6.12 2.80 12.78 12 Sandy clay 5.97 3.15 13.20 

5 Sandy clay 6.49 2.03 14.33 13 Sandy loam 4.76 2.52 11.12 

6 Clay loam 5.66 1.99 10.16 14 Clay loam 6.31 3.09 15.38 

7 Sandy clay 5.97 2.58 12.13 15 Clay loam 6.69 2.25 12.61 

8 

Loamy 

d 

6.31 1.73 12.97 16 Clay 4.91 2.73 13.39 

17 Clay 5.41 2.56 13.08 

Table 2. Some physical and chemical characteristics of soils 

3.2. Possible factors in the trade village affecting the heavy metal concentration of 

soil 

3.2.1. Exhausted fumes 

According to the research of Ministry of National Defense in 2002, the hanging dust 

concentration in air ranged from 0.26 to 0.31 mg.m -3 while Vietnam standard TCVN 

5937-1995 is 0.3 mg.m -3 . The Pb was detectable in air. The SO2 concentration ranged 

from 0.01 to 0.61 mg m -3 (Vietnam standard TCVN 5937-1995 is 0.3 mg m -3 ) and the 

NOx concentration was in a range between 0.004 and 2.12 mg m -3 (Vietnam standard 

TCVN 5937-1995 is 0.1 mg m -3 ) [2]. Therefore, the exhausted fumes of Vinh Loc trade 

village were regarded having no affect to the heavy metal accumulation in soil. 

3.2.2. Waste water 

Waste water from rolling and plating steel comes to the drainage system. One waste 

water sample collected at a site 10 m distant from the drainage system was analyzed.


Item Unit Value 

Permissible levels in TCVN 5949-1995 

A B C 

pH 4.2 6 – 9 5.5 - 9 5 – 9 

Suspended solids mg/l 725 50 100 200 

Cu mg/l 0.178 0.2 1 5 

Zn mg/l 7.92 1 2 5 

Pb mg/l 0.65 1 2 2 

Cd mg/l 0.02 0.01 0.02 0.5 

Table 3. Some properties of waste water collected at trade village in Phung Xa 

Note: Waste water having values and concentrations: 

o value in column A can be discharged to domestic waterways, 

o value in column B can only be discharged to waterways used for hydro-traffic, aquaculture, 

and cultivation. 

o ranged from value in column B to value in column C can only be discharged to defined places. 

o value column C can not be discharged to any environment. 

Table 3 showed that the concentrations of Cu, Pb and Cd were lower than or equal to the 

permissible level of waste water used for aquaculture and cultivation. However, other 

items of pH, suspended solids and Zn concentration were higher than the permissible 

level. From the criteria of pH and suspended solids, the waste water was not allowed to 

be discharged without treatment. Discharge of such waste water to environment without 

treatment affects soil quality badly. 

According to the field observations, waste water was discharged one part to 

surrounding ponds, lakes and one part directly to agricultural land near the trade village. 

Because ponds and lake around Vinh Loc trade village are not connected with irrigation 

channels of the commune, the pollution of heavy metals in Vinh village is difficult to take 

place in samples 1, 2, 8-11. Heavy metal pollution can only occur in surrounding samples 

as 3-7, 12, 14-17. 

Table 5 showed that the concentrations of Cu, Zn, Pb and Cd in the above samples 

were considerably higher than those of other samples. This proves that waste materials 

from trade village raises heavy metal concentrations in the soil. The concentrations of Cu, 

Pb, Zn and Pb were highest in sample 17. Because this sample site is in a depression with 

stagnant water coming from the village, heavy metals might have accumulated. Similarly, 

sample 4 had higher concentrations of heavy metals and was at the contaminated level. 

This is due to its low altitude compared to samples 3 and 6. 

3.2.3. Others 

Domestic waste rubbish is collected to a designated place and doesn’t considerably affect 

the accumulation of heavy metals in soil. 

Domestic waste water is discarded directly to drainage channels. The results of 

the domestic waste water analysis are presented in Table 4. Table 4 showed that the 

concentrations of Zn, Cu, Pb and Cd in the domestic waste water did not exceed the 

permissible level of the Vietnam standard. Therefore, the accumulation of Zn, Cu, Pb and 

Cd in agricultural land is not affected by the domestic waste water more than by the 

53


waste water from the trade village. However, suspension solid and the NH4 + -N 

concentration in the waste water were very high and even exceeded the standard C level, 

suggesting that the domestic waste water is not allowed to be discarded to the 

environment. 

Item Unit Value 

Permissible levels in TCVN 5949-1995 

A B C 

pH 6.98 6 - 9 5.5 - 9 5 – 9 

Suspension solid mg/l 409 20 50 100 

Cu mg/l 0.01 0.2 1 5 

Zn mg/l 0.087 1 2 5 

Pb mg/l 0.33 1 2 2 

Cd mg/l 0.008 0.01 0.02 0.5 

NH4 + -N mg/l 15.36 0.1 1 10 

Table 4. Some characteristics of domestic waste water 

Furthermore, the accumulation of heavy metals in soil can be influenced by irrigation 

water, fertilizer, and agricultural chemicals. Irrigation water of Phung Xa is taken from the 

Red River and the Dong Mo River and it can be considered that it does not affect seriously 

the heavy metal accumulation in soil. As mentioned above, the main crop in Phung Xa is 

paddy rice. This crop is planted over 96% of the total area for annual crops. This indicates 

that the difference in the influence of fertilizers and agricultural chemicals between samples 

is not great. 

3.3. Total concentrations of Cu, Pb, Zn and Cd in soil 

Most of soil samples were found to have total concentrations of Cu, Pb, Zn and Cd below 

the permissible level in Vietnam standard TCVN 7209-2002. 

The analytical results of heavy metal in agricultural soils are shown in Table 5. 

Sample Cu Pb Zn Cd Sample Cu Pb Zn Cd 

1 39.68* 10 39.33* 

2 43.61* 60.04* 11 43.38* 51.52* 1.45* 

3 42.14* 12 47.79* 53.21* 

4 47.06* 58.94* 142.49* 1.52* 13 39.05* 50.25* 248.36** 2.44** 

5 41.80* 14 42.83* 54.26* 142.00* 1.49* 

6 41.66* 15 40.47* 50.33* 157.23* 1.62* 

7 41.42* 16 47.08* 57.85* 242.70** 1.52* 

8 46.17* 51.39* 17 43.54* 68.24* 155.64* 1.57* 

9 39.44* 

TCVN 7209-2002 50.00 70.00 200.00 2.00 

Note: *, contaminated; **, polluted. 

Table 5. Total concentrations of some heavy metals in agricultural soils in Phung Xa 

(unit: mg kg -1 ). 

54


To evaluate the pollution level in heavy metals of soil, the total concentrations of heavy 

metals were divided into the following three categories: 

- No contamination: heavy metal concentration below 70% of the Vietnam standard. 

- Contaminated: heavy metal concentration in between 70% and 99% of the 

Vietnam standard. 

- Polluted: heavy metal concentration over the Vietnam standard. 

3.3.1. Cu 

Table 5 showed that the total Cu concentrations ranged from 39.05 to 47.79 mg kg -1 and 

were lower than the permissible level (50.0 mg kg -1 in TCVN 7209-2002). Although the 

total Cu concentrations did not exceed the permissible level, every sample was 

contaminated with Cu (more than 35 mg kg -1 ). Samples 4, 12 and 16, which were taken 

from the village border and the waste water receiver from Vinh village, showed the total 

concentration of Cu nearly reaching the permissible level. Other samples taken far from 

Vinh village were less affected by trade village’s activities and had the lower Cu 

concentration. 

3.3.2. Pb 

The total Pb concentrations in soil were from 39.66 to 68.24 mg kg -1 and were below the 

permissible level (72.0 mg kg -1 in TCVN 7209-2002). However, ten samples (59% of total 

samples) were at the contaminated level. The total Pb concentration of sample 17 was 

noted to be close to the permissible level; this sample was taken from the receiver of 

village’s waste water in a low altitude. Like Cu, the total Pb concentrations of samples 4, 

11, 12, 14- 17, which were taken from the area bordering on Vinh village, were higher than 

those of other samples. 

3.3.3. Zn 

The Zn concentration in soil was mostly affected by the waste from the trade village. The 

total Zn concentrations of samples 13 and 16 exceeded the Zn permissible level in soil 

(200.0 mg kg -1 in TCVN 7209-2002). In addition, samples 4, 14, 15 and 17 were in the 

category of the contaminated level. Production installations and plating pools in Vinh 

Loc trade village, mainly zinc plating, probably lead to the local pollution and 

contamination of Zn in agricultural soil. 

3.3.4. Cd 

The total Cd concentrations varied from 1.16 to 2.44 mg kg -1 , and sample 13’s Cd 

concentration is higher than TCVN 7209-2002. The total Cd concentrations of the 

remaining samples were below the Vietnam standard but still in the high level. Especially 

those of samples 4, 11, 14-17 were at the contaminated level. These samples located at 

the border on Vinh village were directly affected from exhausted fumes, dust, and waste 

water from the village, leading to the high total Cd concentration. 

55


3.3.5. Evaluation the heavy metal pollution in agricultural soil 

The total Cu concentrations of all samples were at the contaminated level (70 to 99% of 

TCVN 7209-2002). The total Pb concentrations of samples near Vinh Loc trade village 

were at the contaminated level. Sample 17 had the total Pb concentration close to the 

Vietnam standard. It is worthwhile to pay attention to that agricultural soil in Phung Xa 

was locally polluted by Zn and Cd. The total Zn concentrations in sample 13 and 16 

exceeded the permissible level and at the polluted level. The total Cd concentration of 

sample 13 exceeded the permissible level by 22% and polluted the soil. Some other 

samples around the waste source were in the category of the contaminated level. 

Sample 13 was influenced by some production installations along the road and was the 

most polluted one. This sample was at the polluted level in the total Zn and Cd concentrations 

and at the contaminated level in the total Cu and Pb concentrations, compared to the Vietnam 

standard. 

3.4. Fractionation of heavy metals in soil 

3.4.1. Cu 

Analytical results of fractionation of Cu are shown in Table 7. The data pointed out that 

Cu existed mainly in the form of bonding to Fe and Mn oxides and the residual form 

which is not extractable with salt solution or diluted acid (Cu in crystal network of 

primary and secondary minerals or other forms). In average, the Cu concentration in the 

form bonding to Fe and Mn oxides was 15.46 mg kg -1 , making up 36.18% of total Cu, 

and the Cu in the residual form was 23.10 mg kg -1 , with occupation of 54.06% of total 

Cu. 

On the other hand, exchangeable Cu, and Cu bonded to carbonates and to organic 

matter were in a low concentration. It was as low as 1.08 mg kg -1 in average for the 

exchangeable form, 1.74 mg kg -1 for the bonding-to-carbonates form, and 1.35 mg kg -1 for 

the bonding-to-organic matter form, making up 2.53%, 4.07%, and 3.16% of total Cu, 

respectively. 

The solubility of Cu decreases in the following order: exchangeable, bonding to 

carbonate, bonding to Fe oxides, bonding to Mn oxides, bonding to organic matter, and 

residual forms. In Phung Xa, the concentrations of exchangeable Cu and Cu bonded to 

carbonates were low. As a result, it is evaluated that Cu is less toxic to crops and 

environment, even when the total Cu concentration is high. 

3.4.2. Pb 

Analytical results of fractionation of Pb are presented in Table 8. It showed that 

approximately 50% of total Pb existed in the form of bonding to Fe and Mn oxides. The 

average concentration of this form was 25.35 mg kg -1 . The Pb concentration was lowest 

in the form of bonding to organic matter (average concentration is 4.49 mg kg -1 , making 

up 8.81% of total Pb) and the residual form (average concentration is 4.77 mg kg -1 or 

56


9.36% of total Pb). The concentrations of exchangeable Pb and Pb bonding to carbonates 

were in an intermediate level with averages of 7.57 and 8.78 mg kg -1 , respectively. 

Total of the extractable Pb (exchangeable, and bonding to carbonates, Fe and Mn 

oxides, and organic matter) was 46.19 mg kg -1 in average (nearly reaching the 

contaminated level of 49 mgkg -1 ) and made up 90.64% of total Pb. Total of the 

extractable Pb concentrations of samples 2, 4, 16 and 17 exceeded 49 mg kg -1 . It means 

that the potential Pb toxicity in agricultural soil is high, because Pb easily changes to the 

available form in soil and affects crops, animals, and human being. 

3.4.3. Zn 

Analytical results of fractionation of Zn are presented in Table 9. Different from Cu, the 

concentration of extractable Zn increased from the exchangeable form to the bonding-toorganic 

matter form. In this sequence, the concentration of Zn bonding to carbonates was 

18.81 mg kg -1 and made up 13.09% of total Zn; exchangeable Zn was 20.10 mg kg -1 or 

13.99% of total Zn; Zn bonding to Fe and Mn oxides was 23.84 mg kg -1 or 16.59% of total 

Zn; and Zn bonding to organic matter was 27.16 mg kg -1 or 18.90% of total Zn. The rest of 

Zn is kept in minerals’ crystal structure. The average concentration of this residual form 

was 53.79 mg kg -1 or 37.43% of total Zn. Although the proportion of the extractable forms 

is not so high, it is necessary to pay a great attention to Zn in Phung Xa due to the high Zn 

concentration in waste sources. When Zn comes into soil, 63% of total Zn will exist in the 

extractable forms which easily transform into the available form and affect creatures and 

environment. 

57

20 

15 

10 

5 

0 


1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 

Figure 2. Fractionation of Cu (mg.kg -1 ) Figure 3. Fractionation of Pb (mg.kg -1 ) 

60 

50 

40 

30 

20 

10 

0 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 

Figure 3. Fractionation of Zn (mg.kg -1 ) Figure 3. Fractionation of Cd (mg.kg -1 ) 

Exchange-able 

3.4.4. Cd 

Bonding to carbonates 

1 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

30 

25 

20 

15 

10 

5 

0 

Bonding to 

Fe & Mn oxides 

58 

Bonding to organic matter 

Cd is a very toxic element in soil and can cause toxicity at low concentrations (TCVN 

7209-2002 is 2 mg kg -1 ). Analytical results of fractionation of Cd are presented in Table 

10. It showed that the distribution tendency of Cd in soil was similar to that of Pb and 

that Cd bonding to Fe and Mn oxides occupied the highest proportion in total Cd. The 

average concentration of Cd bonding to Fe and Mn oxides was 0.41 mg kg -1 or 28.47% of 

total Cd. 

The problem is that extractable Cd occupies the very high proportion in total Cd (1.16 mg 

kg -1 or 80.55% of total Cd). Therefore, the risk for Cd toxicity in the soil is very high, 

because Cd easily changes to the available form from the extractable forms, when 

conditions of soil like pH, moisture, and oxidation-reduction potential change naturally or 

caused by fertilizer application.


4.1. Concusions 

4. CONCLUSIONS AND PROPOSALS 

From the study on the effects of the trade village waste on the pollution of agricultural 

soil by heavy metals in Phung Xa, Thach That, Ha Tay, the following conclusions are 

drawn: 

1. The target soil belonged to Eutric Fluvisols with loamy sand to clay texture, quite high 

organic matter concentration, and medium to high CEC. 

2. Waste materials from Vinh Loc trade village affected greatly the accumulation of Cu, 

Zn, Pb and Cd in agricultural soil. Soil was polluted locally with Zn and Cd (samples 13 

and 16 were polluted with Zn and sample 13 with Cd). Furthermore, the ratio of the 

contaminated to total soil samples was 100% for Cu, 59% for Pb, 35% for Cd, and 24% 

for Zn. 

3. Over 80% of Pb and Cd in soil was extractable by salt solution or diluted acid. It made 

great potentiality for causing toxicity to environment. 

4. Fe and Mn oxides showed the stronger affinity to heavy metals than did organic matter 

and carbonates. Exchangeable heavy metals were of low proportion (less than 16% of 

total heavy metal). 

4.2. Proposals 

1. The Phung Xa People Committee is requested to research into the closed production 

technology, to change machines to modern ones, and to control and treat waste water 

and waste solid. Industrial waste water from industrial sites or production installations 

must be treated according to the Vietnam standard before discharge to common 

drainage canals. 

2. Application of lime or phosphate alkali, together with organic fertilizer, to soil in order 

to transform most of heavy metals into hardly soluble forms. 

3. Establishment of the environment management board in commune. 

4. Raising of the environment protection awareness by propaganda and education on 

environment protection to people. 

6. REFERENCES 

[1] “Committee of Soil Standard Methods for Analyses and Measurements (ed.)” Soil Standard Methods 

for Analyses and Measurements, Hakuyusha, Tokyo (1986). 

[2] Hoang Minh Dao. “Current Vietnam Environment”. Industrial Magazine, No. 2, pp. 13, (2004). 

[3] “Land Use Planning Program in Phung Xa, Thach That, Ha Tay from 2001 to 2010. 2004”. 

[4] Le Duc, Le Van Khoa. “Effect of trade villages' activities for handicraft copper recycle in Dai Dong 

commune, Van Lam district, Hung Yen province to local soil environment”, Soil Science Magazine, No 14: 

48-52, (2001) 

[5] Tessier, A., Campbel, P. G. C. and M. Bisson. “Sequential extraction procedure for the speciation of 

particulate. Analytical Chemistry, No. 51, pp. 844-851, (1979). 

[6] Vietnam standard TCVN 5949-1995 for water, (1995). 

[7] Vietnam standard TCVN 7209-2002 for soil, (2002). 

59


METAL CONTAMINATION IN IRRIGATED AGRICULTURAL 

LAND: CASE STUDY OF NAIROBI RIVER BASIN, KENYA 

P.N. Kamande 1* , F.M.G. Tack 2 

1 University of Nairobi, Department of Land Resources Management and Agricultural Technology, 

P.O. Box 29053-00625, Nairobi, Kenya. Tel: +254.725.371.498. E-mail: pnkamande2002@yahoo.com, 

2 Ghent University, Laboratory for Analytical Chemistry and Applied Ecochemistry, B-9000 Ghent, 

Belgium 

Poster Extended Abstract 

INTRODUCTION 

Farming in Kenya has increased in reaction to the increased population and the 

concomitant demand for food. River water is used for irrigation. In Nairobi river basin, 

industrial effluents and untreated sewage from the Nairobi city council are directly 

discharged into the rivers. In spite of this, farmers continue to use this water for 

irrigation. A recent study by UNEP revealed that Ngong/Motoine River water was 

significantly contaminated with Cr, Cd, Cu, Zn, Pb and Ni [1]. The use of this water for 

irrigation is likely to cause accumulation of significant amounts of metals in agricultural 

soils. This may lead to the accumulation of unacceptably high metal concentrations in 

plants grown on these soils. In this study, metal concentrations and contamination levels 

in agricultural soils of this area were assessed using different chemical extraction 

procedures. 


This study focussed on the areas irrigated with water from the heavily polluted Ngong 

River. Four sampling sites were selected in the farmlands of “Mukuru kwa Njenga” 

slums, within a stretch of about 300 m. Sites 1, 2 and 3 were agricultural sites irrigated 

with river water while site 4 was a non-irrigated (reference) site. The sites were situated 

within 5, 17, 15 and 20 meters from the river, respectively. Sites 1, 2 and 3 were at a 

lower and plain position with respect to river. The reference site was selected on an 

elevated area that was unlikely to have been flooded by the river; it had similar soil 

properties as the test sites and was presumably not predisposed to other sources of 

contamination. At each site, soil was sampled from two points 10 m apart, at 0-20 cm, 

20-40 cm and 40-60 cm depth. 

In this study, it was assumed doubtful whether the farmers were aware of the 

impending environmental and health risks in using polluted river water for growing 

crops. To assess their knowledge base about pollution, a brief interview was conducted 

on farmers, using a simple questionnaire with pointed questions. 

60


Different chemical extraction methods were applied to the soils. These include 

aqua regia extraction for pseudo-total analysis, extraction with 0.5 M HCl for extracting a 

non lithogenic metal fraction, extractions with EDTA and acetic acid, and extraction with 

dilute CaCl2 to determine a highly soluble fraction [2, 3, 4, 5 and 2 respectively]. Surface 

layer samples analysis was triplicated to ascertain the reproducibility of the extraction 

procedures used. To check analytical accuracy, certified reference materials for 

certification of total contents in a calcareous soil (CRM 141) and in a light sandy soil 

(CRM 142 R) were analyzed. 


Most farmers were aware that polluted water affected crop quality. Their awareness and 

innovativeness was evidenced in one case where the farmer tried to purify industrial 

wastewater by allowing it to percolate through the ground and collecting it in a shallow 

well for irrigation. Though the concentration may have been reduced by sorption to soil, 

it is not excluded that the water was still contaminated with soluble elements. Farmers 

defied their knowledge and used the water due to lack of an alternative source of good 

quality water for irrigation. 

The pseudo-total metal contents in the irrigated sites were at least five times higher 

than in the non-irrigated site, with sites 1 and 3 leading. The metal contents (except Ni) 

exceeded normal contents found in most unpolluted soils in the world and were in the 

order Zn>Cr>Pb>Cu>Ni>Cd. The major contaminants were Zn (300-1000 mg/kg), Cr 

(28.5 - 749 mg/kg) and Pb (300 mg/kg). This could possibly be due their extensive use in 

the industries, car garages and informal industries located near the river. Cd in sites 1 and 

3 was slightly elevated compared to normal ranges in soils worldwide (0.07 – 1.1 mg/kg) 

and were in the range 0.94 to 1.37 mg/kg. 

Significant amount of metals were removed by 0.5 M HCl, suggesting their 

association with various more labile fractions in the soil. For sites 1 and 3, median HClextractable 

contents of Cd, Cu, Pb and Zn were between 65 – 80% of the total content. 

For the non-irrigated site, this percentage was between 7 and 18%. The extractability of 

Ni was between 13 – 27%, and only 3% for the non-irrigated site. Despite elevated total 

contents of Cr in the irrigated sites, extractability in HCl remained low in the irrigated 

soils. 

EDTA extracted high contents of Zn (200-700 mg/kg), Pb (35-200 mg/kg) and Cu 

(20-85 mg/kg). In contaminated areas, fractions of the total amount for Cd, Cr and Zn 

were markedly higher than in the reference soil. High EDTA extractable contents in the 

contaminated profiles point to the likelihood that plants grown on these soils would 

accumulate metals in levels above contents in plants growing on uncontaminated sites. 

Except for Zn (200-500 mg/kg) and Ni (3 mg/kg), the metal contents extracted by 

0.11 M acetic acid were below the detection limit of ICP-OES in some profiles. A high 

percentage of Pb (50% of the samples) and Cu (40% of the samples) were also below the 

detection limit. Nevertheless, Cd and Cr recorded measurable amounts in the test sites but 

were below detection in the reference site. These results would suggest that the metals are 

withheld in rather strong complexes, specifically sorbed or occluded in solid soil phase. 

61


The metal content removed with CaCl2 generally fell below the detection limit of 

the ICP-OES. However, there were detectable levels of Zn (0.30±0.14 to 10.2±0.39 

mg/kg) in the surface layers. CaCl2 is a weak extractant, which consists of a neutral salt at 

an ionic strength in the range of typical soil solutions. Low metal levels would indicate 

that metals in the soil are not highly soluble and hence not immediately available for 

uptake by plants. 

CONCLUSION 

The farmers were aware of pollution of Ngong River. However, their knowledge was 

limited to crop quality and did not encompass the degradation of soil quality and health 

hazards related to possible accumulation of heavy metals. With appropriate information, 

farmers may appreciate these hazards 

The metal content of the soils revealed that the use of polluted water for irrigation 

had significantly contributed to contamination of the soils with Cr, Cu and Zn. Although 

chemical extraction suggested that the mobility of the contaminants in these soils is rather 

limited, more general surveys and further investigations of metal uptake by crops are 

needed to evaluate the extent of current hazards. 

This issue indicates the need for implementing management strategies in Kenya to 

prevent and abate soil contamination. To aid in the development of reference values, 

background concentrations of trace elements in Kenyan soils should be established. 

REFERENCES 

[1] UNEP. Outputs of phase I, Nairobi River Basin Project, (1999). 

(URL:http://www.unep.org/roa/Nairobi_River/Webpages/pictures.map7.htm) (24 th July, 2005). 

[2] E.Van Ranst, M. Verloo, A. Demeyer, J.M. Pauwels. Manual for the soil chemistry and fertility 

laboratory. 

Gent University, Faculty of Agricultural and Applied Biological Sciences, Belgium. Pp. 243, (1999). 

[3] R.A. Sutherland. Comparison between non-residual Al, Co, Cu, Fe, Mn, Ni, Pb and Zn released by a 

three step sequential extraction procedure and a dilute hydrochloric acid leach for soil and road deposited 

sediment. Applied Geochemistry, Volume 17, pp. 353-365, (2002). 

[4] G. Rauret, J.F. Lopez-Sanchez, A. Sahuquillo, R. Rubio, C. Davidson, A. Ure, Ph. Quevauviller. 

Improvement of the BCR three step sequential extraction procedure prior to the certification of new 

sediment and soil reference materials. Journal of Environmental Monitor, Volume 1, pp. 57-61, (1999). 

[5] Ph. Quevauviller, M. Lachica, E. Barahona, G. Rauret, A. Ure, A. Gomez, H. Mintau. Interlaboratory 

comparison of EDTA and DPTA procedures prior to certification of extractable trace elements in 

calcareous soils. The Science of The Total Environment, Volume 178, pp. 127-132, (1996a). 

62


Sub-theme : MANAGING GROUNDWATER POLLUTION 

FROM WASTE DISPOSAL SITES 

Kristine Walraevens, Marleen Coetsiers, Kristine Martens, Marc Van Camp 

Laboratory for Applied Geology and Hydrogeology, Department of Geology and Soil Science, Ghent 

University, Ghent, Belgium 

INTRODUCTION: THE WASTE PROBLEM 

Waste constitutes a problem which increasingly demands the attention of scientists, 

engineers, policy makers and the general public. This is partly because the volumes of 

waste are increasing at an alarming rate (due to population growth, but even more to our 

changing life style), and partly because our understanding and appreciation of the hazards 

associated with improperly handled wastes are growing [3]. 

WASTE MANAGEMENT 

In Flanders [8], the strategy to deal with waste consists in the following hierarchy: 

1. waste prevention 

2. waste reuse 

3. waste recycling 

4. waste incineration 

5. waste disposal in controlled dumps. 

Dumping has thus become the last resort, only to be appealed to for waste which cannot 

be managed at lower steps of this ladder. This is in sharp contrast with the past, when the 

usual fate of waste was uncontrolled dumping. The former practice has resulted in widespread 

pollution of soil and groundwater. 

Industrial dump sites have often caused major cases of pollution, but mostly 

restricted to a select group of chemicals. Yet, municipal household-refuse landfill sites 

contribute to pollution of groundwater to a large extent [4], by a wide variety of 

chemicals. 

GROUNDWATER POLLUTION FROM WASTE DISPOSAL 

Rainwater percolating through the waste material in open dumps dissolves soluble matter 

in the waste, becoming more concentrated on its way down. This leachate may leave the 

dump site and contaminate the surrounding soil and groundwater, depending on different 

factors [3]: 

- climatic factors (dry versus humid) 

- depth to the water table and thickness of the unsaturated zone 

63


- the characteristics of the rocks: hydraulic conductivity, potential for adsorption or 

degradation of contaminants 

- type and composition of the waste. 

Interaction of the leachate with the solid soil results mainly in the in-situ pollution of the 

affected soil, whereas groundwater is a mobile medium, transporting and spreading the 

contaminants. Leachate plumes may show lengths of several kilometers [1]. 

MANAGING GROUNDWATER POLLUTION FROM WASTE 

DISPOSAL 

Future waste disposal should be managed in an appropriate way, preventing leachate to 

be produced and to leave the dump. Current practices implemented to reach this objective 

will be discussed. 

Existing cases of groundwater pollution resulting from waste disposal must be 

handled carefully, in order to control the risks and, if possible, restore the area to its 

original state. Different steps are required: 

1. characterization of the groundwater reservoir 

2. characterization and mapping of the pollution plume; geophysical measurements may 

be very helpful [5, 7] 

3. simulation of the groundwater pollution [2, 6] 

4. conception and simulation of remediation schemes [2, 6] 

5. actual remediation 

6. monitoring and follow-up. 

In very specific cases, the actual remediation step may be replaced by natural attenuation 

[4], but then the monitoring and follow-up require double attention. 

Case-studies of groundwater pollution from dump sites will be discussed. 

REFERENCES 

[1] T.H. Christensen, P. Kjeldsen, H.-J. Albrechtsen, G. Heron, P.H. Nielsen, P.L. Bjerg, P.E. Holm. 

“Biogeochemistry of landfill leachate plumes.” Appl. Geochem., 16(7-8), pp. 659-718, (2001). 

[2] K. Martens, K. Walraevens. “Pollution at a dry cleaning site: Modelling of the movement of the 

pollution in groundwater by VOCl with RBCA Tier 2 Analyzer.” ConSoil 2003, Gent. Eight International 

FZK/TNO Conference on Contaminated Soil. Conference Proceedings. Theme B: Identification of Risks, 

pp. 1197-1205, (2003). 

[3] B.W. Murck, B.J. Skinner, S.C. Porter. “Environmental Geology”. John Wiley & Sons, New York 

(ISBN 0-471-30356-9). 535 p., (1996). 

[4] B.M. Van Breukelen. “Natural attenuation of landfill leachate: a combined biogeochemical process 

analysis and microbial ecology approach.” PhD Dissertation, Free University of Amsterdam (ISBN 90- 

9016928-8), 140p., (2003). 

[5] K. Walraevens, E. Beeuwsaert, W. De Breuck. “Geophysical methods for prospecting industrial 

pollution: A case-study.” European Journal of Environmental and Engineering Geophysics, 2, pp. 95-108, 

(1997). 

[6] K. Walraevens, E. Beeuwsaert, M. Van Camp, W. De Breuck. “Groundwater pollution by industrial 

waste disposal: geophysical and hydrogeological case-study.” In: MARINOS, P.G., KOUKIS, G.C., 

64


TSIAMBAOS, G.C. & STOURNARAS, G.C. (eds.). Engineering Geology and the Environment. pp. 2243- 

2248. Rotterdam: A.A. BALKEMA Publishers (ISBN 90-5410-879-7), (1997). 

[7] K. Walraevens, M. Coetsiers, K. Martens. “Large-scale mapping of soil and groundwater pollution to 

quantify pollution spreading.” In: LENS, P., GROTENHUIS, T., MALINA, G. & TABAK, H. (eds.). Soil and 

Sediment Remediation. Mechanisms, technologies and applications. pp. 37-48. Integrated Environmental 

Technology Series. IWA Publishing, London (ISBN 1-84339-100-7), (2005). 

[8] http://www.ovam.be (in Dutch) 

65


CONTAMINATION OF THE MARIMBA RIVER TRIBUTARY, 

ZIMBABWE, WITH CU, PB, ZN AND P BY INDUSTRIAL 

EFFLUENT AND SEWER LINE DISCHARGE. 

Bangira, C * .Wuta, M., Dube, H.M and Chipatiso, L. 

* University of Zimbabwe, Department of Soil Science & Agricultural Engineering, P.O. Box MP167, 

Mount Pleasant, Harare, Zimbabwe 

Tel: +263 4 303211/+263 4 307304 Fax: +263 4 307304 

Abstract 

Correspondence: Email: cbangira@agric.uz.ac.zw 

The rate of industrialization in developing countries is often mismatched with the provision of solid and 

liquid waste disposal and other requisite infrastructural facilities. Consequently, facilities such as sewer 

lines and sewage treatment works become overloaded resulting in frequent pipe bursts and inadequate 

sewage treatment. A study was conducted in Marimba River tributary to assess the contribution of 

industrial effluent and sewer line discharge on the total concentration of Cu, Pb, Zn and P in sediment and 

water. Sediment and water samples were collected at specific points in the tributary during the dry season. 

Heavy metals and P in sediments and water were determined by spectroscopic and colorimetric methods 

respectively. Electrical conductivity and pH were determined using their respective meters. The results 

showed elevated levels of Cu and Zn in sediments immediately after industrial effluent discharge points. 

However, concentrations of Cu, Zn and Pb in water were all below 0.5 mgl -1 . The pH ranged from 7.3 - 8.0 

and 6.2 – 7.4 in water and sediment respectively. Lower concentrations of heavy metals in water were 

attributed to the low insolubility of these metals due to high pH. Significantly higher concentrations of Cu 

and Zn in sediments immediately after the industries were due to industrial effluent discharge that was not 

adequately pre-treated. Phosphates concentration in water exceeded the Standards Association of 

Zimbabwe (1999) limit of 0.5mgl -1 . It was concluded that industrial effluent discharge and burst or leaking 

sewer lines were contributing to the pollution of Manyame River tributary which feeds into Harare’s main 

drinking water source. 

KEY WORDS: Heavy metals, P, industrial effluent, water, sediment, Marimba River 

INTRODUCTION 

In recent years, developing countries have been experiencing rapid industrial growth and 

urbanisation. Such processes bring with it a plethora of social and economic challenges. 

The provision of accommodation to the urban population and the subsequent solid and 

liquid waste disposal facilities are probably some of the major problems faced by cities in 

most developing countries. In Harare, Zimbabwe’s capital city, a phenomenal population 

increase from 310 360 people in 1961, 658 400 people in 1982 to 1 896134 in 2002 

(CSO, 1982; 2002) occurred following the end of the liberation war mainly due to a 

search for employment and partly due to high birth rates. High demand for 

accommodation was then created. The Municipality responded to the housing shortage by 

opening up more residential areas adjacent to the existing ones as in-fill type or on 

agricultural land. People already allocated houses started extending them or constructing 

66


backyard cottages. On one hand small-scale industrial parks built in these areas have their 

liquid waste disposed of in streams. Although the Municipality sanctioned these 

developments, most of them took place illegally. These developments took place without 

or with little upgrading of the sewer reticulation system. Consequently, facilities such as 

sewer lines and sewage treatment facilities became overloaded resulting in frequent pipe 

bursts and inadequate sewage and industrial effluent treatment. Old suburbs such as 

Mabelreign, Greencroft and Bluffhill that were built in the late 1940s and 1950s for 

smaller population have been severely affected by the overloading of the sewer system 

resulting from the increased population and aging sewer reticulation system. Due to nonprohibitive 

fines and the incapacity of the Municipality to regularly monitor effluent 

discharge into water bodies, most industries directly discharge their untreated effluent 

into streams. This study aimed at assessing the contribution of industrial effluent and 

sewer line discharge on the total concentration of Cu, Pb, Zn and P in sediment and water 

in Marimba River tributary. 

Materials and Methods 

The study area is located about 10 km the north west of Harare City and covers the 

Bloomingdale, Bluffhill, Greencroft and Mabelreign residential areas. The Marimba 

tributary passes through the medium and low density residential areas of Bloomingdale, 

Bluffhill, Cotswold Hills and Mabelreign in Harare (Figure 1). In between the tributaries 

is an industrial zone. The main industries in this zone include vehicle servicing and 

repairs, panel beating and spray painting, fuel stations, paint manufacturing, road 

construction and welding. Effluent from these industries is directly discharged into the 

northern sub-tributary. The southern sub-tributary receives mainly domestic effluent from 

the leaking or burst sewer lines and manholes located along the course of the sewer line. 

Manholes serve as relief ponds in case of blockages. Both streams are lined with Typha 

latifolia aquatic plants from the discharge points. The tributaries later converge to form 

one major stream that drains into Marimba River that in turn drains into Lake 

67


LEGEND 

Manhole 

Sampling Site 

Main Road. ............................................ 

Built up area. ............................................ 

Industrial area. ....................................... 

Angola 

Namibia 

SOUTHERN AFRICA 

Democratic 

Republic 

of Congo 

Zambia 

Botsw ana 

South Africa 

HARARE 

Zimbabwe 

Tanzania 

Mozambique 

................................. 

........................... 

River ..................................................... 

N 

# 

68 

300 0 300 600 Meters 

Marimba 

HARARE 

Tynwald 

500 0 500 1000 Met ers 

Figure 1. Location map of the study area. 

7 

8 

Bluff Hill 

6 

9 

5 

4 

2 

3 

10 

12 

11 

Marbelreign 

Greencroft 

Chivero. Lake Chivero is the main source of drinking water for the City of Harare, 

Norton and Chitungwiza. 

The residential areas of Mabelreign, Greencroft and Bluffhill, from where most of 

the sewerage comes from, were constructed in the post World War II era between 1949 

and early 1970s to accommodate an increased number of immigrants from Europe 

(Zinyama, 1993). As such, these areas were for the more privileged and relatively small 

population (Colquhoun, 1993). Their sizes range from 1000-2000m 2 and were thus 

stipulated to have reticulated sewerage system by the urban by-laws. 

Sampling 

Sediment 

River sediments were collected from 12 sites using augers to a depth of 0.1 (refer to 

figure 1). Site 1, 11 and 12 were control sites. At each site three composite sediment 

samples were taken. One sample was composed of 9 sub-samples randomly selected from 

the streambed. The three samples from each site were placed in polythene bags and taken 

to the laboratory for air-drying before chemical analyses. 

1


Water 

Water samples were collected using 1 L plastic bottles previously soaked in 10% HNO3 

to remove any traces of heavy metals. Prior to sampling the bottles were rinsed three 

times with de-ionised water and then stream water. Sampling was done with the bottle 

mouth facing the opposite direction to water flow. A total of three composite water 

samples resulting from the combination of 9 sub-samples were collected from three 

randomly selected positions in the stream. Immediately after sampling, the bottles were 

tightly closed, put in cooler boxes and taken to the laboratory for analyses. 

Laboratory Analyses 

The electrical conductivity and pH of water samples were determined immediately on 

arrival to the laboratory using an Orion pH and electrical conductivity meter respectively. 

About 0.5 L of the water samples were then acidified with 5 drops of concentrated nitric 

acid, filtered with Whatman No. 42 filter paper and the concentration of Cu, Pb and Zn in 

the filtrate was determined using an atomic absorption spectrophotometer. The other 0.5 

L water was analysed for P. Total P in water was measured colorimetrically [Murphy 

and Riley, 1962] after digestion with the aqua-regia. The electrical conductivity was 

measured in a suspension of 1:5 sediment : water. The pH was measured in a 1:5 

sediment: 0.01 M CaCl2 suspension. Total heavy metals in sediments were extracted with 

aqua-regia and then determined using an atomic absorption spectrophotometer. 

Water 


Water pH at the sites affected by contamination was lower than the control sites (sites 1, 

11 and 12). Lower pH is attributed to the discharge of domestic and industrial effluent 

into the stream. Moreover, there was a marked increase in the electrical conductivity of 

water at the industrial sites (sites 4, 5 and 6). Due to high pH of water that precipitates 

heavy metals, the concentration of Cu, Pb and Zn in water at all the sites were below 0.5 

mg l -1 and thus comply with the Standards Association of Zimbabwe [1999] regulations 

for wastewater. 

The P concentration in water (Figure 1) reveals elevated levels of this element 

compared to most natural surface water P concentration of 0.005-0.020 mg l -1 P 

[Chapman, 1998]. Highest values were also recorded at the industrial sites. Although the 

P concentration at other sites were lower than the recommended value of 0.5mg l -1 

[Standards Association of Zimbabwe, 1999] there was a significant difference between 

the control sites (sites 1, 11 and 12) with the other sites that were affected by domestic 

(sewer line discharge) and industrial effluent. Downstream Marimba River total P values 

between 1.67-5.42 ppm have been recorded in water [Hranova and Manjonjo, 2006]. 

Detergents and soaps, which are commonly used for both domestic and industrial 

purposes, contain at least one functional group such as sulphate, sulphonate or phosphate 

groups [Kirsner and Froelich, 1998] and are therefore likely sources of phosphates in 

69


water in this study area. High P concentration in water may also be contributing to the 

growth of aquatic plant, Typha latifolia that starts growing from areas with burst or 

leaking sewer manhole and pipe. Boyd and Hess [1970] found that standing crops of 

Typha latifolia were positively correlated with concentrations of dilute acid soluble P 

(1.0-116 ppm) in hydrosoils and dissolved P (0.02-0.32 ppm) in the waters. 

Sediments 

P concentration (mg l -1 ) 

1 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 

1 2 3 4 5 6 7 8 9 10 11 12 

Sampling site 

Figure 2. P concentration in water at different sites. 

Total P concentration in sediments was significantly higher (Figure 3) at sites that 

received mainly domestic effluent from the leaking manhole of sewer lines or burst pipes. 

This trend implicates detergents and soaps that are widely used for domestic purposes as 

the main sources of P enrichment in the stream. Lower levels of P at site 6 were attributed 

to the low sediment accumulation due to the erosive power of the water from all the 

industries. Earlier studies by Thornton and Nduku [1982] in some Zimbabwean lakes 

showed non-eutrophic lakes to have sediment P concentration of about 0.3ppm whilst 

eutrophic lakes had P concentration greater than 1.0 ppm. The growth of Typha latifolia 

in sections of the stream that were affected by effluent could therefore be a result of P 

enrichment. 

The pH of sediments (Table 1) was in the slightly alkaline range. A significant 

increase in electrical conductivity, however, occurred at the industrial sites and was 

attributed to the direct discharge of soluble salts from industrial chemicals and detergents 

that became associated with sediment particles. Heavy metals (Cu and Zn) in sediments 

showed increased concentration up to 170 mg kg -1 (Figure 3) compared to the control 

sites with less than 60 mg kg -1 . Sediments are good nutrient sinks in rivers. High levels 

of heavy metals in sediments were attributed to the discharge of effluent into the stream 

70


by the electrical, welding, paint and vehicle services industries located along this part of 

the stream. Industrial effluent and sludge are known to contain heavy metals [Alloway, 

1990; McBride, 1995; Nyamangara and Mzezewa, 1999; Zaranyika et al., 1993] The 

concentration of the heavy metals in sediments in a stream that received domestic 

effluent was also less than 50mg kg -1 indicating no enrichment of heavy metals. Pb 

concentration in sediments at all the sites was below 70mg kg -1 and there was no 

particular trend. The use of heavy metals for domestic use is rather limited hence lower 

levels in the sediments. No standard values for heavy metals in sediments exist in 

Zimbabwe. 

P concentration (mg kg -1 ) 

500 

450 

400 

350 

300 

250 

200 

150 

100 

50 

0 

1 2 3 4 5 6 7 8 9 10 11 12 


Figure 3. Mean total P concentration in sediments at different sites. 

71


Conclusion 

Metal concentration (mg kg -1 ) 

200 

180 

160 

140 

120 

100 

80 

60 

40 

20 

0 

1 2 3 4 5 6 7 8 9 10 11 12 


72 

Cu Pb Zn 

Figure 4. Mean heavy metal concentration in sediment at different sites. 

The direct discharge of industrial effluent into the Marimba tributary contributed to the 

enrichment of Cu, P and Zn in sediments. Sewer line leaks and bursts as a result of 

increased population and the discharge of industrial effluent are also enriching the water 

and sediments with P and are polluting Marimba River tributary that feeds into Harare’s 

main drinking water source. Higher P levels in water and sediments may also have 

contributed to the growth of Typha latifolia in the tributary. Regular monitoring of 

industrial effluent and the upgrading of the sewer reticulation system are recommended. 


This research was funded by the University of Zimbabwe Research Board fund 

(3YSL10/0004) for which the authors are very grateful. 

REFERENCE 

B.J. Alloway. Heavy Metals in Soils. Wiley, New York. (1990) 

C.E. Boyd and L.W. Hess. Factors Influencing shoot production and mineral nutrient levels in Typha 

latifolia. Ecology 51 (2): (1970). 

Central Statistics Office. 2002 Census Report. Government of Zimbabwe. (2002)


D. Chapman. Water Quality Assessment: A Guide to use of Biota, Sediments and Water in Environmental 

Monitoring (1998). 2 nd Ed, London. SPON Press 

S. Colquhoun. Present problems facing the harare city council. IN: Zinyama, L., Tevera, D. and Cumming, 

S.(eds) 1993. Harare: the growth and problems of the city. University of zimbabwe publishers. 

R. Hranova and M. Manjonjo. Sewage sludge disposal on land-impacts on surface water quality (2006). In: 

r. Hranova (ed.) Diffuse pollution of water resources: pricinciples and case studies in the southern africa 

region.p272. Taylor & francis group plc, london. 

R.S. Kirsner and C.W. Froelich. Soaps and Detergents: Understanding their composition and effect. 

Ostomy Wound Management 44 (4): 393-397. (1998). 

M.B. mcbride. Toxic metal accumulation from agricultural use of sludge: are USEPA regulations 

protective? Journal of Environmental Quality 24: 5-18. (1995). 

J. Murphy and J. P. Riley. A modified single solution method for determination of phosphate in natural 

waters. Anal. Chim.Acta 27: 31-36. (1962) Cited in: Page, A.L., Miller, R.H., and Keeney, D.R.(eds). 1982. 

Methods of Soil Analysis Part 2. Chemical and Microbiological Properties. Agronomy Series 9. America 

Society of Agronomy, Inc. Madison, USA. 

J. Nyamangara and J. Mzezewa . The effect of long-term sludge application on Zn, Cu, Ni and Pb levels 

in a clay loam soil under pasture grass in Zimbabwe. Agric. Ecosy. Environ. 73: 199-204 (1999) 

Standards Association of Zimbabwe. Zimbabwe standard specification for waste water. Zimbabwe 

Standard No.558:1999. (1999). 

Thornton, J.A. and Nduku, W.K.K. Sediment Chemistry. In: Thornton, J.A. and Nduku, W.K.K. (eds), 

Lake Macllwaine-the Eutrophication and Recovery of a Tropical African Man-made Lake. 1982. P59-65, 

London: Dr W. Junk Publishers 

M.F. Zaranyika, L. Mtetwa, S. Zvomuya, G. Gongoraand and A.S Mathuthu,. The effect of industrial 

effluent and leachate from landfills on the levels of selected trace heavy metals in the waters of upper and 

middle Mukuvisi river in Harare, Zimbabwe. Bull. Chem. Soc. Ethiopia 7 (1) :1-10 (1993) 

Zinyama, L. The evolution of the spatial structure of greater Harare: 1890-1990. (1993). IN: Zinyama, L., 

Tevera, D. and Cumming, S.(Eds) 1993. Harare: the growth and problems of the city. University of 

Zimbabwe publishers. 

73


WATER 

Site Number 

1 2 3 4 5 6 7 8 9 10 11 12 

pH 7.9±0.03 7.8±0.03 NS a 7.5±0.01 7.7±0.0 7.7±0.07 7.7±0.08 7.3±0.01 7.6±0.07 7.4±0.02 7.5±0.01 8.0±0.05 

Conductivity 

(µS cm -1 ) 521±7 542±10 NS 930±74 929±60 887±60 731±27 491.0±22 446±44 507±28 408±25 287±12 

Cu (mgl -1 ) 0.1 0.2 NS 0.2 0.3 0.3 0.3 0.3 0.3 0.2 0.3 0.2 

Pb (mgl -1 ) 0.2 0.2 NS 0.2 0.3 0.2 0.3 0.3 0.3 0.4 0.4 0.3 

Zn (mgl -1 ) 0.1 0.1 NS 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 

SEDIMENT 

pH (CaCl2) 6.7±0.02 6.7±0.03 6.8±0.02 7.3±0.01 6.8±0.05 7.0±0.02 6.2±0.03 7.2 ±0.02 7.4 ±0.03 6.7 ±0.02 6.7 ±0.02 6.6±0.02 

Conductivity 

(µScm -1 ) 451±10 1631±21 2000±51 2116±63 193±15 467±27 375±197 193±7. 1464±34 1630±40 342±9. 320±12 

Ns a - Not sampled because stream section dry 

Table 1. Mean values (± standard error) of selected parameters for water and sediment in Marimba tributary 

74


CONTROLLING PHOSPHORUS (P) MOBILITY IN POORLY P 

SORBING SOILS: DRINKING-WATER TREATMENT 

RESIDUALS (WTR) TO THE RESCUE 

S. Agyin-Birikorang 1* , G.A. O’Connor 1 and L.W. Jacobs 2 

1 Soil and Water Science Department, University of Florida, Gainesville, FL 32611, USA, 2 Department of Crop 

Science, Michigan State University, East Lansing, MI 48824, USA 

* Corresponding author (E-mail: agyin@ufl.edu; Tel.: 1-352-846-5770) 

Abstract 

Surface runoff of nutrients nitrogen (N) and phosphorus (P) from manured agricultural land can be an important 

source of water quality impairment in surface waters worldwide. Excessive concentration of soluble P is the 

most common source of eutrophication in fresh waters. Addition of amendments to reduce P solubility is one of 

the most effective in-situ technologies for remediating P contaminated soils. Abundant evidence indicates that 

drinking water treatment residuals (WTR) are effective amendments. However, little information is available 

concerning the longevity of WTR immobilization. A modified isotopic ( 32 P) dilution technique was used to 

monitor the lability of P in a one-time WTR (114 Mg dry WTR ha -1 ) treated, P-impacted plots in two sites in 

Western Michigan (USA) for seven–and-a-half (7.5) years. At the end of the monitoring period, we conducted a 

runoff study, using rainfall simulation technique on the soils from both sites to assess the long-term 

effectiveness of WTR in reducing dissolved P in runoff and leachate from the soils. Labile P concentrations of 

the WTR-amended soil samples were reduced to ≤ 46 % of the soil samples without WTR amendment, 6 

months after WTR amendment and the reduction persisted for 7.5 years. Application with WTR reduced the 

flow-weighted soluble reactive P concentrations in runoff and leachate in soils from both sites by ~ 60 % and 

dissolved organic P by ~ 45%. Overall, WTR amendment decreased flow-weighted dissolved P concentrations 

by ~ 55 %. We concluded that WTR is an effective amendment to control labile P in P-impacted soils and that 

the WTR immobilized P will remain fixed for a long time. Thus amendment of P-impacted soils with WTR can 

help minimize eutrophication in fresh surface waters. 

INTRODUCTION 

Clean water is a crucial resource for drinking, irrigation, industry, transportation, recreation, 

fishing, hunting, support of biodiversity, and sheer esthetic enjoyment. Eutrophication caused 

by excessive inputs of phosphorus (P) and nitrogen (N) is the most common impairment of 

surface waters worldwide. Eutrophication has many negative effects on aquatic ecosystems. 

Perhaps the most obvious consequence is the increased growth of algae and aquatic weeds 

that interfere with use of the water for fisheries, recreation, industry, agriculture, and 

drinking. 

Application of animal manure in amounts that exceed agronomic P rates often results in 

increased loss of P from agricultural land in surface runoff and potential eutrophication of 

surface waters [21]. Reversal of eutrophication requires the reduction of P and N inputs into 

surface waters. Current strategies used to reduce P transport to surface water include 

conservation tillage, crop residue management, cover crops, buffer strips, contour tillage, 

runoff water impoundment, and terracing. These strategies are effective in controlling 

particulate P but not dissolved P in runoff [21]. Drinking water treatment residuals (WTR) 

that contain Al or Fe oxides can be beneficially used as a best management practice (BMP) to 

protect surface water quality by removing dissolved P from agricultural runoff water. Thus, 

excessive soluble P concentrations can be controlled through the additions of 

environmentally-benign and cost-effective P-sorbing amendments, such as WTRs [5]. 

75


Drinking water treatment residuals are by-products of the drinking water treatment 

process and are physical mixtures of Al or Fe hydr(oxides) that originate from flocculant (Al, 

or Fe salts) additions made during the drinking water treatment [17]. Drinking water 

treatment residuals are usually disposed of in landfills, and can be obtained at minimal or no 

cost from drinking-water treatment facilities. Studies have shown that incorporating WTRs 

into soil reduces excessive soluble P resulting from manure application [3]. Similar studies 

showed that phosphorus solubility in biosolids was reduced by co-application with WTRs [5]. 

O'Connor et al. [17] showed that P movement from P-enriched soils to freshwater supplies 

was reduced when the soils were treated with WTRs. The primary purpose of their study was 

to investigate the ability of three WTRs produced in Florida to reduce soluble P levels in 

Florida soils amended with fertilizer, manure, and biosolids-P sources. Gallimore et al. [7] 

utilized WTRs as a buffer strip (44.8 Mg WTR ha -1 ) applied to a portion of a pasture treated 

with poultry litter. Surface runoff P was reduced by WTR from an average of 15 to 8.1 mg 

L -1 . The authors [7] concluded that the most effective surface application of WTR was as a 

buffer strip. 

Data from various studies suggest that WTRs could be effective amendments to 

improve P retention in poorly P-sorbing soils. Short-term laboratory, greenhouse, and rainfall 

simulation studies have demonstrated WTR efficacy in reducing soluble P concentrations in 

runoff [3], and leaching [5] from areas amended with animal wastes. The long-term stability 

of sorbed P by WTRs has only been qualitatively inferred from lab experiments [12]. Time 

constraints associated with conducting long-term field experiments are the major drawbacks 

in evaluating the long-term fate of sorbed P in WTR-amended soils, and few researchers have 

attempted such studies. The objective of this study was to assess the long-term effectiveness 

of alum WTR (Al-WTR) in reducing dissolved P in runoff and leachate from field soils with 

long histories of poultry manure applications. 

Field layout and amendments application 


Two field sites (sites 1 and 2) located in Western Michigan were selected in 1998 for 

evaluation of WTR effects on P extractability in soils having “very high” soil test P 

concentrations. Both soils have a long-term (> 10 yr) history of heavy chicken manure 

applications (actual application rates unknown). Soil at site 1 was a Granby fine sandy loam 

(sandy, mixed, mesic Typic Endoaquolls) with Bray P1 test levels (265 mg P kg -1 ). Soil at the 

second site was Granby loamy sand (sandy, mixed, mesic Typic Endoaquolls) with Bray P1 

test values of 655 mg P kg -1 . 

A randomized, complete block design was established at each site with four replications 

per treatment and a plot size of 14 m x 30 m. The WTR used in this study was removed from 

lagoon storage, and stockpiled for drying. The dried Al-WTR was applied (114 dry Mg ha -1 ) 

to plots using a Knight ProTwin Slinger, model 8030 V-box spreader, by making three passes 

on each side of the plot, or three round trips. All plots, including the untreated controls, were 

disked (~30 cm) twice following WTR application. Additionally, site 1 was chisel-plowed 

and field cultivated prior to planting on May 5, 1998. Site 2 was moldboard plowed before 

planting on May 4, 1998. Subsequently, both sites were rototilled in April/May, 2000 prior to 

planting to promote more thorough mixing of WTR. Field corn (Zea mays L.) was planted 

each year at both sites. Herbicides and insecticides for weed and pest control typically used 

by cooperating farmers were applied at planting. Fertilizer nitrogen and potash were applied 

76


as needed. The study continued for more than 7 years, but the WTR amendment was applied 

only in 1998. 

Soil sampling 

Surface soils of control and WTR-amended plots from both of the Michigan field study sites 

were first sampled in spring 1998 (time zero) by compositing 20 cores (2.54 cm diameter) 

from the top 30 cm depth of each plot. Additional soil surface samples were similarly 

collected each fall in 1998, 1999, 2000, 2001, 2002, 2003, 2004 and 2005 for analyses to 

monitor changes in labile pools of P following the WTR application. At the end of the 

monitoring period (Fall 2005), surface soils of the control and the WTR amended plots from 

both sites were sampled (~ 20 kg) from the top 30 cm depth of each plot to undertake the 

rainfall simulation study. 

Soil and WTR characterization 

Samples were air-dried and passed through a 2 mm sieve before analyses. Particle size 

distribution was determined by the pipette method [2]. The pH was determined in a 1:2 WTR 

to 0.01 M CaCI2 solution using a glass electrode [13]. Electrical conductivity (EC) was 

determined in a 1:2 WTR to deionized water solution [18]. Soluble reactive P of WTRs was 

measured in a 0.01 M KCl solution at a 1: 10 solid: solution ratio, after 40 d reaction. Total C 

and N were determined by combustion at 1010 C using a Carlo Erba NA-1500 CNS analyzer. 

Total recoverable P, Fe, and Al were determined by ICP-AES (Perkin-Elmer Plasma 3200) 

following digestion according to the EPA Method 3050A [23]. Oxalate extractable P, Fe, and 

Al were determined by the ICP after extraction at a 1: 60 solid: solution ratio, following the 

procedures of [20]. Oxalate-extractable Fe and Al represents noncrystalline and organically 

complexed Fe and Al present in the solid [20]. 

Determination of labile pools of P 

Two grams of each soil sample was placed in centrifuge tubes to which 20 mL of deionized 

water was added, giving a solid-to-solution ratio of 1:10. Two drops of toluene were added to 

each suspension and equilibrated for 4 days in an end-over-end shaker. The samples were 

then spiked with 50 µL of a solution containing 32 P (5 MBq/mL) and returned to the shaker to 

equilibrate for 3 days. At the end of the equilibration period, samples were centrifuged at 

4200 g for 10 min and filtered through 0.2-µm filters (Sartorius). Activities of radioactive P 

in the filtrates were assessed using liquid scintillation counter (Beckman LS 5801). All 

analyses were performed in triplicate and included blanks. The total activity introduced in 

each sample was determined by analyzing spiked solutions, without soil, in parallel with the 

soil suspensions as suggested by [10]. The labile pools (E) of P were determined as reported 

in [8]. 

E = (Csol/C † sol) R * (V/W) -----------------------[1] 

where Csol is the concentration of water extractable P in solution (µg/mL), C † sol is the activity of radioisotope 

remaining in solution after equilibration (Bq/mL), R is the total activity of radioisotope added to each sample 

(Bq/mL), and V/W is the ratio of solution to sample, which in this case was 10 mL/g. 

77


Rainfall simulation experiment 

The rainfall simulation was carried out as prescribed in the U.S. National Phosphorus 

Research Project indoor runoff box protocol [16]. However, the design of wooden runoff 

boxes (100 cm long, 20 cm wide, and 7.5 cm deep) was modified to quantify leaching of P in 

addition to runoff P by adding a second box under the first in a double-decker design. This 

design allows collection of runoff and leachate simultaneously. The boxes were packed with 

5 cm of soils to a bulk density of 1.4 g cm -3 . Soils collected from the Michigan study sites 

(7.5 y after WTR amendment) were pre-wetted to near saturation to control for antecedent 

moisture and to promote runoff in subsequent rainfall simulation. Rainfall simulations were 

conducted three times, at one-day intervals between rainfall events. Boxes were sloped at 3 % 

and rainfall was delivered at 7.1 cm hr -1 from a height of 3 m above the boxes. For each 

rainfall event, the 30 min of runoff, and leachate generated during the entire rainfall was 

collected from each box and the volumes recorded. Subsamples of the runoff were 

immediately filtered (0.45 µm) for analysis. A representative well-mixed sample of the 

unfiltered runoff (~ 250 mL) was also taken from each replicate for analysis. 

Leachate and runoff pH and EC was determined on each sample. Soluble reactive P 

(SRP) was determined on the filtered runoff and the leachate samples colorimetrically [14]. 

Total dissolved phosphorus (TDP) was measured on the filtered runoff and the leachate 

samples after digesting 10 mL of the samples with 0.5 mL 11 N H2S04 and 0.15g of 

potassium persulfate in an autoclave for 1 hr [4]. Total P in the unfiltered runoff sample was 

determined by digesting 5 mL of the samples with 1 mL of 11 N H2S04 and 0.3g of potassium 

persulfate on the digestion block and then diluted by adding 10 ml of water [4]. All digested 

samples were analyzed for P colorimetrically [14]. The iron-oxide impregnated paper strip 

method [15] was used to estimate bioavailable P in runoff waters. 

Particulate phosphorus (PP) was calculated by subtracting TDP from the TP of each 

sample. Dissolved organic P (DOP) was assumed to be the difference between SRP and TDP. 

Flow-weighted P concentrations were determined for the runoff and the leachate by summing 

the product of the P concentrations and volumes for the three runs (P load) and dividing the P 

load by the total volume of the runs. The mass of runoff and leachate P losses (mg) were 

calculated as the product of flow-weighted concentrations (mg L -1 ) and the runoff and 

leachate volume (L) respectively. Total P losses were determined by summing the masses of 

runoff and the leachate P loss. 

Statistical analyses 

Differences among treatments were statistically analyzed as a factorial experiment with a 

randomized complete block design (RCBD), using the general linear model (GLM) of the 

SAS software [19] The means of the various treatments were separated using a single degree 

of freedom orthogonal contrast procedure. 

The data collected from the rainfall simulation study showed great variation about the 

means with coefficient of variation > 60 %. This prompted us to test for normal distribution 

of the data using the Kolmogorov-Smirnov Procedure and the normal probability plots of the 

Statistical Analysis System [19]. The P concentration data were not normally distributed, so 

typical analysis of variance could not be used. Instead, the NPAR1WAY procedure of the 

SAS software with the Kruskal-Wallis test was used. The NPARIWAY procedure is a 

nonparametric procedure that tests whether the distribution of a variable has the same 

location parameter across different groups. The Kruskal-Wallis procedure tests the null 

hypothesis that the groups are not different from each other by testing whether the rank sums 

78


are different based on a Chi-square distribution [9]. This is a powerful and robust test that is 

insensitive to variation among data and the presence of outliers [9]. 


Chemical properties of the WTR and soils used 

The WTR and soils were analyzed for selected chemical properties (Table 1). The pH of 

WTR was near neutral (7.4), and may have resulted from pH adjustment with alkaline 

materials (i.e., calcium hydroxide) during drinking water treatment. 

WTR Site 1 Site 2 

pH 7.4 ± 0.1 6.4 ± 0.2 6.8 ± 0.2 

Sand nd † 

60 ± 3.0 % 76 ± 4.5 % 

Silt nd 28 ± 2.2 % 16 ± 2.0 % 

Clay nd 12 ± 1.4 % 8 ± 0.9 % 

Total C 34,000 ± 

200 

nd nd 

KCl-P 4.0 ± 0.1 22.1 ± 2.3 58.1 ± 5.1 

Bray P1 nd 265 ± 45 655 ± 90 

Oxalate P 570 ± 96 790 ± 7.5 970 ± 8.3 

Oxalate Al 29700 ± 

3603 

2400 ± 21.3 710 ± 8.5 

Oxalate Fe 2300 ± 310 730 ± 8.3 290 ± 0.8 

Total P 800 ± 78 970 ± 47.1 1100 ± 4.3 

Total Al 39700 ± 

5650 

7000 ± 

35.2 

79 

3400 ± 32.5 

Total Fe 9200 ± 545 2700 ± 98.3 1800 ± 6.7 

† not determined 

Table 1: Some characteristics of the WTR and soils used. Values are averages of six replicates ± one 

standard deviation. Values are in mg kg -1 , except pH values 

The EC ranged from 1.21 dS m -1 , well below the 4.0 dS m -1 associated with salinity 

problems [1]. The KCl-P represented only a small fraction of total P, with a mean value of 4 

mg kg -1 . The very low amount of KCl-P in the WTR implies that it would be poor not be 

source of P in soils. Total C value for the WTR was 3.4 %. Total C measured value agreed 

with the range C found for Al-WTRs (2.3- to 20.5 %; [3,12]. Total C determinations may 

overestimate organic C content since the combustion method (temperature 1010 C) measures 

both organic and inorganic C. The high total C levels found in many WTRs may be attributed 

to carbonate additions for pH adjustment during water treatment or additions of activated


carbon, which is used to remove taste and odor from source water. The WTR had C: N ratio 

less than 25, indicating that there was a significant N pool that could be used by plants, if 

WTRs were land applied. A C: N ratio of ~25 is commonly used as the value where 

mineralization and immobilization of an organic amendment are in balance. Total P of the 

WTR was 800 mg P kg -1 , typical of Al-WTRs (300 to 4000 mg P kg -1 ; [3,12] Total P in 

WTRs comes from the raw water purified in drinking water treatment plants and becomes a 

part of the WTR structure. The relatively high total P content of the WTRs is probably due to 

concentration in the WTR after removal from contaminated raw water during treatment. Total 

Al was ~ 40 g Al kg -1 , within normal ranges reported by others (15- to 177 g Al kg -1 ; [3,12]. 

Aluminum (hydr)oxides are sorbents for oxyanions such as phosphate, thus the high Al 

content of the WTR suggests that they will be major sorbents for P. Oxalate extractable P, Fe, 

and Al are usually associated with the amorphous phase of the particles. Oxalate-extractable 

Al values were close to total Al (84 % of the total), suggesting an amorphous nature of the 

WTR. This is consistent with the findings of O’Connor et al. [17] that the traditional 200 mM 

oxalate-extractable P, Al and Fe concentrations are typically 80-90 % of the respective 

WTRs’ total elemental concentrations. Gallimore et al. [17] concluded that the amorphous, 

rather than the total, Al content determines WTR effectiveness in reducing runoff-P. 

The soil samples collected at both sites of the Michigan field have near neutral pH. 

Soils from both sites have very high soil test P (STP) values, but the soil collected from site 2 

had greater soil test P. The high STP values reflect the long history of chicken manure 

application to the fields. The KCl-P accounted for 3.3 and 4.2 %, respectively, of the total P 

contents at site 1 and site 2. The high soluble reactive P concentration at both sites suggests 

that the soil can contribute significantly to P loss in runoff. The soil from site 1 had greater 

total Fe and Al than site 2, suggesting that site 1 had greater potential to sorb excess soil P 

than the soil at site 2. 

Changes in labile pools of P with time 

The isotopic dilution technique has been used to successfully describe P phytoavailability and 

mobility (labile pools of P) in soils [8]. Measured labile P levels in the control plots did not 

change significantly with time in the field, and were ~100 and 220 mg P kg -1 for site 1 and 2 

(Fig. 1), respectively. Site 2 had significantly greater amounts of labile P, consistent with 

greater soil test P levels and coarser texture (Table 1). The high, and nearly constant, labile P 

levels in the control plots reflect the history of heavy manure applications to these soils, and 

portend that soils from both sites could continuously supply large amounts of soluble P in 

runoff over many years. 

80


labile P conc. (mg kg-1) 

300 

250 

200 

150 

100 

50 

0 

t(0) 1998 1999 2000 2001 2002 2003 2004 2005 

Year of sampling 

81 

Site1 control 

Site 1 WTR 

Site 2 control 

Site 2 WTR 

Figure 1: Changes in labile P concentrations with time for the Michigan field samples taken from 

both the control and WTR amended plots at site1 and 2 

Amendment with the WTR significantly (p = 0.015) reduced labile P concentrations at 

both sites (Fig. 1). At site 1, WTR application reduced labile P values from ~ 100 to 50 mg P 

kg -1 6 months after WTR application, and labile P levels continued to decline for another 2 

years. Time series analysis suggests that an equilibrium labile P level (~ 30 mg P kg -1 ) was 

reached around 2.5 years after WTR application. Similar WTR effects were obtained for site 

2. Amendment with WTR significantly (p < 0.001) reduced labile P values within 6 months, 

and the reduction continued for another 4 years. Time series analysis suggested that an 

equilibrium labile P level (~ 75 mg P kg -1 ) was reached around 4.5 years after WTR 

application. The greater time (4.5 years) required at site 2 for the equilibration of WTR effect 

on labile P probably reflects the greater soil test P level, compared to site 1. Nevertheless, 

WTR amendment of either manure-impacted site significantly reduced labile P levels (at all 

times) below the higher levels in the control soils. The reduction in labile P due to WTR 

application is expected to reduce P loss and P pollution potential for these soils. Notable also 

is the longevity of the WTR effect. There was no evidence of release of WTR-immobilized P 

over time as measured by the labile P values. The labile P data demonstrate delayed, but 

steady, reduction in soluble P with time and ultimate reductions of ~ 65 to 70 % relative to 

the control soils. 

The reduction of labile pools of P with time from the WTR-amended plots prompted us 

to assess the changes in Fe and Al concentrations with time. Iron and Al hydroxides, 

especially Al forms in Al WTR, can be major sorbents for oxyanions in soils, such as P. 

Changes in the magnitude of the sorbent pool with time are expected to influence the P 

sorption capacity of the amended soil. For both sites, there was an increase in the 

concentration of oxalate (200 mM)-extractable soil Al and Fe concentrations (Fig. 2) in the 

WTR amended plots, although the concentrations showed great variability over time. The 

WTR amended plots of site 2 exhibited a greater increase in oxalate (200 mM)-extractable Al 

and Fe concentrations, possibly due to the soil’s lower native Al and Fe concentrations (Table 

1). The variability in oxalate extractable- Al and Fe, concentrations over time is attributed to 

sampling variability. Variability in the sorbent (200 mM oxalate-extractable Fe and Al) pool, 

observed with time at both sites (Fig. 25) prompted normalizing the data by dividing oxalate 

(200 mM)-extractable P by the corresponding oxalate Fe and Al concentrations in moles. 

This normalization yields a term, the P saturation ratio (PSR) [11], similar to the degree of P 

saturation (DPS) index, but omits the α factor (α = 0.3-0.5) in the ratio [20]. Small PSR 

values (< 0.1) suggest excess P sorption capacity and limited P lability. The PSR values for


both sites were calculated and statistically analyzed to evaluate subtle differences between 

treatments over time. 

Fe+Al conc. (mmol kg -1 ) 

100 

80 

60 

40 

20 

0 

t (0) 1.5 3.5 5.5 7.5 

Years after WTR application 


Site 2 WT R 


Site 1 WT R 

Figure 2: Changes in oxalate extractable Fe+Al 

with time from both the control and WTR amended 

plots at sites 1 and 2. 

82 

PSR 

1.6 

1.4 

1.2 

1.0 

0.8 

0.6 

0.4 

0.2 

0.0 

t (0) 1.5 3.5 5.5 7.5 

Years after WTR application 


Site 2 WT R 


Site 1 WT R 

Figure 3: Changes in P saturation ratios with time 

from both the control and WTR amended plots at 

sites 1 and 2. 

For site 1, PSR values of the WTR-amended plots did not significantly differ at the 95 

% confidence level from the control (no WTR) plots (Fig. 3). Similarly, aging in the field had 

no significant effect on the PSR values for WTR-amended plots even 7.5 years after WTR 

application; the PSR values remained low and relatively constant (~ 0.3) throughout the 

monitoring period. For site 2 (Fig. 3), PSR values were at least double those of site 1 for both 

control and WTR-amended plots because site 2 had about twice the soil test P and one-half 

the total Fe and Al concentrations (Table 1). Control plots of site 2 had relatively high PSR 

values (> 1), which suggest that site 2 could contribute significant amounts of P in surface 

runoff. Amendment with the WTR significantly (p = 0.015) decreased PSR values 6 months 

after application and, thereafter, remained relatively constant (Fig. 3) at PSR values < 50 % 

of the PSR values of the control samples. There was no significant effect of time, suggesting 

little potential for time-dependent P release from WTR-amended plots. Low native total soil 

Al and Fe concentrations in site 2 soil (Table 1) may have contributed to the positive WTR 

effect on reducing P extractability, as expressed by the PSR concept. In contrast, site 1 soil 

had relatively high amounts of native total Al and Fe concentrations; thus, the WTR 

application rate used was not sufficient to significantly increase total soil Al levels or change 

PSR values. 

Rainfall simulation study 

This study was conducted to confirm WTR effects on WEP and labile P measurements via 

rainfall simulation. Soils used represented samples from one-time WTR-amended fields in 

Western Michigan, 7.5 years after WTR amendment. The masses (mg) of the various forms 

of P lost in runoff and leachate from soil samples collected from both sites are given in Table 

2. 

Generally, there were significantly greater P losses from the soil samples collected from 

site 2 (both the control and the WTR-amended soils), than those collected from site 1 (Table 

2). Results are consistent with the greater soil test P values and greater labile P values for soil


at site 2 than at site 1. Most of the P loss from both sites occurred through surface runoff, 

rather than through leaching (Table 2). 

RUNOFF 

TREATMENT TDP ‡ SRP †† DOP †‡ PP ‡‡ BAP ‡‡† 

Total Runoff 

P 

CTRL 43.6 ± 31.6 40.6 ± 31.2 3.01 ± 2.2 51.9 ± 43.6 52.4 ± 21.4 95.5 ± 52.1 

Site 1 WTR 17.9 ± 8.32 16.0 ± 11.3 1.94 ± 1.37 83.7 ± 77.8 22.5 ± 10.9 102 ± 66.3 

CTRL 65.5 ± 47.3 60.6 ± 46.1 4.85 ±2.99 87.4 ±53.6 76.7 ± 41.6 153 ± 101 

Site 2 WTR 34.1 ± 26.9 31.3 ± 19.8 2.85 ± 2.04 158 ± 112 39.2 ± 24.7 193 ± 89.6 

LEACHATE 

Total 

TOTAL P LOSS 

TREATMENT TDP SRP DOP Leachate P (Runoff + Leachate) 

CTRL 29.0 ± 14.9 12.7 ± 9.32 16.3 ± 11.5 29.0 ± 14.9 124 ± 88.9 

Site 1 WTR 13.3 ± 8.65 5.82 ± 3.96 7.49 ± 5.48 13.3 ± 8.65 115 ± 79.9 

CTRL 44.5 ± 29.5 20.4 ± 16.7 24.1 ± 18.9 44.5 ± 29.5 197 ± 131 

Site 2 WTR 18.7 ± 11.2 7.12 ± 5.34 11.6 ± 8.74 18.7 ± 11.2 

211 ± 156 

† 

Numbers are flow-weighted means of 4 replicates in 3 rainfall events ± one standard deviation 

‡ 

Total dissolved P 

†† 

Soluble reactive P 

†‡ 

Dissolved organic P 

‡‡ 

Particulate P 

‡‡† 

Bioavailable P 

Table 1: Maases† of the various P forms measured in runoff and leachates from both sites of the 

Michigan field study. All values are expressed in mg. 

The total runoff P losses of the samples taken from both sites were dominated by 

particulate P, and greater particulate P loads came from the WTR-amended plots than the 

control plots. The runoff dissolved P at both sites was dominated by soluble reactive P (SRP), 

with dissolved organic P (DOP) occurring in small proportions (< 7 % of TDP). Contrary to 

the runoff dissolved P, the total dissolved P in the leachate had greater absolute values of 

DOP than the SRP. An independent determination of the total dissolved P was carried out on 

the undigested leachate samples using ICP-AES. The values obtained from this independent 

determination were similar to those obtained from the digested leachate samples determined 

colorimetrically. We, therefore, concluded that particulate P loads in the leachate samples 

were negligible and were consequently not determined. The high particulate P concentrations 

observed in the runoff from the soil samples, prompted estimation of ‘bioavailable’ P levels 

in the runoff water, using the iron-oxide impregnated paper strip method [15]. Sharpley [21] 

reported that the transport of BAP in agricultural runoff can stimulate freshwater 

eutrophication Total bioavailable P (BAP) loss was calculated by summing the BAP loads 

from the runoff and the TDP loads from the leachate. Total dissolved P loads were used to 

represent the BAP loads in the leachate on the assumption that the dissolved organic P will 

mineralize and eventually become bioavailable. 

As expected, the total BAP loss from the soil samples taken from site 2 were 

significantly greater than those taken from site 1 (Table 1), consistent with the higher STP 

and labile P values of the site 2 soil. For site 1, the total BAP of the control soils accounted 

for > 60 % of the total P loss, whereas total BAP loss from the WTR-amended plots 

accounted for ~ 25 % of the total P loss (Table 1). Similar behavior was observed for the 

samples taken from site 2, with the total BAP accounting for ~ 55 % in the control and ~25 % 

for the WTR-amended soils (Table 2). The runoff pH and the EC were similar for both the 

83


WTR-amended and the control plots at the respective sites. Runoff pH and EC values were 

similar to those observed for the leachates (data not presented). 

Effects of WTR on P losses 

There were no significant differences between the flow-weighted total P masses of the WTRamended 

plots and the control plots at either site (Table 2). However, the flow-weighted 

TDP, SRP and DOP masses were significantly reduced at both sites in the presence of WTR. 

Conversely, the flow-weighted particulate P masses were significantly greater in the WTR 

amended plots at both sites than the control plots (Table 2). Possibly, the particles detached 

by the rain drops from the WTR-amended plots had greater P enrichment due to the WTR 

immobilization than the soil particles detached from the control plots. Furthermore, the 

greater particulate P masses may be due to the presence of WTR contained in the eroded 

particles, which also contains some P. 

For site 1, application of WTR reduced the flow-weighted SRP masses by ~60 % and 

DOP by ~35% (Fig. 4). Overall, amendment with Al-WTR decreased flow-weighted 

dissolved P mass by ~59 %. Similar results were obtained for site 2. Amendment with Al- 

WTR reduced SRP masses by ~53 % and DOP by ~50 % (Fig. 4), resulting in an overall 

reduction of flow-weighted dissolved P by ~52 %. Earlier studies have shown that WTR 

amendment increased the content of P-fixing Al and Fe concentrations in the soils at both 

sites (Fig. 3). The increased P-fixing capacity of the soils resulted in the decreased TDP 

content. This is consistent with the observation of Elliott et al. [6] that, as the content of Pfixing 

Al and Fe in soils and P sources increases, TDP concentration decreases. The authors 

[6] determined P levels in runoff from soils amended with biosolids and dairy manure, under 

simulated rainfall and concluded that TDP concentrations in runoff can be reduced by adding 

Al and Fe salts to P sources that have high concentrations of water soluble P. 

Amendment with WTR decreased the total (runoff + leachate) flow-weighted TDP 

concentrations from ~ 2.5 mg L -1 to ~ 0.86 mg L -1 at site 1 and from ~ 3.2 mg L -1 to ~ 0.94 

mg L -1 at site 2. The reduced values exceed values (0.01-0.05 mg L -1 ) usually associated with 

eutrophication of surface waters [23], but are below a solution concentration of 1.0 mg L -1 

(3.2 * 10 -5 M) occasionally used as a benchmark. The 1.0 mg L -1 concentration is a common 

goal for wastewater discharges to rivers and streams and has been applied to soils on the 

premise that the discharge of P from soils to water should be held to the same standard [22]. 

Greater single amendment rates (> 114 Mg ha -1 ), or a multiple (yearly) WTR applications are 

likely necessary to reduce TDP concentration to the 0.01-0.05 mg L -1 target concentration 

range. The single application of 114 Mg ha -1 , however, significantly reduced runoff and 

leachate P impacts on water quality. 

A large proportion of the total P load loss in runoff was particulate P (45-73 % of the 

total P losses). Compared to the control plots, greater particulate P losses were found in the 

WTR-amended plots at both sites (Fig. 4). Despite the greater particulate P loads in runoff 

from the WTR-amended plots, flow-weighted ‘bioavailable’ P loads in runoff were 

significantly smaller than those of the control plots (Fig. 32), suggesting that much of the 

particulate P was not bioavailable. Thus, even if WTR-P erodes to surface waters, there 

should be minimal adverse effects on water quality. 

84

percentage od total P mass loss 


100% 

80% 

60% 

40% 

20% 

0% 

Site1 

CTRL 

Site 1 

WTR 

Site 2 

CTRL 

Treatments 

Site 2 

WTR 

Figure 4: Percentages of total P mass loss 

represented by the various P forms. 

PP 

DOP 

SRP 

85 

Mass of bioavailable P (mg) 

140 

120 

100 

SUMMARY AND CONCLUSIONS 

80 

60 

40 

20 

0 

Site1 CTRL Site 1 WTR Site 2 CTRL Site 2 WTR 

Treatments 

Figure 5: Flow-weighted bioavailable P loads in 

runoff from sites 1 and 2. 

The study was conducted to assess the longevity of WTR immobilization. Results from this 

study also showed that amendment with WTR reduced labile P concentration by ≥ 60 % of 

those of the control plots and that 7.5 yr after WTR application, the WTR immobilized P 

remained stable. The data suggest that WTR amendment should reduce P losses from soils, 

and do so for a long time. To confirm this, we utilized rainfall simulation techniques to 

investigate P losses in runoff and leachates 7.5 yr after one-time WTR amendment. 

Amendment with WTR reduced dissolved P and bioavailable P (BAP) by > 50 % from both 

sites, showing that even 7.5 yr after WTR amendment of the sites, the WTR-immobilized P 

remained non-labile. Thus, there is little fear that WTR-immobilized P will be dissolved into 

runoff and leachates to contaminate surface and ground water. The data suggest that WTR 

can be relied upon to control P losses in runoff and leachates, and that even if WTR-P erodes 

to surface waters, the bioavailability of the immobilized P is minimal and will cause no 

adverse effects on the water quality. 

ACKNOWLEDGEMENT 

This study was funded by United States Environmental Protection Agency (EPA Project CP- 

82963801). We wish to express our appreciation to Drs. Hector Castro, John Thomas and Mr. 

Scott R. Brinton (Soil and Water Sci. Dept., Univ. of Florida) for their technical assistance. 

REFERENCES 

[1] N.C. Brady, R.R. Weil. “The Nature and Properties of soils (13 th ed)”, Prentice Hall, NJ, pp. 430-432, 

(2002). 

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Corp. Series Bull. 396. Cooperative Extension Service, North Carolina State University, Raleigh, NC, pp 91-93, 

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solubility and leaching”, Journal of Environmental Quality, 31, pp. 681-689, (2002). 

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Journal of Environmental Quality, 34, pp. 1632-1639, (2005). 

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NY, pp. 787, (1999). 

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treated with lime, beringite, and red mud and identification of a non-labile colloidal fraction of metals using 

isotopic techniques”, Environmental Science and Technology, 37, pp. 979-984, (2003). 

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processes and soil phosphorus availability”, Journal of Environmental Quality, 37, pp. 979-984, (2001). 

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mechanisms and implications. PhD dissertation, University of Florida, Gainesville, FL, (2002). 

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(Eds.), Soil Science Society of America, Madison, WI, pp. 687-683, (1982). 

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waters”, Analytica Chimica Acta, 27, pp. 31-36, (1962). 

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In: G.M. Pierzynski (Ed) “Methods of phosphorus analysis for soils, sediments residuals and waters”, Southern 

Corp. Series Bull. 396. Cooperative Extension Service, North Carolina State University, Raleigh, NC, pp 98- 

102, (2000). 

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studies [Online]. Available at http://www.sera17.ext.vt.edu/Documents/National_P_protocol.pdf (verified May 

12 2006). North Carolina State University, Raleigh, (2001). 

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and Crop science Society of Florida Proceedings 61, pp. 67-73, (2002). 

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phosphorus for protection of surface waters - issues and options”, Journal of Environmental Quality 23, pp. 437- 

451 (1994). 

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86


HEAVY METAL CONTAMINATION OF SOIL AND SURFACE 

WATER BY LEACHATES OF AN OPEN DUMP OF MUNICIPAL 

SOLID WASTE: A CASE STUDY OF OBLOGO LANDFILL IN 

THE GA WEST DISTRICT OF ACCRA, GHANA. 

Abuaku Ebenezer* 

Department of Soil Science, School of Agriculture, University of Cape Coast, Cape Coast, Ghana. 

E-mail: ebentje@yahoo.co.uk; Tel.: + 233 244 73 60 51; Fax: + 233 21 85 03 85 


BACKGROUND 

Municipal Solid Waste (MSW) management constitutes one of the challenging environmental 

problems facing many countries in the developing world in recent times. In Ghana, the 

problem is particularly worrying in the big cities like Accra where an increase in population 

tends to aggravate the situation. Open dumping is the most common method of solid waste 

disposal in most communities in Ghana. However, this presents numerous health and 

environmental problems for communities in which the landfills are located. Leachate from 

the landfill pollutes nearby streams and groundwater and in addition the piles act as breeding 

grounds for rodents and insects which are vectors of human diseases (Rushbrook and Dugh, 

1999) 

Leachate from these MSW landfills has very high contents of a range of organic and 

inorganic substances including heavy metals due to the heterogeneous nature of the waste 

stream reaching the landfill. In mixed (unseparated) MSW, there is a diverse range of other 

materials, some of which are potentially hazardous. Heavy metals in MSW originate from a 

variety of sources such as batteries, consumer electronics, used motor oils, plastics, ink and 

glass products, etc. When present in ground or surface waters, metals may constitute a 

significant hazard for public health and ecosystems. 

The site chosen for the study is important because of its proximity to the Densu River 

which serves as a source of treated water for Accra, the capital City of Ghana. It is also 

located in the catchment of one of the country’s most important Ramsar site. 

OBJECTIVES 

The study is broadly carried out to ascertain the impact of the landfill and its environmental 

pollution on the Oblogo community and its environment in the Ga West District of Accra, 

Ghana. This will involve the determination of heavy metals contained in the leachates coming 

from the landfill and explore the extent to which the leachate has negatively affected the 

quality of Densu River and other aquatic life such as fish. The study also aims at assessing 

the levels of soil contamination due to the landfill and to investigate the effect of the leachatepolluted 

water on the quality of vegetables produced. 

87


HYPOTHESES 

The study is based on the hypotheses that the leachate coming from the landfill contains high 

levels of heavy metals and other contaminants which have affected negatively the quality of 

Densu River and that the quality of both the soil and vegetables irrigated with the leachatepolluted 

river has also been affected significantly. 


The fieldwork involved sampling of leachates, surface water, soil, fish, and vegetables from 

the study site. Measurements which were monitored in the field included temperature, pH, 

and conductivity. Laboratory analyses were also carried out to determine the presences and/or 

levels of heavy metals such as Mercury (Hg), Cadmium (Cd), Copper (Cu), Arsenic (As), 

Silver (Ag) etc using the Nuclear Activation Analysis (NAA) technique. Other physicochemical 

parameters analysed included the Total Dissolved Solid (TDS), Chemical Oxygen 

Demand (COD), and Biological Oxygen Demand (BOD). Questionnaires were designed to 

ascertain the impact of the landfill on the health and socio-economic life of the Oblogo 

community. 

EXPECTED OUTCOME 

It is envisaged that the study will help establish the critical levels of heavy metal 

contaminants in the soil and vegetables irrigated with the leachate-polluted river. The 

presence and/or critical levels of heavy metal contamination of the Densu River and other 

aquatic life such as fish will be known. The effect of the presence of the landfill on the health 

aspects such respiratory diseases, cholera, typhoid etc and the socio-economic life of the 

inhabitants of Oblogo will be ascertained. Recommendations will therefore be made to the 

appropriate governmental agencies for policy formulation and immediate interventions. 

88


WORKSHOP Theme: Soil and Groundwater Pollution and 

Remediation 

Convenors: M. Verloo, K. Walraevens, J. Van De Steene, F. Tack 

CONCLUSIONS 

The workshop consisted of two sub-themes: 

- Managing contaminated soils using phytoremediation 

- Managing groundwater pollution from waste disposal sites 

Sub-theme: Managing contaminated soils using phytoremediation 

Soil contamination is widespread in inhabited areas. Because effective cleanup by pollutant 

removal is financially prohibitive, there is a need to develop alternative affordable strategies 

to manage the contamination. Phytoremediation may prove a valuable option in dealing with 

contaminated land, especially if it can be combined with economic uses such as wood 

production for bioenergy. Erik Meers in his keynote presentation outlined the principles of 

phytoremediation and highlighted recent scientific developments. 

Acid mine tailings may benefit from phytoremediation approaches for long term stabilization 

of the site. However, plant growth may only be realized on these sites after amelioration of 

the physico-chemical parameters using amendments. Tee Boon Goh (Canada) presented 

experiences with various low cost amendments for stabilizing these sites. 

In a next contribution, Tran Thi Le Ha outlined the issue of contamination of agricultural land 

in Vietnam due to various sources of trade village waste. 

Conclusion 

Existing contaminated sites should be managed accounting for the contamination present. 

This management should be designed to prevent any significant hazards to ecosystems or to 

the food web. Phytoremediation is promising in this context provided it can be combined 

with beneficial or economic uses. Appropriate management strategies are extremely site 

specific and additionally depend on economical and sociological aspects. Prevention of new 

soil pollution should be an utmost priority in a country’s policy with respect to soil 

contamination. 

Sub-theme: Managing groundwater pollution from waste disposal sites 

A keynote presentation on this sub-theme was presented by Kristine Walraevens. 

Peter Kamande made an oral presentation on metal contamination in irrigated agricultural 

land in Kenya. River water used for irrigation of fields at the river-side is contaminated by 

various pollutants. The study was focusing on heavy metals in the soil. 

89


Abuaku Ebenezer presented both orally and in a poster a case study of Oblogo municipal 

landfill in the Ga West District of Accra, Ghana. This ongoing study is also focusing on 

heavy metal contamination. Leachates flow overland towards the nearby Densu River, which 

is used for food-supply (fish) and irrigation of vegetable fields. 

Conclusion 

Uncontrolled dumping in open dumps is still common practice in developing countries, both 

for industrial and municipal solid waste. Ensuing contamination problems are affecting the 

local environment and are threatening food quality, and ultimately people’s health. Adoption 

of proper waste management strategies, and of measures for controlling pollution caused by 

the existing open dumps, are highly needed. These require characterization of the siting 

conditions and of the pollution case. 

90


91

Workshop IC-PLR 2006 – Theme B – Integrated soil fertility management 

WORKSHOP THEME B – INTEGRATED SOIL FERTILITY 

MANAGEMENT 

Sub-theme : Use of isotope techniques for nutrient management – 

Isotope biochemistry 

P. Boeckx, K. Denef, O. Van Cleemput 

Paper/poster : Enhancing the agronomic effectiveness of natural 

phosphate rock with poultry manure : a way forward to sustainable 

crop production – S. Agyin-Birikorang, M.K. Akekoe, O.O. Oladeji, 

S.K.A. Danso 

Paper/poster : The effect of liming an acid nitisol with either calcite 

or dolomite on two common bean (Phaseolus vulgaris L.) varieties 

differing in aluminium tolerance – E.N. Mugai, S.G. Agong, H. 

Matsumoto 

Paper/poster : Effect of P fertilisers and weed control on the fate of P 

fertilizers applied to soils under second-rotation Pinus radiata – A.A. 

Rivaie, P. Loganathan, R.W. Tillman 

Sub-theme : Organic farming in the tropics present situation, 

possibilities and challenges – Current research at the research group of 

soil fertility and nutrient management 

Stefaan De Neve 

Paper/poster : Low input approaches for soil fertility management 

verified for semi-arid areas of Eastern Uganda – Kayuki C. Kaizzi, 

Byalebeka John, Charles S. Wortmann, Martha Mamo 

Paper/poster : Amelioration of acid sulfate soil infertility in Malaysia for rice 

cultivation – J. Shamshuddin 

Conclusions 

92


Sub-theme : USE OF ISOTOPE TECHNIQUES FOR 

NUTRIENT MANAGEMENT 

P. Boeckx, K. Denef, and O. Van Cleemput 

1 Laboratory of Applied Physical Chemistry (ISOFYS), Ghent University, Gent, Belgium 

www.isofys.ugent.be, pascal.boeckx@ugent.be, Phone: +32 9 264 60 00 

ISOTOPE BIOGEOCHEMISTRY 

One of the research lines developed at the ISOFYS laboratory is Isotope 

Biogeochemistry. Herein we use advanced, state of the art stable isotope techniques to 

study processes of C and N cycling in terrestrial and aquatic ecosystems. In the following 

two paragraphs we present a summary of our scientific activities and the analytical 

equipment related to stable isotope analysis we have available. 

A first research line deals with N cycling studies. Nitrogen cycling is studied in 

natural and agricultural ecosystems. In natural ecosystems we use natural abundance 

measurements of 15 N in soil profiles and leaf material to develop ecosystem indicators for 

N-cycling (e.g. N openness of ecosystems). Next to that we use 15 N isotope dilution 

techniques in combination with 15 N tracing models to unravel N cycling processes in soil 

systems. Both natural abundance techniques and tracer techniques are also applied to 

study BNF in tropical agriculture. A second research line deals with the use if 13 C in 

combination with physical fractionation techniques for soil organic matter. These studies 

are carried out on a variety of land use systems, going from forest soils over grasslands to 

no-till systems to study C turnover in these systems. A third Isotope Biogeochemistry 

research line deals with the identification of nitrate sources in surface water using stable 

isotope signatures and machine learning techniques. Finally, a fourth axis of expertise we 

develop is the use of biomarkers to assess the link between, on the one hand above 

ground biodiversity or land use, and on the other the microbial community structure in 

the soil and the biogeochemical process they carry out. 

To perform the above mentioned research lines ISOFYS is equipped with state of 

the art advanced mass spectrometry devices. ISOFYS has three Continuous Flow Isotope 

Ratio Mass Spectrometer (CF-IRMS) systems. This equipment is coupled to different 

sample preparation units such as an elemental analyzer, a high temperature elemental 

analyzer, TOC/TN analyzer, trace gas unit, gas chromatograph (GC) and HPLC. The 

combination of three IRMS systems in continuous flow with six sample preparation units 

enables ISOFYS to analyze 15 N, 13 C and 18 O in bulk solid samples; 15 N and 13 C in TOC 

and TN from liquid samples; 15 N, 13 C and 18 O in CO2, CH4, N2O and N2; 15 N, 13 C, 18 O 

and D in specific compounds that can be separated through; and finally 13C in specific 

compounds that can be separated via HPLC. 

93


SELECTED REFERENCES 

[1] P. Boeckx, O. Van Cleemput. "Methane oxidation in a neutral landfill cover soil: influence of 

temperature, moisture content and N-turnover", Journal of Environmental Quality 25: 178-183, (1996). 

[2] P. Boeckx, O. Van Cleemput. "Methane emission from a freshwater wetland in Belgium", Soil Science 

Society of America Journal 61: 1250-1256, (1997). 

[3] Goossens, A. De Visscher, P. Boeckx, O. Van Cleemput. "Two-year field study on the emission of 

N2O from coarse and middle-textured Belgian soils with different land use", Nutrient Cycling in 

Agroecosystems 60: 23-34, (2001). 

[4] L. Kravchenko, P. Boeckx, V. Galchenko, O. Van Cleemput. "Short-term and long-term effects of 

NH4 + on CH4 and N2O fluxes in arable soils", Soil Biology and Biochemistry 34: 669-678, (2002). 

[5] H. Vervaet, P. Boeckx, V. Unamuno, O. Van Cleemput, G. Hofman. "Can δ 15 N profiles in forest soils 

predict NO3 - loss and net N mineralization rates ?", Biology and Fertility of Soils 36: 143-150, (2002). 

[6] F. Accoe, P. Boeckx, O.Van Cleemput, G. Hofman, H. Xu, B. Huang, G. Chen. "Characterization of 

soil organic matter fractions from grassland and cultivated soils via C content and δ 13 C signature", Rapid 

Communications in Mass Spectrometry 16: 2157-2164, (2002). 

[7] X. Xu, P. Boeckx, L. Zhou, O.Van Cleemput. "Inhibition experiments on nitrous oxide emission from 

paddy soils", Global Biogeochemical Cycles 16 (3), DOI. 10.1029/2001GB001397, (2002). 

[8] D. Seghers, E.M. Top, D. Reheul, R. Bulcke, P. Boeckx, W. Verstraete, S.D. Siciliano. "Long-term 

effects of mineral versus organic fertilizers on activity and structure of the methanotrophic community in 

agricultural soils", Environmental Microbiology 5: 867-877, (2003). 

[9] K. Dhondt, P. Boeckx, O. Van Cleemput, G. Hofman. "Quantifying nitrate retention processes in a 

riparian buffer zone using the natural abundance of 15 N in NO3 - ", Rapid Communications in Mass 

Spectrometry 17: 2597-2604, (2003). 

[10] F. Accoe, P. Boeckx, J. Busschaert, G. Hofman, O. Van Cleemput. "Gross N transformation rates and 

net N mineralisation rates related to C and N content of soil organic matter fractions in grassland soils of 

different age", Soil Biology & Biochemistry 36: 2075-2087, (2004). 

[11] H. Vervaet, P. Boeckx, A.M.C. Boko, O. Van Cleemput, G. Hofman. "Gross and net N transformation 

processes in a temperate forest soil: the role of NH4 + and NO3 - immobilization", Plant and Soil 264: 349- 

357, (2004). 

[12] S. De Smet, A. Balcaen, E. Claeys, P. Boeckx, O. Van Cleemput. "Stable carbon isotope analysis of 

different tissues of beef animals in relation to their diet". Rapid Communications in Mass Spectrometry 

18:1227-1232, (2004). 

[13] P. Boeckx, L. Paulino, C. Oyarzún, O. Van Cleemput, R. Godoy. "Soil δ 15 N patterns in old-growth 

forests of southern Chile as integrator for N cycling Isotopes", in Environmental and Health Studies 41: 

249-259, (2005). 

[14] D. Huygens, P. Boeckx, R. Godoy, C. Oyarzún, O. Van Cleemput. "Aggregate and soil organic carbon 

dynamics in south Chilean Andisols", Biogeosciences 2: 159-174, (2005). 

[15] K. Dhondt, P. Boeckx, N. Verhoest, O. Hofman, O. Van Cleemput. "Assessment of temporal and 

spatial efficiency of three adjacent vegetated riparian buffer zones for groundwater nitrate retention". 

Environmental Monitoring and Assessment 116: 197-215, (2005) 

[16] Y. Kewei, R.D. DeLaune, P. Boeckx. "Direct measurement of denitrification activity in a Gulf coast 

freshwater marsh receiving diverted Mississippi water". Chemosphere (accepted), (2006). 

94


ENHANCING THE AGRONOMIC EFFECTIVENESS OF 

NATURAL PHOSPHATE ROCK WITH POULTRY MANURE: 

A WAY FORWARD TO SUSTAINABLE CROP PRODUCTION 

S. Agyin-Birikorang 1 *, M.K. Abekoe 2 , O.O. Oladeji 1 , S.K.A. Danso 2 

1 Soil and Water Science Department, University of Florida, Gainesville, FL 32611, USA; 2 Department of 

Soil Science, University of Ghana, P. O. Box 125, Legon, Accra, Ghana 

* Corresponding author (E-mail: agyin@ufl.edu Tel.: 1-352-392-1804 ext. 328) 

Abstract 

Phosphorus is one of the main limiting nutrients for agricultural production in highly weathered soils 

worldwide. Addition of P inputs is thus required for sustainable crop production. However, high cost and 

limited access to mineral P fertilizers limit their use by resource-poor farmers in West Africa. Direct 

application of finely ground phosphate rock is a promising alternative but its low solubility hampers its use. 

There is therefore the need to look into low cost means of improving the solubility of natural phosphate 

rock to improve their agronomic effectiveness. The objective of this study was to quantitatively estimate 

the enhancement effect of poultry manure on P availability applied from low reactive phosphate rock (Togo 

phosphate rock) to maize grown on highly weathered soils. We utilized two highly weathered soils from 

Ghana and Brazil for this study. In a greenhouse experiment, using 32 P isotopic tracers, the agronomic 

effectiveness of poultry-manure-amended Togo rock phosphate (PR) was compared with partially 

acidulated Togo rock phosphate (PAPR) and triple super phosphate (TSP). Four rates of poultry manure: 0, 

low (30 mg P kg -1 ), high (60 mg P kg -1 ) and very high (120 mg P kg -1 ) were respectively added to a 

constant amendment (60 mg P kg -1 ) of the P sources and applied to each pot of 4 kg soil. A Randomized 

Complete Block Design (RCBD) was used for the experiment in a greenhouse setting and Maize (Zea 

mays) was used as a test crop. The plants were allowed to grow for 42 days after which the above ground 

portion was harvested for analysis. Without poultry manure addition, the agronomic effectiveness, 

represented by the relative agronomic effectiveness (RAE) and proportion of P derived from fertilizer (% 

Pdff) was in the order TSP > PAPR > PR = control (P0). In the presence of low rate poultry manure 

addition, the agronomic effectiveness followed the order TSP > PAPR = PR > P0. However, at the high and 

very high rates of poultry manure addition, no significant differences in agronomic effectiveness were 

observed among the P sources, suggesting that at this rate of poultry manure addition, PR was equally as 

effective as TSP. The study showed that direct application of PR will be a viable option for P replenishment 

when combined with poultry manure at a 1:1 P ratio. Thus a combination of PR and poultry manure can be 

a cost-effective means of ensuring sustainable agricultural production in P-deficient, highly weathered 

tropical soils. 

INTRODUCTION 

Highly weathered tropical soils are often very infertile and exhibit high acidity, which are 

severe constraints for optimum plant growth and crop yields. A very low P status is the 

main limiting factor for sustainable crop production, which is exacerbated through the so 

called ‘‘soil mining’’, i.e. continuous cultivation without addition of P inputs [13]. A 

sustainable management of these soils to increase and sustain crop yields requires a 

proper land use such as long fallows and/or integrated management of organic and 

inorganic inputs [13]. Options for P inputs are organic materials and water-soluble 

mineral P fertilizers like triple superphosphate and diammonium phosphate. 

95


Unfortunately, the use of water-soluble mineral (nearly all imported) P fertilizers by the 

resource-poor farmers in West Africa is limited by their relatively high cost, and supplies 

often unavailable, when needed. Their use has become even more limited due to the 

withdrawal of subsidies on agricultural imports by most governments of developing 

countries, including Ghana. This situation has created a need to consider other alternative 

P sources for sustainable crop production especially in the developing countries. 

Direct application of finely ground phosphate rock (PR), which is locally available 

or imported from neighbouring countries has been suggested as an alternative to the use 

of more expensive imported water-soluble P fertilizers for some crops grown in tropical 

acid soils [10a]. In recent years attention has been focused on the direct use of PRs in 

developing countries, and a number of trials have been conducted under greenhouse and 

field settings [1,2,10a,10b,20,21, 29, 30,31]. The main interest in the use of PR is due to 

its relatively low cost compared to the processed water-soluble fertilizers, and to its effect 

both in supplying P and liming soils in the long-term [10a,15]. Utilization of local PR 

deposits minimizes importation costs and hence saves on foreign exchange. In addition, 

other elements in PR, such as Ca, can improve the soil chemical and physical 

characteristics and contribute to plant nutrition [10a]. These advantages notwithstanding, 

the low solubility of PRs has discouraged its recommendation for direct use as a source 

of P for crops. Most of the P dissolved from PR undergoes immediate adsorption and 

immobilization reactions, whereas only a fraction (30–50% of dissolved P from PR) 

becomes available for plant uptake [8,21]. 

A method to improve the effectiveness of PR such as partial acid treatment with 

H2SO4 or H3PO4 has been suggested. Chien and Menon [10a] reported that partially 

acidified phosphate rocks can be as effective as superphosphate for certain crops and 

soils. Although partially acidified phosphate rocks are considerably cheaper than the 

imported water-soluble P fertilizer, the cost is still beyond the reach of the resource-poor 

small-holder farmers of the developing world. Another method that has been suggested is 

the compaction of PR with water-soluble P fertilizers [11,20,29]. Again, this process is 

slightly expensive to the resource-poor small-holder farmers. One of the cost effective 

options to increase PR solubility that has not been fully exploited is to combine it with 

on-farm organic materials such as farmyard manure (FYM) and crop residues, which 

farmers, particularly resource-poor smallholders, can access easily. Considering the 

hypothetical PR dissolution reaction, resulting in the release of H2PO4 - and Ca 2+ 

[Ca10(PO4)6F2 + 12H + ⇔ 10Ca 2+ + 6H2PO4 - + 2F - ], 

the dissolution of PR can be increased by increasing the supply of protons (H + ) or by the 

continuous removal of the dissolved Ca and P from the dissolution zone [5]. Both of 

these expected processes have been shown to increase the dissolution of PR when acidic 

soil is amended with organic materials [5,18,21, 23,30]. With this amendment, protons 

are supplied by organic acids produced during composting and by the oxidation of 

ammonium to nitrate in the organic material. Thus depending on the amount and quality 

of the material used, it can influence P availability by stimulating microbial activity that 

can, in turn, increase mineralization of soil organic P, produce organic acids that may 

help to acidify and dissolve PR, and reduce P sorption [18]. Although organic 

amendments cannot usually provide sufficient P for optimum crop productivity because 

96


of its low P content, it can increase P availability in high P-fixing soils [18]. Increases in 

P availability are usually attributed firstly to an increase in net negative charges on soil 

colloids that reduce adsorption of applied P, and secondly to organic anions formed by 

decomposing organic manure that can compete with P for the same adsorption sites in the 

soil [18]. 

In addition to providing all the enumerated benefits with regard to organic matter in 

enhancing P phytoavailability from PR, poultry manure, generally, containing high P 

content, which can supply the early P requirement of the crop. By so doing, the plant 

would have better root development to deplete P and Ca in the dissolution zones of the 

PR, and thus enhance further dissolution of the PR. However, quantitative estimation of P 

availability from PR in soil as enhanced by poultry manure has not been reported. 

Because of possible interactions (priming effect) among poultry manure, PR, and soil P, 

use of radioactive 32 P as a tracer is essential to distinguish P availability from soil P, PR, 

or poultry manure. The objective of this study was to use 32 P as a tracer to estimate 

quantitatively the enhancement effect of poultry manure on P availability applied from a 

low-reactivity PR to maize grown on highly weathered tropical soils. 

Site and soil description 


Two highly weathered soil types (from Ghana and Brazil) were collected and utilized for 

the study. The soil from Ghana was a well-drained savanna ochrosol (Ferric Acrisol, 

[14]), obtained from an uncultivated field at the University of Ghana Farm, Legon, near 

Accra. The soil was derived from quartzite schist. The sampling area receives an annual 

rainfall of between 635-1145 mm. The vegetation is mainly grassland with clusters of 

shrubs and grasses which include Panicum maximum, Andropogon gayallus, Sporobolus 

pyramidalis and Cynodon plectoatachus. The soil from Brazil was a clay-textured, typic 

Haplustox [27], with natural vegetation. The soil was obtained from Planaltina de Goiás, 

State of Goiás, Brazil, an area within the Brazilian central "Cerrado" (15 o 14' S, 47 o 42' 

W, altitude 826 m). The soils were collected at the 0-20 cm layer, air-dried, homogenized 

and sieved through a 4 mm screen for pot experiments, and 2 mm screen for laboratory 

analysis. 

Laboratory analysis 

Selected physicochemical properties of the soils used are given in Table 1. Particle size 

distribution analysis was performed using the modified Bouyoucos method as described 

by Day [12]. Soil pH was measured in 1:2 soil: 0.01M CaCl2. Organic carbon was 

analysed following the Walkley and Black oxidation procedure [4]. Total N was 

determined using the Kjeldahl method. Exchangeable basic cations were determined from 

ammonium acetate leachates while exchangeable Al and H were determined from KCl 

leachates as described by Thomas [28]. The effective cation exchange capacity (ECEC) 

was calculated by summing the above exchangeable cations. Extractable P was 

determined by the Bray-1 method and total P content of the soil by digestion with 

97


concentrated sulphuric acid and hydrogen peroxide [9]. In all cases P concentration was 

measured on neutralized extracts by colour development performed by the ammonium 

molybdate-ascorbic acid blue method [24]. 

Selected chemical and mineralogical properties of the PR used are given in Table 2. 

Total P was determined as described in AOAC [6]. The fluoride content was determined 

by means of the F - selective electrode as described by Evans et al. [13]. The PR 

dissolution in neutral ammonium citrate (NAC) and water was carried out as described in 

AOAC (1990) measuring dissolved phosphate by means of the molybdenum blue method 

[24]. Calcium carbonate equivalent and pH were determined as described in ISRIC [17]. 

The mineral composition of the PR was assessed by X-ray diffraction analysis using 

unoriented mounts and Co-Ka radiation on a Siemens D500 diffractometer equipped with 

a graphite crystal monochromator. The CO2-index, i.e. the ratio of intensities of the C–O 

and P–O absorptions, was determined from Fourier Transform Infrared (FTIR) spectra 

using the KBr pellet method (0.35 mg PR and 300 mg KBr compressed at 150 MPa in an 

evacuated die) and a Perkin-Elmer FT-IR2000 instrument. Scanning electron microscopy 

(SEM) using a microprobe technique with energy dispersive X-ray (EDX) was used to 

obtain information about arrangement, composition, size, shape and texture of mineral 

constituents. 

Greenhouse experiment 

Soil amendments used 

Well decomposed poultry manure was obtained from University of Ghana Agricultural 

Research Station, Nungua, near Accra. It was air-dried and crushed to pass through a 2mm 

sieve. The nutrient concentration in the poultry manure was as follows: P, 0.59% N, 

2.3%; and Ca, 3.1 %. The P sources utilized for the study in a finely ground form (100 

mesh) were: Togo phosphate rock (PR), triple superphosphate (TSP) and partially 

acidified Togo phosphate rock (PAPR). The PR was obtained from Hahotoe (Togo) and 

contained 16 % total P with 1.3 % of neutral ammonium citrate-soluble P [2]. The total P 

content of the P sources was determined by dissolving each of them in concentrated HCl 

on a hot sandbath at 80°C and then determining the concentration colorimetrically on 

Philips PU 8620 spectrophotometer. The total P contents were: 11.87% for PAPR and 

19.4 % for TSP. 

Design of the experiment 

Sixty (60) mg P kg -1 of the three inorganic P sources, together with a control [no P 

addition (P0)], were utilized for the study. Four application rates of poultry manure were 

utilized as follows: no poultry manure (M0), poultry manure to supply 30 mg P (M30), 60 

mg P (M60) and 120 mg P (M120) kg -1 of soil calculated on the basis of the total P content 

of the poultry manure. Each of the 16 P source x poultry manure application rate 

combination was randomly assigned to a pot containing 4 kg of the 2 soil types 

respectively. Thus a 3-way mixed factorial experiment with two fixed factors (P source 

and Poultry manure rate) and one random factor (soil type) were combined to yield a total 

of 32 treatments. The pots were arranged n a randomized complete block design (RCBD) 

98


in a greenhouse setting with 3 replicates for each treatment. The isotopic dilution 

technique [32] was then used for the study. 

An aliquot containing 1850 kBq 32 P pot -1 was added to obtain sufficient activity in 

the plant material. To prepare the 32 P-labelled carrier solution, the total activity required 

for the experiments was added as 32 P carrier-free to a known volume of KH2PO4 carrier 

solution with 10 ppm P. Labelling was done by mixing the soil thoroughly with 10 ml of 

the solution containing 32 P phosphate ions. The soils were allowed to equilibrate for 1 

week before adding the unlabelled P fertilizers uniformly to the soil. A control [without P 

fertilizer and poultry manure addition (P0M0)], where only the 32 P carrier solution was 

added was included as reference for the isotopic method. 

Five maize (Zea mays var. Toxipino) seeds were sown in each pot and thinned to 

two after emergence. Pots were watered to 70% of the water holding capacity of the soil. 

Nitrogen, K, Ca, Mg and micronutrients were supplied as P-free Hoagland solution to 

each pot at every 2-weeks interval. The maize plants were allowed to grow for 42 days 

after which the above-ground plant material of each pot was cut into small pieces and the 

shoot dry matter yield was recorded after oven drying at 70 o C to a constant mass. The 

plant samples were burned at 450 o C for 5 h in a muffle furnace and the ashes were 

dissolved in 20 ml of 2 M HCl and filtered. Total P content of the filtered solution was 

determined colorimetrically using the Murphy and Riley [24] method. The 32 P activity in 

the filtered solution was measured by liquid scintillation (Beckman LS 5801) counting of 

the 32 P, by the Cerenkov Effect. Counts were corrected for isotope decay and counting 

efficiency (50%), and expressed in Bq. The specific activity (S.A.) of P was then 

calculated by considering the radioactivity per amount of total P content in the plant and 

expressed in Bq mg -1 P [32]. The percentage of plant P derived from the labeled source, 

and that derived from the soil alone, were calculated according to the 32 P isotopic dilution 

method [32]. Similarly, the proportion (%) and amount (mg P pot -1 ) of P in the plants 

derived from the various P sources, with and without poultry manure treatments was 

obtained directly or indirectly using isotope dilution concepts [32]. Total P uptake from 

the individual P sources alone, and in combination with poultry manure was calculated 

based on the principles followed in Chien et al. [11]. The indices of relative agronomic 

effectiveness (RAE) were estimated based on the shoot dry weight (DMY), and total P 

uptake (Chien et al., 1996) as follows:. 

RAE (%) = [(Y1 – Y0) / (Y2 – Y0)] * 100 

where 

Y1 = yield or P uptake obtained from the P source or its combination, 

Y2 = yield or P uptake obtained from TSP source or its combination, 

Y0 = yield or P uptake obtained from the control 

Statistical analyses 

Differences among treatments were statistically analyzed as a factorial experiment with a 

randomized complete block design (RCBD), using the PROC GLM procedure of general 

linear model (GLM) of the SAS software [26]. The means of the various treatments were 

separated using a single degree of freedom orthogonal contrast procedure. The 

99


relationship between P uptake and rate of poultry manure applied for the P sources was 

determined using a logarithmic function as follows: 

ln Yi = βo + βi ln χ + εi 

where 

Yi was the P uptake obtained with P source i, 

χ was the rate of poultry manure applied, 

βi was the slope of the response function of P source i, 

βo was the intercept, and 

εi was the random error of the fitted model. 

The ratio of any two of the regression coefficients (βi), that describes a Relative Crop 

Response Index (RCRI) [11,25] was estimated as follows: RCRI = βi/βTSP where βi is the 

regression estimate of the tested P source (PR or PAPR) and βTSP is the regression 

estimate of the standard fertilizer used (TSP). This ratio represents the marginal increase 

in P uptake, in proportion of a P source compared with a standard source, when a unit of 

poultry manure is applied. 

Properties of the soils 

RESULTS AND DISCUSSIONS 

The soil obtained from Ghana was a sandy clay loam soil and slightly acid in reaction 

(Table 1). The clay (27.5 %) and sand (51 %) contents were similar to those obtained by 

Acquaye and Oteng [3] for some savanna Ochrosols in Ghana. It was characterized by 

low organic matter, total nitrogen, available P and exchangeable basic cations. The low 

nutrient content of the soil may be due to little nutrient element cycling through plants in 

soils of the savanna zone. 

The soil obtained from Brazil on the other hand was a clay soil and acid in 

reaction with comparatively high organic matter content (Table 1). Consistent with highly 

weathered soils, the soil had very low exchangeable basic cations and low nutrient (N and 

P) content. 

100


Ghana Brazil 

Soil properties 

soil soil 

Sand (g kg -1 ) 510 296 

Silt (g kg -1 ) 215 324 

Clay (g kg -1 ) 275 390 

pH 6.1 4.2 

Organic carbon (g kg -1 ) 10.6 22.6 

Total Nitrogen (%) 0.10 0.32 

Total P (mg kg -1 ) 91 103 

Bray P-1 (mg kg -1 ) 

Exchangeable basic cations (cmol (+) kg 

7.49 6.98 

-1 ) 

Ca 2.27 1.49 

Mg 1.05 1.05 

K 0.85 0.16 

Na 0.34 0.10 

Exchangeable acidity (cmol (+) kg -1 ) 1.45 6.58 

Table 1: Some physical and chemical properties of the soils used 

Characteristics of the Phosphate Rock 

101 

pHH2O 7.4 

Total P (%) 16.1 

Ca (%) 33.2 

F (%) 1.6 

Ca:P-ratio 2.1 

F:P-ratio 0.16 

CaCO3 (%) 5.4 

Si (%) 5.2 

NAC-P † (%) 1.3 

WS-P ‡ (%) 0.02 

a-cell (nm) 0.938 

c-cell (nm) 0.692 

Crystal size (nm) 400 

CO2-index 0.29 

Table 2: Selected chemical and 

mineralogical the phosphate rock used 

† Neutral ammonium citrate-soluble phosphate. 

‡ Water-soluble phosphate. 

Chemical, mineralogical and reactivity characteristics of the PR used are shown in Table 

2. The data suggests that PR is a carbonate substituted fluorine deficient francolite. The 

low CO2-index corresponding to a low degree of carbonate substitution is consistent with 

the a-cell values, which indicate very low carbonate substitution. Moreover, the high acell 

values indicate very low reactivity, which is consistent with the measured low 

Neutral ammonium citrate (NAC) solubility. The large crystal size of the PR is also 

noteworthy in relation to reactivity [10b]. The low reactivity of Togo PR, and hence its 

unsuitability for direct application as P fertilizer, has been confirmed in numerous 

laboratory and greenhouse studies [1,2,21,25]. 

Effects of the P sources 

Despite the variation among the soils used in terms of differences in texture, pH, organic 

carbon content, etc; the effect of poultry manure on PR availability followed similar 

trends. Therefore only the data obtained from the soil of the Savanna zone of Ghana 

(Ferric Acrisol) are presented here. This soil was selected for explanation purposes 

because it showed the clearest trends. 

The shoot dry matter yield (DMY), total P uptake, P derived from the applied P 

source (Pdff), obtained from the applied P sources, without poultry manure addition are 

presented in Table 3. The relative agronomic effectiveness (RAE) values calculated, 

based on DMY and total P-uptake from the applied P sources are also included in Table 

3. Without P addition (P0), DMY and P uptake for the crop were low, consistent with the 

low bioavailable P content of the soil. Addition of TSP and PAPR significantly increased 

DMY and P uptake over the P0 and PR treatments. No significant difference was


observed between the PR and P0, suggesting that the PR did not release adequate P to 

increase yield over the P0. Similar results have been previously reported when PR was 

utilized in some acid to near-neutral soils of the interior savanna and forest zones of 

Ghana [1,2,25]. 

The Pdff, which is estimated by isotope dilution technique, was also used to 

evaluate P uptake from the applied P sources. This technique is reported to be the most 

sensitive method for P uptake assessment from applied P fertilizers [32]. Similar to the 

DMY and P uptake, the percentage Pdff of the P sources followed the order: TSP > 

PAPR > PR (Table 3). As expected, the RAE values calculated based on total P uptake 

also showed, clearly, highest effectiveness of TSP followed by PAPR. This index was 

found to be a good parameter to compare differences in effectiveness between P sources 

[11,25]. The RAE calculated based on DMY indicated that PAPR was ~ 55 % as 

effective as the water soluble TSP in increasing yield of the maize crop while PR was 

only ~ 9 % (Table 3). Thus, the untreated PR was far inferior to the TSP and PAPR in 

increasing dry matter yield and P uptake of the crop. 

Treatment DMY P uptake Pdff % RAE based on 

g pot -1 mg pot -1 % DMY P-uptake 

M0P0 3.1 ± 0.7 13.4 ± 2.4 0 0 0 

M0PR 3.7 ± 1.1 14.5 ± 2.7 4.3 8.8 5.7 

M0PAPR 7.0 ± 1.4 19.5 ± 2.0 35.3 54.6 31.6 

M0TSP 10.8 ± 1.8 32.7 ± 4.2 72.6 100 100 

M30P0 5.1 ± 0.4 27.6 ± 3.4 0 0 0 

M30PR 7.5 ± 1.6 38.7 ±4.6 38.9 40.1 38.7 

M30PAPR 7.9 ± 2.1 40.2 ± 5.7 53.2 46.8 43.9 

M30TSP 11.2 ± 2.4 56.3 ± 5.3 73.2 100 100 

M60P0 7.9 ± 1.3 34.9 ± 4.2 0 0 0 

M60PR 11.3 ± 1.8 70.5 ± 8.1 72.7 84.4 85.4 

M60PAPR 11.4 ± 2.1 72.7 ± 6.5 70.9 86.3 91.0 

M60TSP 12.1 ± 2.4 76.1 ± 7.2 74.4 100 100 

M120P0 8.1 ± 1.6 53.4 ± 6.2 0 0 0 

M120PR 11.6 ± 1.9 73.1 ± 5.7 74.1 80.4 64.6 

M120PAPR 11.7 ± 2.2 74.1 ± 8.2 73.8 83.7 67.9 

M120TSP 12.2 ± 2.1 83.9 ± 7.6 75.6 100 100 

Table 3: Dry matter yield, P uptake, Pdff and RAE of the maize plant fertilized with the P 

sources, with and without manure addition. Values are average of three samples ± one standard 

deviation 

Effect of poultry manure addition 

Mixing the various P sources with poultry manure significantly increased the DMY, P 

uptake and Pdff (Table 3) over those applied without poultry manure addition (M0) 

(Table 3). In the presence of low rate (M30 = 30 mg P kg -1 ) poultry manure addition, the 

DMY of the maize shoot of the PR treated plots increased from 3.8 to 7.5 mg pot -1 , while 

the total P uptake increased from 14.5 to 38 mg pot -1 . The percent P derived from the PR 

increased by nearly 10-fold (Table 3). Thus in the presence of M30, RAE calculated from 

102


both DMY and P-uptake followed the order TSP > PAPR = PR > P0 (Table 3). At the 

high (M60 = 60 mg P kg -1 ) and the very high (M120 = 120 mg P kg -1 ) rates of poultry 

manure incorporation, about 4-fold increase in DMY of the maize shoot over those of the 

PR treatment without poultry manure addition was observed (Table 3). Nearly 5-fold 

increase in total P uptake over the PR plots without manure addition was also observed. 

At these rates of manure application (M60 and M120), no significant differences in 

agronomic effectiveness were observed among the P sources, suggesting that at this rate 

of poultry manure addition, PR was equally as effective as TSP (Table 3). The PR mixed 

with poultry manure at a ratio of 1:1 increased the Pdff of the maize shoot from ~ 4 to ~ 

73 % and DMY also increased from ~ 4 to 11.3 g, and gave RAE (calculated from P 

uptake) of ~ 84 %, which was similar to that of PAPR-poultry manure treatment and 

significantly greater than the PAPR treatment that received no poultry manure 

incorporation (Table 3). The high Pdff obtained from the PR-poultry manure mixture 

suggested an increased release of P from an otherwise unreactive PR. The DMY and P 

uptake by the maize shoot in the PR-poultry manure treatment were significantly greater 

than those obtained for the poultry manure applied alone (Table 3). This suggested that P 

availability from the PR-poultry manure to the maize crop was derived from the two 

materials. A two-way analysis of variance (ANOVA) showed a significant interaction 

between the PR and poultry manure. 

The calculated values of P uptake using the isotopic dilution principles [11], 

presented in Fig. 1, were used to derive the regression coefficients (β) needed to calculate 

the relative crop response index (RCRI) for the various P sources. The estimated 

regression coefficients and RCRI for P uptake obtained for the various P sources are 

presented in Table 4. The RCRI represents the marginal increase in P uptake in 

proportion of a source compared with a standard source (TSP), when a unit of poultry 

manure is applied. 

Source β1 RCRI (%) 

TSP 0.12 100 

PAPR 0.21 175 

PR 0.37 308 

Table 4: Calculated values of the semi-log regression coefficient (β1) and the relative crop 

response index (RCRI) of the P sources as a function of manure addition. 

The RCRI vales indicated that the increase in P uptake as enhanced by poultry manure 

was ~ 3 times that of TSP and ~ 2 times that of PAPR (Table 4). The enhancing effect of 

poultry manure on P availability was thus greatest on the PR and that the effect decreased 

with increasing water-soluble P contents of the P sources. In the case of the TSP and 

PAPR, the lower influence of the poultry manure than the PR-poultry mixture may be 

due to the high water soluble P content (50% and 80% respectively for PAPR and TSP), 

which, possibly, already had priming effect of supplying P for early development and 

growth of the maize crop [7]. This is consistent with the results of Zaharah and Bah [31] 

who reported that green manure (organic matter) generally increased the solubility of less 

reactive PRs and depressed that of the more reactive ones. The greater enhancement 

effect of the poultry manure on the PR than on the PAPR and TSP may be explained by 

two possible mechanisms. Firstly, the release of organic acids such as citric and oxalic 

103


acids during hydrolytic decomposition of the poultry manure may effectively chelate 

Ca 2+ ion and lower its activity in the solution [15], or the organic acids so produced may 

solubilize the PR and render the P available to the maize plant. Secondly, the effect of the 

poultry manure may also be due to self-liming caused by mineralization and subsequent 

release of basic cations [23] and/or a release of OH - ions which may raise the pH of the 

soil-poultry manure system and facilitate the release of P [18]. 

To test which one of these processes was responsible for the interaction, the soil 

was mixed with PR and poultry manure in a ratio of 1:1, maintained at 60% water 

holding capacity and incubated for 6 weeks. A control treatment in which the soil was 

mixed with PR but without poultry manure was also included. At the end of the 

incubation period, the pH of the incubated samples was determined. The pH dropped 

from 6.2 in the soil mixed with PR alone (control) to pH 5.1 in the soil-poultry manure 

mixture. A drop in pH suggested a release of organic acids which rules out the possibility 

of self-liming due to the presence of the poultry manure. 

We also hypothesized that P contained in the poultry manure will supply the early P 

requirement of the crop, which will enhance root development of the crop to deplete P 

and Ca 2+ in the dissolution zone. Such reaction is expected to increase P availability from 

the PR. The result of the study shows that poultry manure addition to the soil alone, 

enabled the crop to significantly increase P uptake by the crop (Table 3). This 

observation supports the hypothesis that P availability from the manure also enhanced the 

efficiency of PR in increasing P uptake. 

Differences between P uptake from the PR applied alone and P uptake from PR 

amended with different rates of poultry manure represented a quantitative estimation of 

the contribution of the poultry manure to the PR. In spite of the geometric increase of the 

P rate of the poultry manure mixed with the PR, the corresponding contribution to P 

availability from the PR was rather more of an exponential increase. For example, the 

increase in P uptake from the PR due to the poultry manure was 56 mg pot -l for M60 and 

59 mg pot -1 for the MI20 treatment. Thus, doubling the P rate of the poultry manure mixed 

with PR did not result in corresponding contribution to P uptake. This may be attributed 

to common Ca 2+ ion since, both PR and poultry manure contain some amounts of Ca 

which may increase the Ca 2+ ion content in the soil solution and prevent dissolution of 

the rock phosphate [23]. It is therefore, uneconomical to mix very large amounts of the 

poultry manure, with the PR. 

The marginal increase in P uptake (Fig. 2) was calculated as the derivative of the 

total P uptake with respect to P application rate of the poultry manure mixed with the PR. 

The maximum increase in P uptake was observed at M60 (1:1 PR manure ratio), after rate 

diminishing returns in P uptake was observed. The result suggest that the most 

economical returns in terms of P-uptake and possibly DMY is achieved when unreactive 

Togo PR is mixed with poultry manure at 1:1 P ratio. 

104

P uptake (log mg pot -1 ) 

5 

4 

3 

2 

1 

0 


TSP: LN Y = 3.7 + 0.12 LN (X) R 2 = 1.0 

PAPR: LN Y = 3.2 + 0.21 LN (X) R 2 = 1.0 

PR: LN Y = 2.6 + 0.37 LN (X) R 2 = 0.99 

0 1 2 3 4 5 6 

Manure rate (log mg P kg -1 ) 

TSP 

PAPR 

PR 

P0 

Figure 1: Linearized relationship between the manure 

application rates and P uptake from the P sources 

105 

Marginal P uptake (kg soil pot -1 ) 

SUMMARY AND CONCLUSIONS 

1.80 

1.60 

1.40 

1.20 

1.00 

0.80 

0.60 

0.40 

0.20 

0.00 

60 

0 50 100 150 

Manure rate (mg P kg -1 ) 

Figure 2: Increase in P uptake from PR per unit 

increase in manure added 

The 32 P isotope dilution technique was an efficient tool to provide quantitative 

measurements of P uptake from the P sources studied for assessing the enhancement 

effect of poultry manure on P availability from PR. Unreactive Togo PR was found to be 

an ineffective P source for the 6-week-old maize plants grown on highly weathered acid 

to near-neutral soils. Addition of poultry manure to PR enhanced P uptake from the PR 

under the experimental conditions. Mixing an unreactive Togo rock phosphate with 

poultry manure in a 1:1 P ratio and applied to some highly weathered acid to near-neutral 

soils was more efficient in increasing DMY and P uptake of the maize shoot than using 

PAPR, and comparable to TSP (TSP = M60PR = M60PAPR > PAPR > PR). This finding 

is of relevance to local agriculture where a low input technology such as mixing 

unreactive PR with poultry manure can increase crop yield. The cost of mixing poultry 

manure with Togo PR is likely to be far lower than partial acidification since H3PO4 and 

H2SO4 needed for the process are imported and are extra cost to crop production. With 

the improvement of the poultry industry in most developing countries, including Ghana, 

disposal of poultry manure will sooner than later become a major environmental issue. 

Thus the beneficial use of poultry manure to improve the P status of the cropland will 

solve the anticipated disposal problem as well. 

Further field trials under a variety of soil, climatic and agronomic management are 

needed to test further the hypothesis of the enhancement of P uptake in PR-manure 

mixture. Also, field-grown plant species may differ widely in their abilities to access 

poorly available soil phosphorus, thus plant species’ effect is worthy of investigation.


ACKNOWLEDGMENTS 

This study was funded in part by the Ministry of Food and Agriculture, Ghana, through 

the National Agric. Research Programme (NARP). We wish to express appreciation to 

Profs. E. Owusu-Bennoah (CSIR, Ghana) and L.R.F. Alleoni (Univ. de Sao Paulo, 

Brazil) for their collaboration, and to Mr. Victor O. Edusei (Soil Sci. Dept., Univ. of 

Ghana), and Mr. Jeff Said (Agronomy Dept., Univ. of Florida) for their technical support. 

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availability from Patos phosphate rock for Eucalyptus: A study with P-32 radiotracer”, Scientia Agricola 

63, pp. 65-69, (2006). 

[30] M.W. Waigwa, C.O. Othieno, J.R. Okalebo. “Phosphorus availability as affected by the application of 

phosphate rock combined with organic materials to acid soils in western Kenya”, Experimental Agriculture, 

39, pp. 395-407, (2003). 

[31] A.R. Zaharah, A.R Bah. “Effect of green manures on P solubilization and P uptake from phosphate 

rock”, Nutrient Cycling in Agroecosystems, 48, pp. 247-255 (1997). 

[32] F. Zapata, H. Axmann. “ 32 P isotopic techniques for evaluating the agronomic effectiveness of rock 

phosphate materials”, Fertilizer Research, 41 pp. 189–195 (1995). 

107


THE EFFECT OF LIMING AN ACID NITISOL WITH EITHER 

CALCITE OR DOLOMITE ON TWO COMMON BEAN 

(Phaseolus vulgaris L.) VARIETIES DIFFERING IN 

ALUMINIUM TOLERANCE 

E .N Mugai 1* , S.G Agong 1 and H. Matsumoto 2 

1 Horticulture Department, Jomo Kenyatta University of Agriculture and Technology, P.O Box 62000 

Nairobi, Kenya, 3 Research Institute for Bioresources, Okayama University, Chuo Kurashiki 710, Japan 

Email: nmugai@yahoo.com or njue@jkuat.ac.ke Tel.+254 -722-337605 

Abstract 

Two common bean (Phaseolus vulgaris) varieties, Rosecoco (GLP 2) and French bean (cultivar ‘Amy’), 

previously shown to differ in Al tolerance were tested for their response to liming with either calcite or 

dolomite in potted strongly acid, low fertility humic Nitisol. Dry matter yield, as a response to liming was 

highest at liming pH 5.6 for both varieties and lime types. However, French bean responded more to liming 

than Rosecoco at 102% and 102% (calcite), 129 %and 102 % (dolomite) of control respectively. Higher 

calcite liming (pH 6.8) reduced growth and was attributed to Mg deficiency by competition during uptake 

of Ca. Differential Al accumulation in the two varieties was higher in shoots of French bean but lower in 

roots an indication that one of the possible mechanisms of Rosecoco’s Al tolerance is confining Al to roots 

other than in shoots. However, Al uptake decreased in roots and shoots of both varieties with increasing 

levels of liming. Ca in the shoots increased with increasing liming levels but was higher in calcite than in 

dolomite treatments. Mg contents did not show any significant increases with liming with calcite but 

increased with dolomite liming levels. Rosecoco was more efficient in the uptake of Ca and Mg than the 

French bean. Therefore, it is concluded that there exists a varietal difference in Phaseolus vulgaris response 

to soil acidity and associated hazards and is therefore possible to select and breed/introduce Al tolerant 

cultivars for the acid soils of Kenya and that although both types of limes can be used to reduce the 

hazardous effect of acidity, dolomitic limes have an advantage in due to the additional Mg nutrition. It is 

therefore recommended that to achieve the highest crop yield on acid Nitisols, only dolomitic limes should 

be applied to a pH of around 5.6. 

INTRODUCTION 

In Kenya, acid soils with a pH of 5.0 or less comprise some or all Nitisols, Acrisols, 

Ferralsols, Cambisols and Andisols [3, 16]. These soils are estimated to cover an area of 

about 5 million hectares [16]. They are located in the Highlands where the climate is 

suitable for the intensive cultivation of many crops including the main source of protein 

to majority of Kenyans, the common bean. Continuous cultivation and use of soil 

acidifying fertilisers especially those containing ammonium has contributed to further 

acidification of these soils. 

Although the hazard of soil acidity is obvious, the small-scale farmers have not 

adapted the culture of ameliorating it through liming, nor is the information available 

regarding relevant soil properties and the liming requirements for a particular crop. In 

Kenya, two cheap types of lime are available - calcite (CaCO3) and dolomite 

108


(CaMg(CO3)2. There are no comparative studies yet done to test the efficacy of the two 

lime types in the management of specific acid soils of Kenya. 

The objectives of this research were to: (i) Characterise the acidity and related 

fertility properties of the acid humic Nitisol, (ii) Determine the optimum liming 

requirement by either calcite or dolomite and (iii) Determine the differential effect of 

liming with either calcite or dolomite on the growth and nutrition aspects of the common 

bean. 

Soil sampling and analysis 


Soil (0-15cm) was obtained from a humic Nitisol [3,14], in the tea-growing zone (altitude 

2150m, Agro-climatic zone I-6) of Gatundu division, Thika District, Kenya. The soil was 

air dried, sieved through 2 mm and mixed. A sub-sample of the soil was analysed for pH 

(1:2.5 soil/water; 1:2.5 soil/0.01 CaCl2 solution); extractable Al (1N KCl) [2]; available 

phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) [8]. P was determined 

by the molybdate blue method and measured by spectrophotometry, K by flame 

photometry and Ca and Mg by the atomic absorption spectrophotometry (AAS). Organic 

carbon was determined by the wet oxidation method [7]. Cation exchange capacity was 

determined by ammonium acetate method [2] and effective cation exchange capacity 

(ECEC) by sum of cations (including Al) extracted by unbuffered 1N KCl. 

The summary results of the soil analysis are presented in Table 1. The soil is 

strongly acidic. The Al content is high reaching a saturation of about 50%. The high 

organic carbon is an indication of a lower rate of humification due to high acidity of the 

soil and the cool climate of the area. The chemical soil fertility is low except for K. 

Mapping 

unit 

(FAO) 

humic 

Nitisol 

pH 

water 

pH 

CaCl2 

CECac 

(cmole 

(+)/kg 

ECEC 

(cmole 

(+)/kg 

Organic 

Carbon % 

3.95 3.4 24.8 11.4 1.9 1. 

6 

Table 1: Selected soil properties of the test soil 

Neutralizing equivalence of limes 

109 

Available nutrients 

(cmole (+)/kg 

K Ca Mg P 

(ppm 

0.6 

7 

0.2 

5 

Extractable 

Al (cmole 

(+) /kg 

) 

11.0 5.11 

The neutralizing equivalence of both calcite and dolomite as calculated for pure calcium 

carbonate was assessed by the method of Jackson [2]. Briefly, 1g of the lime were reacted 

with 1N HCl. After dilution, to 100 ml and boiling, the mixture was cooled and backtitrated 

with 1N NaOH using phenol-phthalein as indicator and calcium carbonate 

equivalence calculated accordingly. Calcite and dolomite were found to have a 

neutralizing equivalence values of 91.6 and 87 respectively.


Estimation of liming requirements and plant culture 

Liming materials were local merchants. Estimation of liming requirements was from a 

calibration curve of pH against lime after incubating wet soil (1: 2.5 soil: water) with the 

varying amounts of liming materials (calcite and dolomite) for seven days [1]. Liming 

levels were 0, 6.0, 16.0 and 32 and 0, 6.0, 17, and 34 g/4 Kg soil of calcite and dolomite 

respectively, to attain pH levels 3.95, 5.1, 5.6 and 6.8. The liming materials were 

thoroughly mixed with the soil before potting. 1.32 g of diammonium phosphate (DAP) 

fertiliser equivalent to 200Kg (DAP) per hectare was mixed with top 5cm potted soil 

before planting. Three uniform 2-leaf seedlings previously pre-germinated in sterile sand 

were planted per pot. After a week of growth thinning was done to leave one seedling per 

pot. The liming treatments including the control were replicated three times and 

randomly placed on raised bench in greenhouse. Distilled water was used for basal 

irrigation. After one month the plants were harvested, washed off the soil with running 

tap water and rinsed with distilled water. The plants were then dried for 24 hours at 80 0 C 

in a blow oven. The dry shoot and root were then weights were then weighed separately. 

0.5g of each was then ground in a plant mill and ashed in a furnace at 550 0 C. The ash 

was dissolved in 5 ml of 6N HCl, dehydrated, then dissolved again in 2 ml of 6N HCl and 

diluted to 100ml. Total Al, Ca and Mg in both shoots and roots and were then analysed 

by same methods as for the soil. 

Plant growth versus liming 

RESULTS 

Table 2 presents the shoot and root dry weights of the two bean varieties against liming 

type and levels. The shoot and root dry biomass of the two bean varieties was 

significantly improved under liming irrespective of the lime type. The highest growth in 

both shoots and roots was attained at pH 5.6 across the varieties. In the un-limed soil the 

French bean variety exhibited a significant suppression of growth as compared with 

Rosecoco. Liming with calcite produced significantly less growth compared to that of 

dolomite across the two varieties and at the various levels of liming. In both types of 

liming, growth increase declined for both varieties at pH 6.8 although it was higher in 

French bean than in Rosecoco. 

The differential variety response to the two types of lime was also assessed by 

computing the relative whole plant growth against the un-limed control and expressed as 

a percentage (Fig.1). At maximum growth (pH 5.6) the growth response to calcite liming 

was similar in both varieties (102 %). However, dolomite liming resulted into higher 

growth response in French bean than in Rosecoco. At liming pH 5.1, 5.6, and 6.8 growth 

increase in calcite and dolomite liming was 112 %, 129 %, 78 % and 86 %, 119 %, 94 % 

respectively. 

110


Uptake of Al 

Al contents in both shoots and roots are presented in Table 3. Both varieties accumulated 

less Al in shoots than in roots. French bean concentrated a higher amount of Al in shoots 

than Rosecoco while Rosecoco accumulated more Al in roots. As liming increased, the 

content of Al in both roots and shoots of both varieties decreased. However the 

concentration of Al in the roots at calcite liming of pH 5.1 contained the highest levels of 

Al, higher than even in the control plants. Generally the Al uptake in the dolomite-limed 

plants contained less Al than in calcite limed ones in both shoots and roots in both 

varieties. 

Uptake of Ca and Mg 

The contents of Ca and Mg in dry shoots and roots in both varieties are presented in 

Table 4. Ca concentration in both shoots and roots of control plants was higher in 

Rosecoco than in French bean. The calcite-limed plants had the highest Ca concentration 

in both shoots and roots at pH 5.6 while dolomite limed plants had their peak at pH 6.8. 

The Ca concentration in both shoots and roots in the calcite and dolomite-limed plants 

was higher in Rosecoco than in French bean. Mg accumulation in shoots of control plants 

was also higher in Rosecoco than in French bean. It increased with liming with calcite to 

reach a peak at pH 5.6. In the dolomite-limed plants, Mg increased with liming to reach a 

peak at pH 6.8. Mg accumulation in the roots of control plants was higher in Rosecoco 

than in French bean. In calcite limed plants the Mg accumulation in the roots increased 

with increasing liming to reach a peak at pH 6.8 in both varieties. Mg accumulation in the 

roots was higher in Rosecoco than in French bean for both types of limes. 

The Ca concentration in both shoots and roots was higher in calcite-limed plants 

than in dolomite limed ones. Mg accumulation in both shoots and roots of the dolomitelimed 

plants was much higher than in calcite treatments. The control plants showed clear 

deficiency symptoms of Ca deficiency, among others were severe stunted growth; 

crinkled, curled leaves and abnormally green first leaves; and some patchy interveinal 

chlorosis in the middle leaves. In the plants limed with calcite to pH 6.8, symptoms of 

Mg deficiency mainly interveinal chlorosis occurred in older leaves, while those treated 

at same pH level with dolomite were normal. 

111


Variety and 

Liming level 

(pH) 

Shoot dry weight 

(g) 

R 3.95 0.4142 ± .027 c 1 

Calcite Dolomite 

Root dry weight 

(g) 

0.1713 ± 0.023 b 

1 Means within columns ( plus/minus one standard deviation) with similar letters do not differ 

significantly (p < 0.05) by Duncan’s multiple range test (n = 4) 

** , *** Significantly different at p = 0.01 and 0.001 respectively 

Table 2: The effect of liming with either calcite or dolomite on the growth of two Phaseolus 

vulgaries varieties, Rosecoco (R) and French bean cv. Amy (F). 


Liming pH 

3.95 5.1 5.6 6.8 3.95 5.1 5.6 6.8 

Rosecoco 

Shoot 0.45 0.36 0.29 0.24 0.46 0.36 0.18 0.17 

Root 

French bean 

6.1 12.0 8.8 6.6 6.1 6.1 2.9 2.5 

Shoot 0.82 0.45 0.3 0.29 0.82 0.29 0.19 0.17 

Root 3.9 5.8 5.0 3.6 3.9 3.2 2.95 2.5 

Table 3 : Uptake of aluminium (mg/g) in dry matter of shoots and roots of Rosecoco and French 

bean in response to liming with either calcite or dolomite 

112 

Shoot dry weight 

(g) 

Root dry weight 

(g) 

0.4142 ± 0.027de 0.1713 ± 0.023 c 

R 5.1 0.6854 ± 0.043 b 0.2222 ± 0.017 a 0.855 ± 0.021 b 0.2433 ± 0.029 b 

R 5.6 0.9011 ± 0.041 a 0.2817 ± 0.0021 a 0.995 ± 0.052 a 0.2967 ± 0.012 a 

R 6.8 0.6185 ± 0.14 b 0.2583 ± 0.0164a 0.9133 ± 0.025 b 0.225 ± 0.0071 b 

F 3.95 0.1917± 0.016 e 

0.0783 ± 0.0153 d 0.1917 ± 0.016 e 0.0783 ± 0.0153 e 

F 5.1 0.3733 ± 0.038 c 0.095 ± 0.00 d 0.4325 ± 0.062 e 

0.1405 ± 0.0076 d 

F 5.6 0.4433 ± 0.034 c 0.1033 ± 0.0153 d 0.4583 ± 0.04 d 0.159 ± 0.025 cd 

F 6.8 0.2867± 0.0058 d 0.0783 ± 0.0153 e 0.3925 ± 0.0035 e 0.0875 ± 0.035 e 

Significance 2 

Liming *** *** *** *** 

Variety *** ** *** *** 

Liming x variety ** *** ** ***


DISCUSSION 

The humic Nitisol [3] for which the experiment was conducted is strongly acid with very 

low nutrient content. Therefore the problem of this acid soil is not only the hazards 

associated with acidity like high Al but also quite low levels of P, Ca and Mg. Liming 

soil has the primary objective of raising the pH in order to decrease the soluble amounts 

of Al, Mn and Fe which not only may cause toxicity to plants but also immobilise P. The 

solubility of Mn and Fe is more controlled by soil redox than by pH and therefore in well 

drained soils like in Kenya Highlands where acid soils dominate, Al toxicity and soil 

infertility are the main hindrance to crop cultivation. 

In this study phosphorus and nitrogen were supplied to the plant through 

diammonium phosphate fertilizer as is the custom in the small-scale cultivation of beans. 

The higher growth exhibited in limed plants as compared with control plants is an 

indication of detoxification of Al and increased Ca, and, Mg and Ca nutrition in calcite 

and dolomite limed plants respectively. These soils are low in both Ca and Mg and 

therefore a liming material like dolomite, which contains both of the elements, is bound 

to increase more the yield of crops than calcite, which contains only Ca. 

The differences in acidity tolerance of the two bean varieties fits fairly well with 

the results earlier obtained [12] where root elongation in three day - old seedlings of 

Rosecoco and French bean was depressed by 38 % and 78 % respectively in nutrient 

solution containing 5 mM Al. Earlier work [10] showed that Al-sensitive plants respond 

more to decreased Al than Al-tolerant ones. The results of this study more or less agree 

with this principle (Fig. 1). The reason is that growth stimulation of root growth upon 

liming is more pronounced in Al – sensitive plants than Al-tolerant ones. However the 

depression of growth upon over-liming in French bean was greater than in Rosecoco. 

Under excessive calcite liming, Rosecoco was probably able to take up more Mg from 

the soil because of its more developed root system while under dolomite liming it was 

able to take up more elements including trace elements, which might have been 

unavailable due to immobilization (high pH) or competition by Ca and Mg. The higher 

response to liming with dolomite than with calcite is easily explained by the presence of 

Mg in the former because of the low Mg content in the test soil. The higher response to 

liming by French bean was not correlated with either Ca and Mg concentration and this 

may probably be Al toxicity was more critical than Ca or Mg nutrition in this particular 

soil. Barley grown in hydroponics had roots with higher contents of Al than in shoots [4]. 

This is in conformity with the results in this work (Table 3). 

In control plants the shoots of Rosecoco contained less Al than the Al-sensitive 

French bean. Therefore the sensitivity of French bean to Al may be its inability to 

exclude Al to roots but also to the tops. There is therefore a need to also study the toxicity 

effects of Al in tops, which has hitherto been neglected. However roots of Rosecoco 

contained more Al in roots than those of French bean. If tolerance were achieved by Al 

immobilization in the cell wall, a reduction in membrane transport would be balanced by 

increase binding of Al in the apoplasm [15]. Thus, Al tolerant plants may have more or 

less Al as Al-sensitive ones. However this contradicted earlier results [12] where 3 dayold 

seedlings of Rosecoco had less Al in roots. Probably the accumulation of Al in cell 

wall through binding to cell walls after apoplasm immobilization increases with age of 

113


the plants. In this earlier work, Rosecoco’s tolerance was mainly due to Al 

immobilization by citric acid excreted by roots. 

The Al concentration in both varieties and in both types of liming declined as 

liming was increased. This is expected because as pH is increased the toxic monomeric 

species of Al also decreased. However concentration of Al in calcite treatment of pH 5.1 

is higher than that in controls in the roots of all varieties. This may be explained by the 

very poor growth in the controls, which reduces the uptake of all elements including Al. 

Liming 

pH 

Rosecoco 

Shoot 


3.95 5.1 5.6 6.8 3.95 5.1 5.6 6.8 

Ca 2.7 16.2 24.2 18.7 2.7 11.8 14.4 18.5 

Mg 1.1 1.2 1.4 1.2 1.1 4.9 6.0 7.5 

Root 

Ca 2.2 7.8 17.1 18.5 2.2 7.4 8.8 9.3 

Mg 0.9 1.6 2.4 3.3 0.9 5.3 8.5 11.1 

French 

bean 

Shoot 

Ca 2.7 18.7 19.3 18.8 2.7 8.8 11.0 15.5 

Mg 1.0 1.2 1.7 1.7 1.0 5.1 5.7 6.9 

Root 

Ca 1.3 4.3 8.7 10.3 1.3 4.0 7.5 8.3 

Mg 0.8 1.2 2.5 2.2 0.8 3.0 5.6 5.9 

Table 4 : Uptake of Ca and Mg (mg/g) by the dry shoots and roots of Rosecoco (R) and French 

bean (F) upon liming with either calcite or dolomite 

The lower concentration of Al in dolomite treated plants implies that Mg just like Ca has 

Al-toxicity ameliorating role [9]. 

114


Many studies have shown the role played by Ca in reduction of Al toxicity in 

plants. Al reduced Ca uptake in Al-sensitive wheat cultivars [9] while Al-tolerant Dade 

Snap bean cultivar contained more Ca in its exudate than that of Al-sensitive Romano 

cultivar [5]. Higher Ca concentrations in nutrient solution decreased Al-tolerance 

differences among maize inbred lines [13]. In this study (Table 4), the Ca in shoots 

agrees very well with other work [6] where the tolerant Dayton barley cultivar 

accumulated more Ca than the Al-sensitive Kearney when Al was added into the nutrient 

solution. In this study the Rosecoco plants had a higher Ca concentration than French 

bean irrespective of liming level and type, indicating its higher capacity to take Ca due to 

its better root development even at acid soil conditions. 

The peak Ca uptake was arrived at pH 5.6 in calcite limed plants and at pH 6.8 in 

dolomite limed ones. The reason may be that in calcite limed plants Mg deficiency 

reduces growth so much at pH 6.8 as reduce Ca uptake. The content of Ca in shoots of 

control plants is less than 1.5% the minimum for optimal growth [7] and this explains the 

Ca deficiency symptoms mentioned earlier. 

The Mg concentration in shoots was higher in the more Al- tolerant Rosecoco than 

in the French bean in both calcite limed probably due to its better-developed root system 

even in very acid conditions. 

The Mg concentration rises with liming in the shoots and roots of calcite limed 

plants to reach a peak at liming pH 5.6; declining at pH 6.8 due to reduced growth 

associated with Mg deficiency. In dolomite limed plants, the peak is reached at liming pH 

6.8. This may be due to factors associated with over liming like trace element deficiency 

though no deficiency symptoms were observed. 

The content of Mg in control plants and in all calcite limed plants is less than 0.5% 

of dry weight which is necessary for optimal growth [11], thus the cause of the Mg 

deficiency symptoms mentioned above. 

CONCLUSIONS 

The study has conclusively shown the beneficial benefits of liming a low fertility, acid 

soil. Dolomite liming gave better growth than calcite and therefore the former should 

berecommeded as the type of liming material for acid soils of the tea zones of Kenya. 

The increase in the dry weight of the whole plant is well related to Al – tolerance; the 

more the response to dolomite liming the more sensitive the bean variety. 

Al accumulation in the shoots of un-limed plants is a good indicator of acidity 

tolerance just like in young plants [12] but not so for Al in roots which seem to 

accumulate more in Al tolerant Phaseolus vulgaries. Al accumulation in roots of 

Phaseolus vulgaries grown in soil to near maturity gives contradictory result to that 

found in young plants and therefore use of Al contents in screening plants in soil grown 

to near maturity can only be done in combination with other techniques. Both Ca and Mg 

accumulation can be used to assess Al-tolerance in the common bean (Phaseolus 

vulgaris) grown in soil. 

The most ideal liming pH level for maximum growth is 5.6 in this strongly acid soil 

irrespective of the liming material. 

115



The authors wish to thank the Japanese Co-operation Agency (JICA) for funding this 

study, and also the Jomo Kenyatta University of Agriculture and Technology for the 

provision of laboratory facilities. 

REFERENCES 

[1] M. M. Alley, L.W. Zelazny. “Soil acidity: Soil pH and lime needs. In Soil Testing: Sampling, 

Correlation, Calibration and Interpretation”, Ed. J.R Brown. pp.65-72. Soil science Society of America, 

Madison, Wisconsin, U.S.A, (1987). 

[2] H. D. Chapman, P. F. Platt. Methods of Analysis for Plants, Soils and Waters. Univ. California. 309 p., 

(1961) 

[3] FAO - UNESCO. Soil map of the world, Rome, (1988). 

[4] C. D. Foy, A.L. Fleming, W.H. Arminger, “Characterization of differential Al tolerance amongst 

varieties of wheat and barley”, Soil Sci. Soc. Am. Proc., 31, 513 -521, (1967). 

[5] C. D. Foy, A. L. Fleming, G. Gerloff. “Differential aluminium tolerance of soybean varieties”, Agro. J. 

64: 815 -18, (1972). 

[6] C. D. Foy, A. L. Fleming, J.W. Schwartz. “Opposite and aluminium and manganese tolerance in two 

wheat varieties”, Agro. J. 65: 123-26, (1973). 

[7] A. D. M. Glass. Plant nutrition-An Introduction to Current Concepts, Jones and Bartlet Publishers, inc. 

234 p. (1989). 

[8] G. Hinga, F. N. Muchena, C. M. Njihia. Physical and Chemical Methods of Soil Analysis, NAL-MoA, 

Kenya. (1980). 

[9] J. W. Huang, J.E. Shaff, D.L. Grunes, L.V. Kochian.. “Aluminium effects on calcium fluxes at the root 

apex of aluminium-sensitive wheat cultivars”, Plant Physiol., 98: 230-37, (1992b) 

[10] J. F. Ma, S. J. Zheng, X. F. Li, K. Takenda, H. Matsumoto. “A rapid hydroponic screening for 

aluminium tolerance in barley”, Plant and Soil. 191: 133-37, (1997a). 

[11] H. Marschner. Mineral Nutrition of higher plants, Inst. of plants Nutrition.Univ. Hohenheim, 

Germany. 889p., (1986). 

[12] E. N. Mugai, S. G Agong, H. Matsumoto. “Aluminium tolerance mechanisms in Phaeolus vulgaris 

L.: Citrate synthase activity and TTC reduction are well correlated with citrate secretion”, Soil Sci. Plant 

Nutr., 46, 939-950, (2000). 

[13] R. D. Rhue, C. O. Grogan. “Screening corn for aluminium tolerance”. Agron. J. 69,755 - 760, (1977). 

[14] W. G. Sombroek, H. M. H. Braun, B. J. A. van der Pouw. Exploratory Soil map 

and Agro-Climatic Zone Map of Kenya. Kenya Soil Survey. MoA. (1980) 

[15] G. J. Taylor. “Current views of the aluminium stress response; the physiological basis of tolerance”. 

Curr. Top. Plant Biochem. Physiol., 10, 57-93, (1991). 

[16] S.M Wokabi. “The distribution, characterization and some management aspects of acid soils of 

Kenya”, Paper presented at IBSRAM’S 2 nd Regional Workshop in Land Development, Lusaka, Zambia. 

Kenya Soil Survey, (1987). 

116


EFFECT OF P FERTILISERS AND WEED CONTROL 

ON THE FATE OF P FERTILISERS APPLIED TO SOILS 

UNDER SECOND-ROTATION PINUS RADIATA 

A. A. Rivaie 1 , P. Loganathan 2 , and R. W. Tillman 2 

1 Indonesian Center for Estate Crops R & D, Jl. Tentara Pelajar No.1, Bogor, Indonesia 

(arivinrivaie@yahoo.com). Telp/Fax: 62 0251 336194; 2 Soil Science, Massey University, Private Bag 

11222, Palmerston North, New Zealand (P.Loganathan@massey.ac.nz; R.Tillman@massey.ac.nz) 


Phosphorus is an important nutrient in New Zealand forest plantations as most of the soils 

are P deficient or marginally deficient, and this element has been routinely applied since 

the 1960’s where appropriate. However, most of the information available on the P 

fertiliser requirements of radiata pine was obtained from trials on first-rotation forests 

that were managed under silvicultural regimes which were quite different from today. 

The current silvicultural regimes of Pinus radiata plantations with wider initial tree 

spacings have created the potential for increased growth of understorey vegetation. A 

consequence of this is that the response of P. radiata to P fertiliser is expected to be more 

influenced by the interaction between the P fertiliser, the tree and the understorey 

vegetation than was the case in the past. 

The objectives of this study were to determine the effect of application of different 

rates of two P fertilisers (Triple superphosphate (TSP) and Ben Guerir phosphate rock 

(BGPR)) and weed control, and their interactions on P fractions and downward 

movement of P, in an Allophanic Soil (at the Kaweka forest) and a Pumice Soil (at the 

Kinleith forest) under 4-5-year-old second-rotation P. radiata plantations. 

The results showed that P fraction containing the largest percentage of soil P was 

the 0.1 M NaOH extractable Po, in the surface soils (0-10 cm soil depth) at the two 

second-rotation forests. In the Allophanic Soil, NaOH-Po concentration was 196 µg P g -1 

soil, which was 41% of the total P, and in the Pumice Soil it was 253 µg P g -1 soil which 

was 64% of total P. Therefore, the long-term P supplying power of the soil largely 

depends on the mineralisation of this organic P. 

The NaOH-Pi and the H2SO4-Pi concentrations in the soils had increased at both 

forests two years after P fertiliser application, whereas, the largest pool of P, NaOH-Po, 

and residual-P were unaffected by the P fertiliser application. Changes in the 

concentration of P fraction as a result of P fertiliser application depend on the P fertiliser 

type. When increased rates of TSP were applied, the NaOH-Pi fraction (averaged over 

weed and weed-free treatments) increased at a faster rate than the other P fractions and 

the rate of increase was more marked at the Kaweka forest (an Allophanic Soil) than at 

the Kinleith forest (a Pumice Soil). This suggested that the proportion of TSP applied to 

the soil that was adsorbed to allophane and Fe+Al oxides was more than that converted to 

any of the other P fractions. The higher rate of increase of NaOH-Pi concentrations at the 

Kaweka forest than at the Kinleith forest is probably due to the higher P fixation capacity 

of the Kaweka soil compared to that of the Kinleith soil. 

117


When increased rates of BGPR were added, the H2SO4-Pi fraction (averaged over 

weed and weed-free treatments) increased at a faster rate compared with the other P 

fractions and the rate of increase was also more marked at the Kaweka forest than at the 

Kinleith forest. This is due to the high concentration of undissolved PR (P associated 

with Ca) remaining in the soils, which was extracted by H2SO4. In comparison, the 

addition of TSP increased the H2SO4-Pi concentrations only at 100 and 200 kg P ha -1 in 

the Kaweka soil and at 200 kg P ha -1 in the Kinleith soil. While, the increase in H2SO4-Pi 

concentrations resulting from the increase in BGPR rates of application is due to an 

increase in concentration of undissolved PR, the increase in H2SO4-Pi with an increase in 

TSP rates is due to the increase in concentrations of dicalcium phosphate resulting from 

the conversion of MCP in TSP to dicalcium phosphate. 

In general, the magnitude of the increase in H2SO4-Pi concentrations per unit weight 

of BGPR addition at the Kaweka forest was greater than that at the Kinleith forest. This 

may be due to the higher rate of dissolution of BGPR in the Kinleith soil than in the 

Kaweka soil, as the former was more acidic than the latter (pH 5.1 and pH 5.7, 

respectively). The supply of H + is a driving force for the dissolution of PR, along with the 

removal of the dissolution reaction products Ca 2+ , H2PO4 - and F - from the site of 

dissolution. 

Rainfall at the Kinleith forest during the trial period was higher than at the Kaweka 

forest (annual rainfall for 2001 at Kinleith was 1491 mm and at Kaweka was 1285 mm; 

for 2002 they were 1702 and 1280 mm, respectively). It is possible that this would have 

resulted in a higher soil moisture regime at the Kinleith forest to help further the 

dissolution of BGPR. But the Kaweka soil had lower exchangeable Ca and resin-Pi 

concentrations and higher P fixing capacity compared to the Kinleith soil, therefore, 

based on these properties PR dissolution would have been expected to be higher at 

Kaweka soil. The fact that the observed dissolution was lower in the Kaweka soil 

indicates that the effect of the higher acidity and moisture content in the Kinleith soil 

overrides the influences of P fixing capacity, P concentration and exchangeable Ca in the 

soils in promoting a higher rate of BGPR dissolution in the Kinleith soil. 

The effect of weeds on plant-available soil P concentration (resin-Pi) depends on 

the type of weeds and the degree of P deficiency in the soil. The deeper root systems of 

the weeds (Himalayan honeysuckle, buddleia and some toetoe) at the Kinleith forest 

enhanced the plant-available P concentrations in soil surface probably by removing P 

from the subsoils and returning it in the form of litter to the soil surface (pumping 

mechanism). At the P-deficient Kaweka forest soils, however, the weeds (bracken fern 

and manuka) reduced resin-Pi concentration. This suggests that when plant-available P is 

very low, the weeds tend to compete with radiata for P. 

At both forests, the application of 200 kg P ha -1 as TSP and BGPR increased Bray- 

2 P at the 0-10 cm soil depth. At the 10-20 cm soil depth, however, the application of any 

of the two P fertilisers at the rate of 200 kg P ha -1 had no effect on Bray-2 P concentration 

at the Kaweka forest, while at the Kinleith forest the two P fertilisers increased Bray-2 P 

concentration. There was no fertiliser effect on Bray-2 P concentration at the 20-30 cm 

soil depth at both sites. This suggested that in the Pumice Soil at the Kinleith forest, P 

from both TSP and BGPR has leached to the lower depth. In the less porous and higher P 

fixing Allophanic Soil at the Kaweka forest it might have been difficult for the fertiliser P 

118


to have moved to below 10 cm depth. The movement of P in Kinleith forest was higher 

for TSP than BGPR because of higher solubility of TSP. 

119


Sub-theme : ORGANIC FARMING IN THE TROPICS 

PRESENT SITUATION, POSSIBILITIES AND CHALLENGES 

Current research at the research group of soil fertility and nutrient management 

Stefaan De Neve 

Department of Soil Management and Soil Care, University of Gent, Gent, Belgium 

The research group on Soil Fertility and Nutrient Management is part of the department 

of Soil Management and Soil Care, which does research on all aspects of applied soil 

science, including soil fertility, soil organic matter, soil physics, soil erosion and soil 

conservation, soil pollution and its remediation, and soil data processing. 

The research focus in the Soil Fertility and Nutrient Management group has 

gradually shifted from soil fertility related to maximising plant production towards 

environmental aspects related to fertilization and soil organic matter management. The 

main focus of the department is at present on the cycles of carbon and nitrogen in soil, 

and is reflected in a number of research topics that are briefly outlined below. 

Fundamental research is going on about soil organic carbon (SOC) along different 

lines. A first line is the determination in soil of a passive SOC pool, i.e. a SOC pool that 

is by definition not affected by management but remains constant in size over centuries. 

This research uses a combination of physical fractionation methods (size and density 

fractionation) and chemical fractionation, in order to isolate silt and clay associated SOC 

and further subdivide this in biochemically and non-biochemically resistant SOC. The 

fractionations are combined with advanced mass spectrometrical analyses. 

A second line is the visualization of physically protected SOC within microaggregates 

and the relationship between soil micro-architecture and SOC partitioning 

using X-ray computed nano tomography. This research should help to improve our 

understanding of mechanisms of physical protection of SOC, including the improvement 

of existing SOC models. 

With regard to nitrogen, a more fundamental line of research is about the 

dynamics of dissolved organic nitrogen (DON) in forest soils in Flanders. Over the last 

decades, research on DON has received increasing attention as a possible important loss 

mechanism for N and as a biologically active component in the N cycle. We are looking 

at the importance of DON losses in forest soils in comparison to overall N leaching 

losses, and will try to model DON dynamics in these soils, based on laboratory 

measurements of the mineralization, sorption and desorption, chemical composition and 

transport in the vadose zone. 

Another research line is the interaction between exogenous organic matter (EOM) 

that is applied to agricultural soil, the soil structure and soil physical properties, and soil 

foodweb dynamics, and how this interaction influences C and N cycling in soil. To this 

end, a field experiment was started where different qualities of EOM are applied in 

controlled quantities and where we monitor changes in soil physical properties/soil 

structure, changes in foodweb dynamics (notably microfauna, nematodes and 

earthworms) and associated C and N dynamics. 

120


Applied lines of research included research on alternative agricultural production 

systems such as reduced tillage agriculture/conservation agriculture and organic farming. 

Our research on reduced tillage is focussed on how this type of agriculture influences soil 

structure and soil physical properties, crop yields, and C and N dynamics from soil 

organic matter (SOM), including C storage, C and N mineralization, N2O emissions, 

nitrate leaching and overall nitrogen use efficiency. Research is also going on about the 

dynamics of crop residues under reduced tillage agriculture, namely C and N 

mineralization, NH3 and N2O emission and soil quality parameters including enzyme 

activities, microbial biomass, earthworms, … The organic farming systems research in 

our department until now has focussed on nutrient use efficiency compared to 

conventional agriculture, with emphasis on nitrate leaching losses and phosphorus 

saturation. An important part of the research is focussed on field grown vegetable crops, 

because in that particular sector many problems of over-fertilization and excessive 

nutrient losses are concentrated. 

Finally, we are conducting research on nutrient balances and nutrient efficiencies 

of all kinds of organic manures and wastes to provide scientific support for new 

legislation concerning nutrient management in Flanders and in Europe. 

REFERENCES 

[1] Coleman D, Fu SL, Hendrix P & Crossley D. 2002. Soil foodwebs in agroecosystems: impacts of 

herbivory and tillage management. European Journal of Soil Biology 38, 21-28. 

[2] De Neve S., Pannier J. and Hofman G. 1996. Temperature effects on C and N mineralization from 

vegetable crop residues. Plant and Soil, 181, 25-30. 

[3] Ferris H, Bongers T, de Goede RGM 2001. A framework for soil food web diagnostics: extension of 

the nematode faunal analysis concept. Applied Soil Ecology 18, 13-29. 

[4] D’Haene K., Moreels, E., De Neve S., Chaves Daguilar B., Boeckx P., Hofman G., Van Cleemput O. 

2003. Soil properties influencing the denitrification potential of Flemish agricultural soils. Biology and 

Fertility of Soils, 38, 358-366. 

[5] Karlen, D.L., Mausbach, M.J., Doran, J.W., Cline, R.G., Harris, R.F. & Schuman, G.E. (1997). Soil 

quality: a concept, definition and framework for evaluation. Soil Science Society of America Journal, 61, 4- 

10. 

[6] Lenz R & Eisenbeis G. 2000. Short-term effects of different tillage in a sustainable farming system on 

nematode community structure. Biology and Fertility of Soils 31, 237-244. 

[7] Nunan N, Ritz K, Rivers M, Feeney DS, Young IM 2006. Investigating microbial micro-habitat 

structure using X-ray computed tomography. Geoderma 133, 398-407. 

[8] Schulten HR & Leinweber P (2000) New insights into organic-mineral particles: composition, 

properties and models of molecular structure. Biology and Fertility of Soils, 30, 399-432. 

[9] Six J, Conant RT, Paul EA, Paustian K 2002. Stabilization mechanisms of soil organic matter: 

Implications for C-saturation of soils. Plant and Soil 241, 155-176. 

[10] Sleutel S, De Neve S, Singier B, Hofman G 2006. Organic C levels in intensively managed arable soils 

- long-term regional trends and characterization of fractions. Soil Use and Management 22, 188-196. 

[11] Sleutel S., De Neve S., Hofman G., Boeckx P., Beheydt D., Van Cleemput O., Mestdagh I., Lootens 

P., Carlier L., Van Camp N., Verbeeck H., Van De Walle I., Samson R., Lust N. & Lemeur R. 2003. 

Carbon stock changes and carbon sequestration potential of Flemish cropland soils. Global Change 

Biology, 9, 1193-1203. 

[12] Van Den Bossche A., De Neve S. & Hofman G. 2005. Soil phosphorus status of organic farming in 

Flanders: an overview and a comparison with the conventional situation. Soil Use and Management, 21, 

415-421. 

[13] Young IM, Crawford JW 2005. Interactions and self-organization in the soil-microbe complex. Science 

304, 1634-1637. 

121


[14] Zelles L 1999. Fatty acid patterns of phospholipids and lipopolysaccharides in the characterisation of 

microbial communities in soil: a review. Biology and Fertility of Soils 29, 111-129. 

122


LOW INPUT APPROACHES FOR SOIL FERTILITY 

MANAGEMENT VERIFIED FOR SEMI-ARID AREAS OF 

EASTERN UGANDA 

Kayuki C.Kaizzi 1 , Byalebeka John 1 , Charles S. Wortmann 2 and Martha Mamo 2 

1 Kawanda Agricultural Research Institute (KARI), National Agricultural Research Organization (NARO), 

Box 7065 Kampala, Uganda; kckaizzi@hotmail.com, 2 University of Nebraska Lincoln, IANR, Department 

of Agronomy and Horticulture, 154 Keim Hall, Lincoln, NE 68583-0915; cwortmann@unlnotes.unl.edu 

Abstract 

Grain sorghum [Sorghum bicolor (L.) Moenich] is an important food crop in the semi-arid areas of Sub- 

Saharan Africa. Crop yields are generally low and declining partly due to low soil fertility. In an attempt to 

address the problem, 148 on-farm trials were conducted at three sites over three years in the drought prone 

parts of eastern Uganda. The aim of this research was to evaluate, with farmer participation, alternative 

low-input strategies for soil fertility improvement in sorghum based cropping systems. The strategies were: 

use of herbaceous legume (Mucuna pruriens) in improved fallow; a grain legume (Vigna unguiculata) in 

rotation with sorghum; use of cattle manure; application of low levels of N and P fertilizers. Mucuna 

(Mucuna pruriens) on average produced 7 t ha -1 of above ground dry matter containing 160 kg N ha -1 

across the three sites. There was an increase in sorghum grain yield in response to the alternative strategies. 

Application of 2.5 t ha -1 of kraal manure and the application of 30 kg N plus 10 kg P ha -1 both increased 

grain yield by a mean of 1.15 t ha -1 . A combination of 2.5 t ha -1 manure with 30 kg N ha -1 increased grain 

yield by 1.40 tha -1 above the farmer practice (1.1 t ha -1 grain). The increase in sorghum grain yields in 

response to 30 kg N ha -1 alone, to a mucuna fallow, and to a rotation with cowpea (Vigna unguiculata) was 

1.0, 1.4 and 0.7 t ha -1 , respectively. These alternative strategies were found to be cost-effective in 

increasing sorghum yield in the predominantly smallholder agriculture where inorganic fertilizer is not 

used. On-farm profitability and food security for sorghum production systems can be improved by use of 

inorganic fertilizers, manure, mucuna fallow, and sorghum-cowpea rotation. 

Key words: cowpea, low input, Mucuna pruriens, opportunity cost, resource poor, semi-arid, smallholder 

agriculture 

INTRODUCTION 

Grain sorghum is an important crop for smallholder farmers in the drier areas of sub- 

Saharan Africa (SSA) but crop yields are low, and declining in some places [10, 22]. Low 

inherent soil N and P availability are major constraints [1] that are exacerbated by soil 

fertility depletion through nutrient removal in harvest and losses with runoff and soil 

erosion [21,30]. Many farmers are unable to compensate for these losses, resulting in 

negative nutrient balances at the national level for sub-Saharan Africa countries [26] and 

at the farm level in Eastern and Central Uganda [34] 

Nutrient availability can be improved through application of inorganic or organic 

nutrient sources. The profitability of fertilizer use depends on agro-climatic and economic 

conditions at local and regional levels [31]. Infra structural and other marketing constraints, 

lack of agricultural subsidies, and high opportunity costs on available money makes the use 

of inorganic fertilizers very costly in SSA, and real costs to farmers are two to six times as 

123


much as in Europe [20]. Resource-poor farmers need large returns on the small investments 

that they can make, often require a 75% return within a six to 12 month period to make an 

investment competitive [32] 

Use of organic nutrient sources is constrained by labor availability for collecting and 

applying the materials [19], limited quantities and variation in quality [17], and the demand 

for crop residues as fuel and fodder [16] Green manure production requires land that could 

often be used for food or cash crops [6]. Farmyard manure is available to many smallholder 

farmers but generally in small quantities [15]. Transfer of plant materials from field 

boundary areas, or near-by fallow or grazing areas, often has potential in sub-humid areas 

but less potential in semi-arid areas [14,32]. 

Biological nitrogen fixation (BNF) may contribute much N through better 

integration of legumes in farming systems. Biologically fixed atmospheric nitrogen 

contributes to productivity both directly, when the fixed N is harvested in protein of grain 

or other food for human or animal consumption, or indirectly by adding N to the soil for 

the maintenance or enhancement of soil fertility [8]. Under favorable environmental 

conditions, BNF can meet the N requirements of tropical agriculture [6,7,18]. Economic 

constraints make BNF an attractive N source for resource-poor farmers in sub-Saharan 

Africa [9,28]. 

Several promising low input approaches to soil fertility management for sorghum 

production in the drought-prone areas of eastern Uganda were evaluated to verify and 

fine-tune them for the production systems in four related studies. The objectives of these 

studies were to determine sorghum grain yield response to application of inorganic and 

organic N and P sources, mucuna fallow, and cowpea rotation. 

Site characteristics 


Farmer-managed trials were conducted at Kadesok and Opwatetta parishes 

(approximately 33 45’ E and 1 12’N) in the Southern and Eastern Lake Kyoga Basin of 

eastern Uganda and Kapolin parish in the Usuk Sandy Farm-Grasslands (34 0’ E and 1 

40’N) [33]. The altitude ranges from 1050 to 1150 m asl. The trials were part of a larger 

process of participatory research with these communities that began with participatory 

exercises in farming system characterization and diagnosis, identification of potential 

solutions to soil fertility problems, and development of research plans. The process lead 

to farmer participation in the dissemination of research results to other farmers. 

The rainfall at the research sites allows for two cropping seasons per year with an 

annual mean of approximately 1150 mm for Kadesok and Opwatetta and 1000 mm for 

Kapolin. About 25-30% of the rainfall falls outside the crop seasons and is used by 

naturally growing annual or perennial vegetation and unavailable to the planted crops. 

Soil samples for the 0- to 20-cm depth were collected for each trial site, air-dried, ground 

to pass through a 2-mm sieve, and analyzed according to [6]. Extractable P, K and Ca 

were measured in a single ammonium lactate/acetic acid extract buffered at pH 3.8. Soil 

pH was measured using a soil to water ratio of 1:2.5. Soil organic matter was determined 

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according to the Walkley – Black method, modified according to [5]. The dominant soil 

types in the area are petric plinthosols [3]. 

Sets of trials 

Two sets of trials were conducted. Each farm was a replication to minimize the 

probability of Type I error in extrapolating results throughout eastern Uganda. The plot 

size was 100 m 2 for all trials. 

Trial 1 

Use of the herbaceous legume (Mucuna pruriens), in improved fallow and cowpea 

(Vigna unguiculata) in rotation with sorghum were evaluated on 39 farms. The 

treatments were: continuous sorghum; sorghum following cowpea which was produced 

during the August to November short rains; continuous sorghum with 30 kg N ha -1 

applied to the second sorghum crop; and mucuna fallow during the short rains followed 

by sorghum. Sorghum, cowpeas and mucuna were planted in the respective plots during 

the short rains. Sorghum was planted in all plots during the subsequent long rains period. 

No nutrients were applied except for the +N treatment. 

Trial 2 

Sorghum response to applied inorganic fertilizers and manure was evaluated on 64 farms 

during the long rain season. The treatments were: no nutrients applied; 30 kg N ha -1 ; 30 

kg N plus 10 kg P ha -1 ; 2.5 t manure ha -1 ; and 30 kg N plus 2.5 t manure ha -1 . The manure 

was collected from open pens where farmers kept their cattle and goats at night. Cowpea 

was planted on all plots during the previous short rains season. 

Crop management practices, application of manure and inorganic fertilizers 

Manure and P fertilizers were applied at planting. Nitrogen was applied in two splits with 

5 kg N ha -1 at planting and the remaining 25 kg N ha -1 six weeks later. Sorghum (cv. 

“Sekedo” and “Epurpur”) was planted at 60 x 20 cm during the long rains of 2004 

(season 2004A) and 2005 (2005A). Mucuna was planted at a spacing of 75 x 60 cm and 

cowpea at 45 x 20 cm during the short rains of 2003 (2003B) and 2004 (2004B). Inseason 

weed control was with hand hoes. Beta-cyfluthrin was applied 3 to 4 weeks after 

sorghum had germinated to prevent damage by stem borers and chloropyrifos 5% was 

applied for termite control. 

Sorghum and cowpea stover were left in the field. The mucuna that remained after 

biomass measurements continued to grow until the soil water was depleted. Some of the 

mucuna, as well as some of the stover of sorghum and cowpea, was grazed by livestock 

during the dry season as livestock generally graze freely in the fields after harvest of the 

crops. Mucuna seeds remained in the field and germinated during the subsequent long 

rains, the volunteer plants were controlled until the second weeding after which emerging 

mucuna was allowed to grow in competition with the sorghum crop. 

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Data collection and analysis 

Sorghum grain yield was determined by harvesting the whole plot at maturity. The grain 

was weighed after air-drying and threshing. Sub-samples were collected for moisture 

determination and the grain yield was adjusted to 14% water content. 

Mucuna biomass production was determined at 22 weeks after planting by harvesting an 

area equivalent to 3 m 2 using a 1 m 2 quadrant placed randomly at three different places 

within a plot. All the materials within the quadrant including litter were collected and 

weighed. A sub-sample was dried in an oven at 70˚C, ground to pass a 0.5 mm sieve and 

analyzed for total N, P and K by Kjeldahl digestion with concentrated sulphuric acid [1]. 

P was determined calorimetrically, and K by flame photometry. 

Cowpea grain yield was determined at physiological maturity by picking pods only, 

a common practice in the area. Harvested grain was weighed after air-drying. Subsamples 

were collected for moisture determination and the grain yield was adjusted to 

14% water content.Analyses of variance were conducted by site and season for all sets of 

trials using Statistix V. 8.0 [25]. Differences were considered significant at the P ≤ 0.05 

level. 

ECONOMIC ANALYSIS 

The profitability of alternative practices was assessed. The analysis for fertilizer use was 

based on the following assumptions [32]: 

1. Opportunity cost, including risk allowance, was assumed to add 25, 50, and 75% 

to the cost of using fertilizer for the undefined categories of less poor, poor and very poor 

farmers, respectively; 

2. Farm gate crop prices were reduced by 10% to cover the cost of harvesting, 

processing, and marketing; 

3. Fertilizer costs were increased by 10% to cover transport and application costs; 

4. Plot yields were assumed to be high relative to yields that small-scale farmers 

can achieve at a farm-level and were reduced by 10% in the economic analysis. 

5. Prices in Uganda shillings (UgSh 1,800/- = US $1) were assumed to be 200/- and 

300/- kg -1 for sorghum and cowpea, respectively, at the farm-gate, and 40,000/- for 50-kg 

bags of urea and triple super phosphate. 

Soil characteristics 

RESULTS AND DISCUSSIONS 

During the characterization and diagnosis process, farmers named different soils in the 

area and described these for their location on the landscape, associated problems, and 

soil-specific coping mechanisms. The major constraints mentioned by farmers include 

low soil fertility, low water holding capacity for sandy soils, water logging for clayey 

soils, and weeds. Researchers and farmers discussed possible solutions to the problems 

and farmers then agreed to participate in their evaluation. 

126


Soil texture class for the experimental sites ranged from sandy clay loam to sand 

with sand contents of 58 to 92% (Table 1). The pre-dominant texture classes were sandy 

loam and loamy sand, and of low water holding capacity. The soils for most trial sites had 

chemical values below the critical low levels estimated for Uganda soils [5]. Soil organic 

matter varied widely but was often low. Available P was below the critical level in most 

fields. Extractable K and Ca levels were low in 24 – 33% and 10-16% of the fields, 

respectively. Depletion of soil K probably occurred partly due to past harvests of cassava 

and sweet potato. The soil test results were typical for the area [23]. 

Soil property Kadesok Opwatetta Kapolin Critical 

127 

values a 

pH1:2.5 

6.1 (5.4 – 6.6) 6.0 (5.2 – 7.2) 6.1 (5.3 – 7.5) 5.2 

SOM (mg kg -1 ) 28 (19 – 42) 28 (26 – 41) 22 (17 – 35) 30 

Extractable P (mg kg -1 ) 

1.3 (1 – 6) 1.3 (1 – 5) 2.80 (1 – 9) 5.0 

Extractable K (cmolc kg -1 ) 5.1 (2 – 10) 6.2 (3 – 10) 5.4 (2 – 10) 0.4 

Extractable Ca (cmolc kg -1 ) 41 (8 – 45) 36 (5 – 54) 31 (5 – 68) 0.9 

Sand (%) 71 (66 – 88) 76 (58 – 82) 84 (62 – 92) na 

Silt (%) 7 (2.6 – 13) 5 (1.3 – 15) 5. (3 - 11) na 

Clay (%) 2 (6.5 – 27) 19 (14 – 29) 11 (5 – 29) na 

a 

Below these values, soils are deficient or poor [5]; na = not applicable. 

Table 1: The median values and ranges for soil properties for the on-farm trial field 

in three communities 

Trial 1: Sorghum response to improved fallow and rotation with cowpea 

The mean above-ground dry matter production by mucuna across the three sites was 7 t 

ha -1 containing 160 kg N ha -1 , 14 kg P ha -1 , and 94 kg K ha -1 This agrees with other 

findings in the region where mean dry matter production was 7.3 t ha -1 , containing 180 kg 

N ha -1 with 103 kg N ha -1 derived from the atmosphere [11,13]. Farmers usually fallow 

their fields or grow cowpeas rather than sorghum during the short rain season (season B) 

due to the uncertainty of the rains and heavy feeding by birds. The mean cowpea grain 

yield during the short rains was 0.82 t ha -1 , and the mean sorghum grain yield for the few 

farmers who harvested a short-season crop at Opwatetta and Kadesok was 1.05 t ha -1 ; 

these short season yields were used in the economic analysis.


Treatment Kadesok Opwatetta Kapolin 

2004A 2005A 2004A 2004B 2005A 2004A 2005A 

Number of on-farm trials 5 8 5 3 7 6 5 

Previous sorghum 1.03 1.76 1.17 1.00 1.39 0.67 0.96 

Previous cowpea 1.84 3.19 1.61 2.00 2.17 1.43 1.18 

Previous sorghum, 

30 kg N ha -1 

2.30 3.49 1.65 2.50 2.43 2.05 1.36 

Previous mucuna 2.64 3.98 1.76 2.67 3.00 2.81 1.47 

LSD0.05 0.27 0.27 0.29 0.56 0.39 0.53 0.15 

Table 2 : Sorghum grain yield (t ha -1 ) during the long rains of 2004 and 2005 in three 

communities 

All treatments resulted in increased sorghum grain yield at all sites in both years 

relative to continuous sorghum with no fertilizer applied (Table 2). The overall mean 

increase in sorghum grain yield due to the effect of rotation with cowpea as compared to 

continuous sorghum was 0.72 t ha -1 with a range of 0.2 to 1.4 t ha -1 for the means of sites 

and years. The effect of applying 30 kg N ha -1 to sorghum following sorghum was an 

overall mean increase in sorghum yield of 1.03 tha -1 with a range 0.4 to 1.7 t ha -1 . The 

effect of mucuna grown during the previous short rain season was an overall mean 

increase in sorghum yield of 1.43 t ha -1 with a range 0.5 to 2.2 t ha -1 . Thus, inorganic N 

fertilizer, cowpea rotation, and mucuna fallow served as effective N sources for sorghum 

at the three sites. The relatively greater increase in sorghum grain yield due to the 

improved fallow with mucuna is in agreement with results reported for maize 

[3,11,26,28]. The higher mean response for sorghum following mucuna as compared to 

cowpea is expected as a large amount of fixed N was removed in the harvest of cowpea 

grain while most mucuna biomass was left in the field. 

Treatment Gross returns 

(,000 UgSh ha -1 ) 

Previous sorghum 371.2 

Previous cowpea 535.7 

Previous sorghum, 30 kg N ha -1 488.7 (25) b , 474.3 (50), 460.0 (75) 

Previous mucuna c 453.7 

b Values in parenthesis are opportunity costs 

Table 3: The gross returns, excluding fertilizer costs at 25, 50 & 75% opportunity costs, for 

sorghum produced in the long rainy season following either sorghum, cowpea or mucuna 

produced in the short rainy season. 

The most economical cropping system was the cowpea-sorghum rotation followed 

by continuous sorghum with 30 kg N ha -1 fertilizer and the mucuna rotation (Table 3). 

Least profitable was the continuous sorghum without N. However, production costs were 

assumed to be similar for the previous crops while the cost of producing mucuna was 

undoubtedly less than for sorghum and cowpea due to easier planting, weed control and 

no harvest. The value of grazing of the mucuna during the dry season was not estimated 

but was probably greater than the value of grazing sorghum and cowpea stover. Accurate 

128


estimation of the true costs and benefits would improve the estimated profitability for the 

mucuna treatment to the extent that it may be the most profitable practice. 

Trial 2: Sorghum response to application of manure and inorganic fertilizer 

All manure and fertilizer treatments resulted in increased sorghum grain yield at all sites 

in all years relative to the control treatment with no nutrients applied (Table 4). The mean 

increases in sorghum grain yield, across sites and years, due to application of 30 kg N ha - 

1 and 2.5 t ha -1 manure was 1.3 and 1.2 t ha -1 , respectively. Application of 10 kg P ha -1 in 

addition to the 30 kg N ha -1 resulted in a mean additional yield increase of 0.27 t ha -1 with 

site-year mean increases ranging from


Treatment Increase in 

grain yield (t 

ha -1 ) 

Net returns to input use 

(,000 UgSh ha -1 ) a 

130 

Benefit:cost ratio 

25% 50% 75% 25% 50% 75% 

30 kg N + 10 kg P ha -1 1.27 83.3 58.8 34.3 1.68 1.40 1.20 

30 kg N + 2.5 t manure ha - 

1 b 

1.40 54.4 29.9 5.4 1.32 1.15 1.02 

30 kg N ha -1 0.93 78.9 64.6 50.2 2.10 1.75 1.50 

2.5 t manure ha -1 1.02 115.2 115.2 115.2 3.30 3.30 3.30 

Table 5: Increase in sorghum grain yield (t ha -1 ) and net returns and benefit:cost ratios for 

opportunity costs of money of 25, 50, and 75%, averaged across all location/years 

DISCUSSION 

The results presented in Tables 2, 4 and 5 show that sorghum yield is most constrained by 

soil N. However, soil tests results show that the availability of P and other nutrients is 

often low. Crop yield may therefore be limited by deficiency of one or more of these 

nutrients if crop yields are increased due to improved N availability. Application of a 

wide range of nutrients and organic matter with manure may contribute to the 

sustainability of the higher yield levels. The nutrient content of the manure on a dry 

matter basis was in the range 0.7 – 1.8%, 0.1 - 0.2% and 0.8 - 2.4% for N, P and K, 

respectively. The manure was from open pens and a large proportion of the manure N 

was probably in organic rather than ammonium form. Much of the organic N was 

probably not mineralized during the season and may benefit subsequent crops. 

Manure use, however, is a process of transfer of nutrients from one part of the 

farming system to another rather than a replacement of nutrients exported in marketed 

harvest resulting in a negative farm level nutrient balance in the long run. Eventually, 

there will be a need to bring nutrients to the farm to sustain the higher levels of 

productivity and marketing of grain. Also, there is insufficient manure to apply 2.5 t ha -1 

yr -1 to most of the cropland although manure is currently an under-utilized resource. 

Including legumes in the rotation apparently improved N availability. The cowpeasorghum 

rotation resulted in a significant increase in sorghum yield while providing a 

cowpea grain harvest the previous season. Using the short rain season to produce a 

mucuna fallow resulted in the greatest increase in sorghum yield. This is in agreement 

with the results reported for maize in eastern and central Uganda [4,11,12,13]. 

Furthermore, mucuna itself has some economic value as livestock grazed it during the 

dry season when fodder was scarce. Application of N fertilizer resulted in a mean 

sorghum grain yield that was intermediate relative to the yields following the legumes. 

The use of N fertilizer means a cash expense to the farmer but allows more choice in land 

use during the short rain season. The results of the economic analysis show that fertilizer 

use is profitable for all the farmers but less so for the poorest farmers with the greatest 

opportunity cost. 

Several of the practices tested were verified as promising and a strategy is needed 

to achieve widespread adoption. Some of these practices had sufficient effect on crop 

performance that field demonstrations should be very effective if conducted throughout


the semi-arid sorghum production areas of eastern and northern Uganda. Farmer 

involvement in the full research process ensured that the practices are compatible with 

their farming systems. Also, the practices are easily testable by adopting farmers. 

Extension staff working in the target areas need to be enabled to conduct and 

effectively use demonstrations to inform farmers of the benefits of these practices. The 

participating farmers, who were involved from the characterization and diagnosis 

exercises through the implementation of trials and assessment of the results, are a 

potential resource for an organized farmer to farmer dissemination of the information. 

CONCLUSIONS 

Inorganic fertilizers, animal manure, N fertilizer combined with manure, mucuna fallow 

and cowpea rotation enable profitable increases in sorghum yield on the sandy loam and 

loamy sand soils of eastern Uganda. Inadequate N availability is the most limiting 

nutrient in the traditional production systems in this area. Application of a small amount 

of P in inorganic fertilizer or manure, in addition to N, is also profitable at three 

opportunity costs for money. The cowpea-sorghum rotation is a relatively profitable 

cropping system, especially if fertilizer N or manure is applied to the sorghum crop. The 

use of mucuna as a short rain season fallow crop is a promising source of N and organic 

material, as well as dry season fodder, for the resource-poor smallholder farmers of 

eastern Uganda. Available manure needs to be used efficiently as it supplies some of all 

soil nutrients essential to crop growth, some of which are likely to become more limiting 

with increased crop yields. Longer-term on-station research is needed to determine the 

sustainability of these low input approaches to soil fertility management. 


The authors are grateful to the participating farmers and to Mr. Dennis Odelle, Mr. Bazil 

Kadiba, Mr. Patrick Odongo and Mr. William Acoda, the field assistants at the research 

sites. The research was made possible by the National Agricultural Research 

Organization (NARO), the International Sorghum/Millet Collaborative Research Support 

Program (INTSORMIL) and by funding from the U.S. Agency for International 

Development under the terms of Grant No. LAG-G-00-96-900009-00. 

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nitrogen for sustainable agriculture? Plant and Soil, Volume 174, pp. 3-28 (1995). 

132


AMELIORATION OF ACID SULFATE SOIL INFERTILITY IN 

MALAYSIA FOR RICE CULTIVATION 

J. Shamshuddin 

Department of Land Management, Faculty of Agriculture, Universiti Putra Malaysia, 43400 Serdang, 

Selangor Malaysia 

Abstract 

Normally, acid sulfate soils are not suitable for crop production. Unless they are properly ameliorated using 

appropriate technology in agronomic practices, the soils are not put to agriculture production. The objective 

of this study was to ameliorate an acid sulfate soil in Malaysia using dolomitic limestone (GML) and an 

organic-based fertilizer for rice cultivation. The soils at the experimental plots belong to the Nipis-Bakri 

Associations (organic soils underlain by sulfidic materials with 50 cm depth), which can be classified as 

Typic Sulfosaprists. The rice (Oryza sativa) variety used in the trial was MR 219. The treatment included a 

control (T1, no lime), 2 t GML/ha (T2), 4 t GML/ha (T3), 6 t GML/ha (T4), 8 t GML/ha (T5), 4 t GML/ha 

+ organic fertilizer (T6) and 4 t GML/ha + fused magnesium phosphate (T7). The result showed that the 

initial topsoil pH was low. At the depth of 45-60 cm, the pH values were lower than 3.5. The initial topsoil 

exchangeable Ca ranged from 1.17 to 1.68 cmolc/kg soil, lower than the required level for rice of 2 

cmolc/kg soil. The initial exchangeable Mg was only 0.50-0.53, but Mg requirement is 1 cmolc/kg soil. The 

highest rice yield for the 2 nd season was 7.5 t/ha obtained by T6. For this treatment, 4 t GML/ha were 

applied in combination with the organic fertilizer. This yield is comparable to the yield of rice grown on 

good soils in the granary areas of the west coast of the Peninsular Malaysia. The national average for 

Malaysia is 3.8 t/ha. It was observed that the yield obtained by T6 was not significantly different from that 

of T3, T4 and T5. This trial showed that applying 2 t GML/ha (T2) is not enough to ameliorate these soils 

for rice cultivation. For the T2, the pH was still low (3.99) and Al was very high (10.22 cmolc/kg soil). For 

T7, where 4 t GML/ha were applied in combination with fused magnesium phosphate, the yield was not 

significantly different from that of T6. It means instead of using organic fertilizer, farmers in that area can 

apply lime together with fused magnesium phosphate. The Malaysian government gives farmers in the area 

this phosphate fertilizer as a subsidy to increase rice production. 

INTRODUCTION 

The Kemasin-Semerak Integrated Agriculture Development Project was launched by the 

Ministry of Agriculture Malaysia in 1982. The project area is located in the Kelantan 

Plain, an east coast state of Peninsular Malaysia. The Kelantan Plain is in the tropical wet 

climatic zone, with a mean daily temperature of 32 o C and a mean annual rainfall of 

2290-2540 mm [13]. The climate of the area is influenced by the South China Sea during 

the Northeast Monsoon, which is from November to January. 

The Kelantan Plain consists of a mixture of riverine and marine alluvial soils, 

formed as a result of the rise and fall in sea level since the Quaternary [4]. Peaty materials 

sometimes overlain by mixed clayey-sandy sediments occasionally with variable amounts 

of pyrite are scattered all over the plain, especially along the coastline. This eventually 

gives rise to development of acid sulfate soil conditions, which are harmful to rice. 

About 80 % of the people in the area involve in farming activities, particularly 

rice production. Unfortunately, some of the soils in the rice farms are too acidic for rice 

cultivation, having a pH value of less than 3.5. They are called acid sulfate soils. Under 

this condition, Al and Fe contents in the solutions are usually very high. Rice yield for 

133


these soils is very low (ranging from 1.29 to 3.06 t/ha). Among the agronomic problems 

common to acid sulfate soils are toxicity due to the presence of Al, decrease on P 

availability, nutrient deficiency, Fe(II) toxicity and plant stress due to the presence of 

sulfuric horizon [3]. 

The activities of Al 3+ in the soil solution are controlled by Al(OH)3 (gibbsite), but 

only at high pH. Thus, raising the pH would render the Al inactive, as gibbsite is inert. Al 

in soil solution at 1-2 mg/kg can be toxic to rice [5]. 

With organic material, Fe(II) toxicity may occur due to reduction of Fe(III) under 

flooded soil conditions [20]. According to Moore and Patrick [9], Fe(II) activities were 

seldom equilibrium with iron solid phases in acid sulfate soils. Ponnamperuma et al. [15] 

reported values of 5000 mg/kg Fe(II) within 2 weeks of flooding. Iron uptake by rice is 

correlated with Fe 2+ activities in soil solution [9]. Concentration above 500 mg/kg Fe(II) 

is considered toxic to rice plants planted on acid sulfate soils [12]. 

Some areas of acid sulfate soils in Malaysia have been reclaimed for rice 

cultivation using ground magnesium limestone (GML). In the acid sulfate soils of the 

Muda Agricultural Development Authority (MADA) granary areas in Kedah-Perlis 

coastal plains (northwest coast of Peninsular Malaysia), for instance, rice yield improved 

significantly after applying 2.5 tonnes of ground magnesium limestone per ha [2]. In 

another area called Merbok Scheme (also in the Kedah-Perlis coastal plains), rice yield 

increased from 1.4 t/ha (in 1974) to 4.5 t/ha (in 1990) after yearly application of 2 t 

GML/ha [19]. 

Acid sulfate soils can also be ameliorated by application of organic materials [10]. 

Application of organic matter in Al-toxic soils increases yield by detoxification of Al 

through pH increase and complexation of Al by organic matter [7]. The slight increase in 

soil pH can be due in part to release of NH3 during decomposition of organic matter as 

being reported for green manure [6]. 

The objective of this study was to ameliorate an acid sulfate soil using ground 

magnesium limestone and an organic-based fertilizer for rice cultivation. 

The soils 


The soils in the experimental plots belong to the Nipis-Bakri Associations (organic soils 

underlain by sulfidic materials with 50 cm depth), which can be classified as Typic 

Sulfosaprists. The peaty materials have been degraded as a result of a long history of rice 

cultivation. In the soil profile, the sulfuric layer occurs below the depth of 45 cm. 

Prior to treatment, soil samples were collected at 15 cm interval to the depth of 75 cm at 

selected locations in the experimental plots (T1, T3, T5) in order to determine the initial 

chemical properties of the soils. Further soil samplings were carried out after every rice 

harvest for every treatment in the trial, but only for the topsoil. 

The crop tested 

The rice (Oryza sativa) variety used in the trial was MR 219. This is the most common 

rice variety planted by Malaysian rice growers in the Kelantan Plain. The past harvest 

134


showed that this rice variety yields about 2 t/ha using farmer’s practice, which is below 

the national average of 3.8 t/ha. 

Experimental 

The experiment was laid out in the field using Completely Randomized Design, with five 

replications. Each experimental plot size was 3X3 meters. There were altogether seven 

treatments. The treatment for the trial included a control (no lime, T1); the rest of the 

treatments are given in Table 1. The amount of organic fertilizer applied was 0.25 t/ha. 

Symbol Treatment 

T1 Control (0 t GML/ha) 

T2 2 t GML + /ha 

T3 4 t GML/ha 

T4 6 t GML/ha 

T5 8 t GML/ha 

T6 4 t GML/ha + JITU* 

T7 4 t GML/ha + FMP # 

+ GML – Ground Magnesium Limestone 

* JITU – Sugar cane-based organic fertilizer (0.25 t/ha) 

# FMP – Fused Magnesium Phosphate 

Table 1: Treatment in the field 

The main rice season in the Kelantan Plain is November-April, while the offseason 

is May-September. For this trial, two successive crops of rice were planted, during 

the main season. Ground magnesium limestone (GML) was applied once in mid-October 

2002 and the seeding was done two weeks later, just before irrigation water was allowed 

to flow into the experimental plots. 

Standard fertilizer rates were give to the growing rice plants in the field (90-120 

kg N/ha, 12-18 kg P/ha, 90-120 kg K/ha), using urea, NPK Blue (12:12:17+TE) and NPK 

Green (15:15:15+TE) as the sources of the nutrients. This rate was for optimal rice 

growth, which was slightly higher than that using farmer’s practice. The organic fertilizer 

used was sugar cane-based compost. 

Soil analysis 

The soil pH (1:2.5) was determined in water. The cation exchange capacity (CEC) was 

determined using NH4OAc, buffered at pH 7. Exchangeable Ca, Mg, and K in the 

NH4OAc extract were determined by atomic absorption spectrometry (AAS). 

Exchangeable Al was extracted by I M KCl and determined by AAS. The organic carbon 

was determined by the standard Walkley-Black method [21]. 

135


Iron in the soils was determined by double acid method (henceforth referred to as 

acid-extractable Fe). It was extracted using 0.05 M HCl in 0.0125 M H2SO4. A five-gram 

sample of the soil was mixed with 25 mL of the extracting solution and shaken for 15 

minutes. The solution was then filtered through Whatman filter paper number 42 before 

determining the Fe it contained by AAS. 

The initial soil chemical properties 


The chemical characteristics by depth of the soils at selected locations of the 

experimental plots in the trial before treatment are given in Table 2. The topsoil pH was 

low; the values were even lower at the depth below 50 cm. At the depth of 45-60 cm, the 

pH values were lower than 3.5 in all the three locations in the experimental plot (Table 

2). This low pH coinciding with the presence of jarositic mottles in the soils at that depth 

qualifies them to be classified as acid sulfate soils. According to a study conducted in 

Vietnam, the depth of jarositic layer in an acid sulfate soil is not related with rice 

productivity [8] 

The low pH was consistent with the presence of high exchangeable Al, especially 

at depth below 45 cm, which were the sulfuric layers. But in the Kelantan Plain, the 

exchangeable Ca and Mg were very low [18]. Hence, liming is necessary to supplement 

the macronutrients. 

It was found that the peaty materials were completely decomposed. The CEC 

(data not shown) of less than 20 cmolc/kg soil further proves that the organic had broken 

down and completely mixed with mineral sediments. The CEC of normal organic matter 

is very high, having a value more than 200 cmolc/kg. According to the soil taxonomy 

[17], these soils can be classified as Typic Sulfosaprists due to the presence of peaty 

materials and sulfuric horizon within the depth of 50 cm. 

The initial topsoil exchangeable Ca ranged from 1.17 to 1.68 cmolc/kg soil, lower 

than the required level for rice of 2 cmolc/kg soil [14]. The initial exchangeable Mg was 

only 0.50-0.53, but Mg requirement is 1 cmolc/kg soil [5]. According to these researchers 

also, Al concentration of 1-2 mg/kg in the soil solution would cause toxicity to the 

growing rice plants. Potassium contents seemed to be moderately high and thus would be 

sufficient for rice growth. 

Based on the presence of deficient amounts of the two macronutrients (Ca and 

Mg), it is appropriate that the infertility of the soils can in part be ameliorated by 

application of dolomitic limestone, which contains both elements. 

The effects of treatment on soils 

Flood occurred twice in late November 2002. It is not possible to estimate how much 

damage the flood had caused to the rice production. The soil analyses carried out on the 

soil samples after the first rice harvest (sampled in April 2003) showed unexpected 

results. For instance, in T1, the topsoil pH, exchangeable Al, exchangeable Ca and 

136


T1 T3 T5 

Depth pH Al Ca Mg K O.C pH Al Ca Mg K O.C pH Al Ca Mg K O.C 

(cm) air- 

fresh --------------(cmolc/kg)-------------- % 

air- ------------(cmolc/kg)------------ % air- -----------(cmolc/kg)----------- % 

drieddrieddried 

1:2.5 

1:2.5 

1:2.5 

1:2.5 

0-15 4.1 4.7 4.46 0.36 0.18 1.21 10.4 4.2 3.35 0.27 0.13 0.88 21.5 4.4 2.72 0.46 0.18 2.20 25.6 

15-30 4.0 4.5 4.84 0.22 0.14 1.30 - 4.0 4.81 0.36 0.18 0.86 - 3.8 5.94 0.23 0.12 0.41 - 

30-45 3.6 4.4 8.29 0.20 0.52 1.81 - 3.7 8.74 0.32 0.47 1.23 - 3.5 8.82 0.16 0.39 1.32 - 

45-60 2.9 3.9 12.54 0.08 0.33 0.61 - 3.3 8.76 0.31 0.54 1.09 - 3.1 13.54 0.27 0.65 0.99 - 

60-75 2.5 4.1 15.10 0.05 0.15 0.13 - 2.5 32.43 0.07 0.37 0.76 - 2.5 26.73 0.25 0.68 0.75 - 

Table 2: Relevant chemical properties of the soil 

Treatment 

pH 

water 

1:2.5 

Al Ca Mg K 

----------------------(cmolc/kg)---------------------- T1 3.95 e 12.75 a 1.58 e 0.48 f 0.41 a 

T2 3.99 e 10.22 ab 1.99 de 0.57 e 0.24 bc 

T3 4.06 de 9.45 ab 2.22 cd 0.70 d 0.15 d 

T4 4.35 b 3.13 c 2.81 b 0.93 b 0.19 bcd 

T5 4.52 a 2.37 c 3.74 a 1.10 a 0.17 cd 

T6 4.21 bc 8.79 ab 2.57 bc 0.79 c 0.27 b 

T7 4.16 cd 7.46 bc 2.47 bc 0.78 cd 0.21 bcd 

LSD0.05 0.14 5.15 0.47 0.08 0.08 

Table 3: Topsoil pH and exchangeable cations after 2 nd harvest 

137


exchangeable Mg were 3.95, 5.83, 1.06 and 0.46 cmolc/kg soil, respectively (data not shown). 

In the T5, where 8 tonnes/ha of GML were applied, the corresponding values were 4.38, 2.64, 

2.86 and 1.21 cmolc/kg soil. Ironically, the respective values for T7 were higher than those of 

the T5, where only 4 tonnes/ha of GML were applied. The corresponding values for this 

treatment were 4.93, 0.12, 8.60, 3.37 cmolc/kg soil. All these would be seen in the response 

of the rice plants shown by the yield of rice in this trial in the 1 st season. However, the effect 

of this flood on rice yield was less remarkable in the 2 nd season. 

The results of the soil analyses for the second season (sampled on May 1, 2004) were 

according to expectation. The lowest pH with a value of 3.95 was reported for the control. 

The highest pH, being 4.52, was reported for T5, where the most amount of GML was 

applied (Table 3). Consistent with the lowest pH, the control treatment had the highest value 

of exchangeable Al, with a value of 12.75 cmolc/kg soil. As a result of the GML application, 

soil pH slowly but surely increased, culminating in the T5. In this treatment, the 

exchangeable Ca and Mg were the highest in the trials, having values of 3.74 and 1.10 

cmolc/kg soil, respectively. The increase in pH was concomitantly followed by the lowering 

of exchangeable Al in the soil, the value of Al being 2.37 cmolc/kg soil. This was the lowest 

value of exchangeable recorded for this trial. 

Rice yield in the 1 st season 

The two floods of November of 2002 had affected the growing rice seedlings. After the 

floods, some plots needed to be reseeded (by transplanting). There could also be removal of 

the some liming materials by the running water during the height of the flood period; each 

flood lasted for about a week. The effect of the flood is clearly seen in the erratic values of 

the rice yield (Table 4). There seemed to be no real difference in rice yield between 

treatments. Note that the highest yield was seen on T2, where 2 t GML/ha was applied. But 

this yield was not significantly different from the control. The result of the trial for the 2 nd 

would be presented later. 

Treatment 

First harvest 

April 26, 2003 

(t/ha) 

138 

Second harvest 

May 1, 2004 

(t/ha) 

T1 4.5 ab 5.1 bc 

T2 5.0 a 4.5 c 

T3 3.5 bc 6.3 abc 

T4 4.4 abc 6.6 ab 

T5 4.2 abc 7.2 a 

T6 3.7 bc 7.5 a 

T7 3.1 c 6.8 ab 

LSD0.05 1.4 2.0 

Table 4: The rice yield at the first and second harvest 

Seeding of the 1 st planting season was done two weeks after lime treatment. This is 

considered a long enough time for the lime to react with soil, given the acid soil conditions at 

the site. The rice yield for the recommended rate (T6) was 3t/ha; this was lower than that of 

the control though it was not significantly different.


Rice yield in the 2 nd season 

The highest rice yield for the 2 nd season was 7.5 t/ha obtained by T6 (Table 4). For this 

treatment, 4 t GML/ha were applied in combination with 0.25 t/ha sugarcane-based organic 

fertilizer (JITU). This yield is comparable to the yield of rice grown on good soils in the 

granary areas of the west coast of the peninsula. 

It was observed that the yield obtained by T6 was not significantly different from that 

of the T3, T4 and T5. There was indication that applying 2 t GML/ha (T2) is not enough to 

ameliorate the soil for rice cultivation. As Table 3 shows, for the T2, the pH was still low 

(3.99) and Al was very high (10.22 cmolc/kg soil). For T7, where 4 t GML/ha were applied in 

combination with fused magnesium phosphate, the yield was not significantly different from 

that of the T6. It means that instead of using organic fertilizer, farmers in that area can apply 

lime together with fused magnesium phosphate. 

General discussion 

Ca present in soils is good in itself. Ca is, to a certain extent, able to reduce the toxic effect of 

Al [1,16]. This would happen from T3 right to T7 (Table 3). The amelioration of Al toxicity, 

should there be any, would be shown by the increase in rice yield (Table 4). The presence of 

extra Mg could also contribute to alleviation of Al toxicity as had been shown by 

Shamshuddin et al. [16] for maize. 

Aluminum is toxic to plant. High exchangeable Al in soil is usually associated with 

low pH. This is clearly shown by the data given in Table 3; the lowest pH coincides with the 

highest Al (T5). It shows the opposite in T1. As seen in Table 1, the initial exchangeable Al 

was extremely high in some samples, reaching a value of 32.43 cmolc/kg soil in the subsoil of 

T3. The lowest value was 2.72, in the topsoil of T5. In the water in the vicinity of the 

experimental plots, Al would certainly exceed the critical value for rice production of 1-2 

mg/kg. This high Al in the solution can be reduced to an accepted level by applying GML at 

an appropriate rate. This study suggested that GML application at 4 t/ha would be 

appropriate. 

Fe toxicity is one of the most important problems facing production of rice on acid 

sulfate soils. In the abandoned rice fields, the water was reddish in color, indicating the 

presence of high amounts of soluble iron. In this study, acid-extractable Fe in the soils was 

slightly above the critical level, ranging from 0.07 to 0.81 cmolc/kg soil (data not shown). 

Critical Fe concentration varies from 0.05 to 5.37 cmolc/kg soil [5] implying that Fe may not 

be the only source of soil toxicity that causes reduction in yield. 

A major problem of cultivated rice on acid sulfate soils is P-deficiency. This is caused 

by high P-fixation capacity of the soil due to the presence of high amounts of Al and/or Fe. P 

is unavailable to the rice and will remain in place where it is applied due to its 

immobilization. So, once soluble phosphate fertilizer is applied, it will revert to its less or 

insoluble form. Lack of P in the soil can be alleviated by applying fused magnesium 

phosphate (T7). 

P-deficiency in the soil would cause stunted growth, reduced tillering and reduction in 

the number of panicles. In the 2 nd season, the available P was about 4 ppm (data not shown), 

and there was no significant difference between treatments. But the rice yield did not seem to 

be affected significantly by the possible lack of available P in the soils, as the yield in T6 and 

T7 had shown. The required soil available P for rice production is 7-20 ppm [5]. 

Adding organic fertilizer into a flooded acid sulfate soil would intensify reducing 

condition, resulting in release of Fe 2+ , which is toxic to rice plants [20]. Putting organic 

fertilizer at the rate applied in the current study did not show any effect on rice yield. 

139


Treatment T6 in which GML applied together with organic fertilizer gave the highest rice 

yield of 7.5 t/ha in 2 nd season (Table 4). On the contrary, high quality organic matter, like 

organic fertilizer used in the current study, would hasten reduction of Fe that result in pH 

increase [11]. 

The lime (GML) used in this study was dolomitic limestone [(Ca,Mg) (CO3)2 ]. 

Adding this lime would increase soil pH accordingly, with concomitant addition of Ca and 

Mg into the soil. For 2 nd season of the trial, soil pH increased linearly with increasing 

exchangeable Ca (Figure 1A), with R 2 = 0.73. Likewise, pH increased linearly with 

increasing exchangeable Mg (Figure 1B; R 2 = 0.78). 

pH 

4.80 

4.60 

4.40 

4.20 

4.00 

3.80 

3.60 

y = 0.26x + 3.54 

R 2 = 0.73 

- 1.00 2.00 3.00 4.00 5.00 

exchangeable Ca 

140 

pH 

4.80 

4.60 

4.40 

4.20 

4.00 

3.80 

3.60 

y = 0.26x + 3.54 

R 2 = 0.73 

- 1.00 2.00 3.00 4.00 5.00 


A B 

Figure 1. Relationship between pH and exchangeable Ca (A) and exchangeable Mg (B) 

GML ameliorated in the soil according to the following reactions: 

(Ca,Mg)(CO3)2 � Ca 2+ + Mg 2+ + CO3 2- (equation 1) 

CO3 2- + H2O � HCO3 - + OH - (equation 2) 

Al 3+ + 3OH - � Al(OH)3 (equation 3) 

The GML dissolved readily on applying it into the acidic soil, releasing Ca and Mg (equation 

1), and these macronutrients could be taken up the growing rice plants. Subsequently, 

hydrolysis of CO3 - (equation 2) would produce hydroxyls that neutralized Al by forming inert 

gibbsite (equation 3). Soil pH increased significantly following reduction of exchangeable Al 

(Figure 2A).


pH 

4.80 

4.60 

4.40 

4.20 

4.00 

y = -0.23Ln(x) + 4.59 

R 2 3.80 

3.60 

= 0.59 

- 5.00 10.00 15.00 20.00 

exchangeable Al 

141 

pH 

4.80 

4.60 

4.40 

4.20 

4.00 

3.80 

y = 0.19Ln(x) + 4.36 

R 2 = 0.71 

3.60 

- 1.00 2.00 3.00 4.00 5.00 

Ca/Al ratio 

A B 

Figure 2: Relationship between pH and Al(A) and Ca/Al ratio (B) 

Calcium is able to detoxify Al to certain extent [1]. Hence, Ca/Al ratio can be used as 

an index of soil acidity [16]. Unfortunately, there was no correlation between rice and Ca/Al 

ratio in this study. Neither was there a correlation between relative yield and Ca/Al ratio. 

However, there was an excellent correlation between pH and Ca/Al ratio. This is shown by 

the equation in Figure 2B: 

pH = 0.19Ln(x) + 4.36 (R 2 = 0.71) 

Figure 3 depicts the relationship between yield and relative yield with either 

exchangeable Ca or Mg in the acid sulfate soil. The correlation between yield and 

exchangeable Ca was poor, with low R 2 value (Figure 3A). The Pearson Correlation 

Coefficient was 0.32 with probability of 0.058. Thus, the relationship between the two 

parameters was significant at 5 % level. The same is true for the correlation between relative 

yield and exchangeable Ca (Figure 3B). As the relationship is poor, it is unable to determine 

the critical exchangeable Ca for rice cultivation on this particular acid sulfate soil. There is 

indication that rice yield improves on GML application.


Yield (t/ha) 

Relative Yield (%) 

12 

10 

8 

6 

4 

2 

A 

y = 0.78x + 4.35 

- 

- 1.00 2.00 3.00 4.00 5.00 


120 

100 

80 

60 

40 

20 

- 

B 

y = 7.86x + 43.84 

- 1.00 2.00 3.00 4.00 5.00 


142 

Yield (t/ha) 

Relative Yield (%) 

12 

10 

8 

6 

4 

2 

C 

y = 3.44x + 3.65 

- 

0.20 0.40 0.60 0.80 1.00 1.20 

exchangeable Mg 

120 

100 

80 

60 

40 

20 

- 

D 

y = 34.65x + 36.84 

0.20 0.40 0.60 0.80 1.00 1.20 

exchangeable Mg 

Figure 3. Relationship between rice yield and exchangeable Ca (A), relative yield and exchangeable 

Ca (B), yield and exchangeable Mg (C) and relative yield with exchangeable Mg (D) for the second 

season. (R 2 < 0.01) 

Further indication of the improvement of rice yield due to GML application is shown 

in Figure 3C and 3D, where yield and relative yield, respectively when exchangeable Mg was 

increased. 

CONCLUSIONS 

Ground magnesium limestone and organic fertilizer applied at appropriate rates on acid 

sulfate soils can produce rice yield comparable to that of the granary areas of Malaysia. The 

result of this study showed that rice yield could be as high as 7.5 t/ha using current 

technology, applying 4 t GML/ha in combination with an organic fertilizer.


ACKNOWLEDGENTS 

The authors would like to thank Universiti Putra Malaysia and the Ministry of Science, 

Technology and Innovation Malaysia for financial and technical support. 

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Netherlands, pp: 391-406, (1973). 

[16] J. Shamshuddin, I. Che Fauziah, H.A.H. Sharifuddin. Effects of limestone and gypsum application to a 

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]17] Soil Survey Staff. Soil Taxonomy: A Basic Soil Classification for Making and interpreting Soil Surveys. 

USDA, Natural Resources Conservation Services, Washington, DC, (1999). 

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Dent, D.L., Mensvoort, M.E.F., Eds.; Publ. 53, Wageningen, The Netherlands, pp: 95-101, (1993). 

[20] K.T. Tran, T.G. Vo. Effects of mixed organic and inorganic fertilizers on rice yield and soil chemistry of 

the 8 th crop on heavy acid sulfate soil (Hydraquentic Sulfaquepts) in the Mekong Delta of Vietnam. A paper 

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143

Workshop IC-PLR 2006 – Theme C – Land Evaluation and Land Degradation 

WORKSHOP THEME C – LAND EVALUATION AND LAND 

DEGRADATION 

Sub-theme : Land evaluation for sustainable land management & policy 

making 

A. Verdoodt, E. Van Ranst 

Paper/poster : Oil palm and rubber production model for substituting 

rubber with oil palm and evaluating to establish oil palm into Northeast 

Thailand – S. Pratummintra, E. Van Ranst, H. Verplancke 

Paper/poster : Soil properties and biological diversity of undisturbed and 

disturbed forests in Mt. Malingdan, Philipines - Renato D. Boniao, Rosa 

Villa B. Estoista, Carmelita G. Hansel, Ron de Goede, Olga M. Nuneza, 

Brigida A. Roscom, Sam James, Rhea Amor C. Lumactud, Mae Yen O. 

Poblete, Nonillon Aspe 

Sub-theme : Land degradation : pressures, indicators and responses 

W. Cornelis, D. Gabriels, H. Verplancke 

Paper/poster : Indicators and participatory methods for monitoring land 

degradation. A case study in the Migori district of Kenya – Vincent de 

Paul Obade, Eva De Clercq 

Paper/poster : Proposed plan of action for research on desertification in 

the Sudan : Gezira and Sennar States – Kamal Elfadil Fadul, Fawzi 

Mohamed Salih 

Paper/poster : Diagnostic of degradation processes of soils from Northern 

Togo (West Africa) as a tool for soil and water management – Rosa M. 

Poch, Josep M. Ubalde 

Conclusions 

144


Sub-theme : LAND EVALUATION FOR SUSTAINABLE LAND 

MANAGEMENT & POLICY MAKING 

Overview of the latest research in land evaluation at the Laboratory of Soil Science 

A. Verdoodt & E. Van Ranst 

Laboratory for Soil Science, Ghent University, Gent, Belgium 

New paradigms interpret soil as a habitat for living systems, delivering a wide range of 

hugely valuable ecosystem functions such as food security, clean air and water, biodiversity, 

and cultural heritage. Soil erosion, contamination, and organic matter decline, are only a few 

examples of threats that hypothecate soil functioning all over the world. Although there is 

good agreement on the importance that should be given to sustainable land management, 

understanding about how the principal drivers and configurations of the soil system differ 

between ‘land-use-soil-climate’ combinations is still incomplete and hampers the 

development of scientifically sound land use policies. In response to these new demands, the 

research in land evaluation conducted at our laboratory focuses on three major aspects : 

(1) design of soil/land information systems providing georeferenced climate, landscape and 

soil data; 

(2) design of land evaluation tools for specific land uses, making full use of the increased 

availability of soil data; and 

(3) identification of soil quality indicators, baselines and thresholds for monitoring soil 

quality and designing soil protection policies. 

In the first research aspect, land and soil information systems, together with the new 

techniques of data gathering based on remote sensing, have become indispensable tools for 

the presentation and analysis of soil characteristics. Geographic information science and 

relational database software were combined to capture the spatial as well as the numerical 

and descriptive data gathered during the traditional soil surveys organised in Rwanda and the 

Democratic Republic of Congo. The soil information system of Rwanda, comprising 43 soil 

maps and 43 digital terrain models at a scale of 1:50,000, was further extended with climatic 

records at monthly and daily temporal resolutions. Additionally, the generation of simplified 

soil maps at scale 1:250,000, revealed the diversity in land resources at national level. With 

the creation of a soil profile database, containing 1,834 described and analysed soil profiles, 

the soil information system is a powerful tool for agricultural and land use planning purposes 

in Rwanda. A similar soil information system is being created for the Democratic Republic of 

Congo. In addition, the detailed, semi-detailed and reconnaissance soil maps and the 

abundant morphological and analytical soil profile data gathered in Rwanda, Burundi and the 

DR of Congo, enabled us to develop a scientifically sound Great Lakes Area SOTER (Soil 

and Terrain) Database. SOTER mapping is similar to physiographic soil mapping but with 

stronger emphasis on the terrain-soil relationship. A SOTER unit represents a unique 

combination of terrain and soil characteristics. The methodology focuses on the identification 

of areas of land with a distinctive pattern of landform, lithology, surface form, slope, parent 

material and soil. During the design of the SOTER database of Central Africa, a 

physiographic map has been derived after analysis of SRTM satellite data of the region. 

Geological maps at different scales were translated into lithological maps. These thematic 

maps were combined to give the SOTER unit maps at scale 1:1M for Rwanda and Burundi 

145


and at scale 1:2M for the Democratic Republic of Congo. Much more additional information 

characterising the non-mappable terrain and soil components has been selected, harmonised 

and inserted in a large relational database containing a wealth of descriptive and analytical 

soil profile data. 

The second research aspect comprises the development of (1) a spatially and 

temporally explicit multi-scale decision support system that reveals the biophysical indicators 

affecting land use choices of different stakeholders, and (2) a web-based land evaluation 

system to perform agricultural productivity assessments in developing countries. The multiscale 

decision support system comprises three different environmental assessment tools, 

designed to run with data supplied by traditional soil surveys and organised into a land 

information system. A qualitative land suitability classification procedure is adapted to 

translate the large-scale biophysical data, into five suitability classes. At local scale, the 

productivity of the soil units is estimated using a three-level hierarchical crop productivity 

estimator. At the smallest spatial and temporal resolution, a daily water balance approach is 

linked to a crop growth model. The decision support system was applied and validated using 

the land information system of Rwanda. It revealed the biophysical properties affecting 

national crop regionalisation, regional crop productivity differences, and local intensification 

options. The Web-based land evaluation system (WLES) is designed in such a way that the 

system operates either as a Web Application or as a Web Service via the Internet. 

Implemented on top of the .NET platform, the WLES has a loosely coupled multi-tier 

structure which seamlessly integrates the land evaluation knowledge engine and the spatial 

database. The WLES not only provides productivity assessment service in a user-friendly 

way to agricultural researchers, engineers, farm managers, policy makers and planners but 

also acts as a building block of a larger system such as that of land taxation, impact of climate 

change on agriculture, population carrying capacity, and so forth. 

The third research aspect merely focuses on the assessment of the overall soil 

quality, reflecting the capacity of the soil to function sustainably. This encompasses the 

identification and selection of scientifically sound soil quality indicators to monitor the 

changes in the soil quality status. These changes are determined relative to a baseline value 

and are also compared to a threshold value, indicating a critical soil status limiting or 

threatening the sustainable functioning of the soil. The ongoing ENVASSO (ENVironmental 

ASsessment for SOil monitoring) project reviews and defines indicators that encompass the 

main threats to soil degradation in Europe. Identification of the soil quality indicators for 

each threat is based on an extensive literature review with the reports of technical working 

groups within the development of the EU Thematic Strategy on Soil Protection as main 

source documents. Selection criteria for each indicator are based on its significance, 

analytical soundness, measurability, policy relevance, geographical coverage, availability of 

baselines and thresholds and its comprehensibility. Protocols and procedures for data 

collection, sampling, storage, manipulation, interpretation and reporting will be developed. 

The project will report the current monitoring of the soil quality indicators, will identify gaps 

in the national and European wide monitoring systems and will provide guidelines for the 

development of a soil policy. Soil mapping and identification of sound soil quality indicators 

can also be realised through the incorporation of ethnopedological knowledge. In Mexico, a 

local soil classification scheme was formalised and compared to the international USDA soil 

classification system. Both similarities and differences, revealing complementarities, were 

identified. Critical is the evaluation of the topsoil characteristics, as the monitoring of the 

topsoil dynamics is fundamental to sustainable land management. In a study for sustainable 

land management of mountain karst areas in Vietnam, local inhabitants are also participating 

in the generation of soil maps and the identification and classification of local indicators of 

soil quality. Laboratory results confirmed the validity of vernacular knowledge for 

146


identifying and classifying local indicators of soil quality and soil fertility, compared to 

scientific standards applied in Vietnam and in the international community. 

REFERENCES 

Research papers, Laboratory of Soil Science 

[15] N. Barrera-Bassols, J.A. Zinck, E. Van Ranst. Symbolism, knowledge and management of soil and land 

resources in indigenous communities : ethnopedology at global, regional and local scales. Catena 65, pp. 118- 

137 (2006). 

[16] N. Barrera-Bassols, J.A. Zinck, E. Van Ranst. Local soil classification and comparison of indigenous and 

technical soil maps in a Mesoamerican community using spatial analysis. Geoderma (in press, 2006). 

[17] B. Mintesenot, H. Verplancke, E. Van Ranst, H. Mitiku. Examining traditional irrigation methods, irrigation 

scheduling and alternate furrows irrigation on Vertisols in Northern Ethiopia. Agricultural Water Management 

64, pp. 17-27 (2004). 

[18] D. P. Shrestha, J. A. Zinck, E. Van Ranst. Modelling land degradation in the Nepalese Himalaya. Catena 

57, pp. 135-156 (2004). 

[19] H. Tang, E. Van Ranst. Is highly intensive agriculture environmentally sustainable? A case study from 

Fugou county, China. Journal of Sustainable Agriculture 25 (3), pp. 91-102 (2005). 

[20] H. Tang, J. Qiu, E. Van Ranst, C. Li. Estimations of soil organic carbon storage in cropland of China based 

on DNDC model. Geoderma 134, pp. 200-206 (2006). 

[21] E. Van Ranst, F. O. Nachtergaele, A. Verdoodt. Evolution and availability of geographic databases. In : 

Innovative techniques in soil survey : “Developing the foundation for a new generation of soil resource 

inventories and their utilisation”. H. Eswaran, P. Vijarnsorn, T. Vearasilp, E. Padmanabhan (eds.). Land 

Development Department, Chattuchak, Bangkok, Thailand, pp. 223-236 (2004). 

[22] Van Vosselen, H. Verplancke, E. Van Ranst. Assessing water consumption of banana : traditional versus 

modelling approach. Agricultural Water Management 74, pp. 201-218 (2005). 

[23] Verdoodt, E. Van Ranst, W. Van Averbeke. Modelling crop production potentials for yield gap analysis 

under semi-arid conditions in Guquka, South Africa. Soil Use and Management 19, pp. 372-380 (2003). 

[24] Verdoodt, E. Van Ranst, H. Verplancke. Integration of soil survey data, Geographic Information Science 

and land evaluation technology for land use optimisation in Rwanda. In : Innovative techniques in soil survey : 

“Developing the foundation for a new generation of soil resource inventories and their utilisation”. H. Eswaran, 

P. Vijarnsorn, T. Vearasilp, E. Padmanabhan (eds.). Land Development Department, Chattuchak, Bangkok, 

Thailand, pp. 365-380 (2004). 

[25] Verdoodt, E. Van Ranst, L. Ye. Daily simulation of potential dry matter production of annual field crops in 

tropical environments. Agronomy Journal 96, pp. 1739-1753 (2004). 

[26] Verdoodt, E. Van Ranst, L. Ye, H. Verplancke. A daily multi-layered water balance to predict water and 

oxygen availability in tropical cropping systems. Soil Use and Management 21, pp. 312-321 (2005). 

[27] Verdoodt, E. Van Ranst. Environmental assessment tools for multi-scale natural resources information 

systems. A case study of Rwanda. Agriculture, Ecosystems and Environment 114, pp. 170-184 (2006). 

[28] L. Ye, E. Van Ranst. Population carrying capacity and sustainable agricultural use of land resources in 

Caoxian County (N. China). Journal of Sustainable Agriculture 19 (4), pp. 75-94 (2002). 

[29] L. Ye, E. Van Ranst, A. Verdoodt. Design and implementation of a Web-based land evaluation system and 

its application to land value tax assessment using .NET technology. In : Innovative techniques in soil survey : 

“Developing the foundation for a new generation of soil resource inventories and their utilisation”. H. Eswaran, 

P. Vijarnsorn, T. Vearasilp, E. Padmanabhan (eds.). Land Development Department, Chattuchak, Bangkok, 

Thailand, pp. 183-196 (2004). 

[30] L. Ye, E. Van Ranst. Development of a Web-based land evaluation system and its application to population 

carrying capacity assessment using .NET technology. In : Proc. of the AFITA/WCCA 2004 Joint Congress on 

IT in Agriculture. F. Zazueta, S. Ninomiya, R. Chitradon (eds.). National Science and Technology Development 

Agency, Pathumthani 12120, Thailand, pp. 409-414. 

[31] J.A. Zinck, J.L. Berroteran, A. Farshad, A. Moameni, S. Wokabi, E. Van Ranst. Approaches to assessing 

sustainable agriculture. Journal of Sustainable Agriculture 23, pp. 87-109 (2004). 

147


Other interesting papers 

[32] S. S. Andrews, D. L. Karlen, C. A. Cambardella. The soil management assessment framework : a 

quantitative soil quality evaluation method. Soil Science Society of America Journal 68, pp. 1945-1962 (2004). 

[33] M.A. Arshad, S. Martin. Identifying critical limits for soil quality indicators in agro-ecosystems. 

Agriculture, Ecosystems and Environment 88, pp. 153-160 (2002). 

[34] P. S. Bindraban, J. J. Stoorvogel, D. M. Jansen, J. Vlaming, J. J. R. Groot. Land quality indicators for 

sustainable land management : proposed method for yield gap and soil nutrient balance. Agriculture, 

Ecosystems and Environment 81 (2), pp. 103-112 (2000). 

[35] M. R. Carter. Soil quality for sustainable land management : organic matter and aggregation interactions 

that maintain soil functions. Agronomy Journal 94, pp. 38-47 (2002). 

[36] B. Govaerts, K. D. Sayre, J. Deckers. A minimum data set for soil quality assessment of wheat and maize 

cropping in the highlands of Mexico. Soil and Tillage Research 87, pp. 163-174 (2006). 

[37] J. E. Herrick. Soil quality : an indicator of sustainable land management? Applied Soil Ecology 15, pp. 75- 

83 (2000). 

[38] E. M. Hillyer, J. F. McDonagh, A. Verlinden. Land-use and legumes in northern Namibia – The value of a 

local classification system. Agriculture, Ecosystems and Environment (in press, 2006). 

[39] M. Igué, T. Gaiser, K. Stahr. A soil and terrain digital database (SOTER) for improved land use planning in 

Central Benin. European Journal of Agronomy 21, pp. 41-52 (2004). 

[40] R. Mermut, H. Eswaran. Some major developments in soil science since the mid-1960s. Geoderma 100, pp. 

403-426 (2001). 

[41] E. W. Murage, N. K. Karanja, P. C. Smithson, P.L. Woomer. Diagnostic indicators of soil quality in 

productive and non-productive smallholders’fields of Kenya’s Central Highlands. Agriculture, Ecosystems and 

Environment 79, pp. 1-8 (2000). 

[42] S. A. Rezaei, R. J. Gilkes, S. S. Andrews, H. Arzani. Soil quality assessment in semi-arid rangeland in Iran. 

Soil Use and Management 21, 402-409 (2005). 

[43] R. Ryder. Local soil knowledge and site suitability evaluation in the Dominican Republic. Geoderma 111, 

pp. 289-305 (2003). 

[44] D. Wu, Q. Yu, C. Lu, H. Hengsdijk. Quantifying production potentials of winter wheat in the North China 

Plain. European Journal of Agronomy 24, pp. 226-235 (2006). 

148


OIL PALM AND RUBBER PRODUCTION MODEL FOR 

SUBSTITUING RUBBER WITH OIL PALM AND EVALUATING 

TO ESTABLISH OIL PALM INTO NORTHEAST THAILAND 

Abstract 

S. Pratummintra 1 , E.Van Ranst 2 , H.Verplancke 2 , A. Verdoodt 2 

1 Department of Agriculture, Bangkok, Thailand. 2 Ghent University, Ghent, Belgium. 

Oil palm (Elaeis guineensis Jacq.) is a cash crop that can be exploited all the year round. However, up to now, 

oil palm production in Thailand has been very low because of some limiting climatic, edaphic, crop-specific and 

management parameters. Especially the soil water deficit reported is restricting oil palm yields. The crop evapotranspiration 

in an immature state (1-7 years) was about 4.5-5.0 mm.d -1 , while the mature palm need more 

amounting to about 5.0-5.5 mm.d -1 . These requirements further increase from 6.5-7.5 mm.d -1 in drought period, 

depending on soil texture and soil water content. An area of about 2.012 million rais (0.32 million hectare ) of 

oil palm plantation was identified from the LANDSAT 5 TM image data (date in 2004) and mapped using 

ARCVIEW ver.3.2 a. Land evaluation techniques were designed to classify the plantations based on their 

production potential. They were grouped into 4 potential production classes: (1) higher than 25 ton.ha -1 .yr -1 

(80,708 ha); (2) between 16-25 ton.ha -1 .yr -1 (113,956 ha); (3) between 10-16 ton.ha -1 .yr -1 (125,931 ha) and (4) 

lower than 10 ton.ha -1 .yr -1 being land classified as unsuitable for oil palm (68 ha). Rubber plantation occupying 

about 1.6 million ha in East and South Thailand were identified from the same satellite image data. In addition, 

the rubber planting areas were classified by using the Rubber Production Model. Comparison of the productivity 

of both cash crops resulted in the identification of areas with a rubber productivity less than 1,500 kg.ha - 1.yr -1 

that could be profitably substituted by oil palm, giving a production exceeding 16 ton.ha -1 .yr -1 . Finally, the oil 

palm production model was integrated with a soil water balance model and applied to evaluate the water-limited 

production potential in Thabor, Nongkai Province, where the annual rainfall averaged less than 1,500 mm. One 

found that oil palm should be planted in an area about 20,000 ha and that expected yields are high enough for 

setting-up the bio-diesel project. 

INTRODUCTION 

Oil palm (Elaeis guineensis Jacq.) is one of an economic crop in the southern part of 

Thailand that can be exploited the whole year. However, the production in is limited by many 

parameters related to climate, soil fertility, oil palm variety and management technology. An 

optimized field management is required to continuously maintain a minimum bunch 

production, as oil palm production will be reduced when it is subjected to water stress 

[1,3,6,8,9,11,15]. The optimum average annual rainfall for oil palm is about 2,000 mm with a 

monthly distribution of about 120 mm [5,6]. In Malaysia, the water requirement of oil palm 

were determined by using a lysimeter filled with soil of the Munchong Soil Series (Tropeptic 

Haplorthoxs). One found that the daily potential evapo-transpiration (ETp) during the 

immature stage (1-7 year after planting (YAP)) is about 4.5-5.0 mm, and increased to 5.0-5.5 

mm in a mature stage (more than 8 YAP). In the dry season, the daily ETP increased up to 

6.5-7.5 mm, while it decreased in the rainy season at about 3.0-3.5 mm [4, 12]. 

The drought period affects the physiological process and stomatal resistance of oil 

palm, triggering the closure of the stomata. Consequently, the leaf temperature increases, 

while the rate of photosynthesis was decreased [10]. Upon the decrease in photosynthetic 

assimilates, the rate of female inflorescence abortion increases, while the sex ratio decreases, 

reducing oil palm production [2]. Caliman found that the stomatal resistance of oil palm 

decreased when available soil water content. It mean that the stomatal resistant decreased 

when the soil moisture content decreased. Further research is required to identify the 

149


appropriate management techniques for oil palm plantation in stress area such as Northeast 

Thailand [1]. 

In Thailand, oil palm plantation are extending very quickly, with an estimated area of 

320,000 that will be exploited at the end of 2006. Some of the new plantation areas face 

strong limitations due to low rainfall and high water deficiencies. In these areas, the annual 

water deficit is about 208 to 675 mm within a period of 2-6 months [7,16,17]. Mapping the 

potential production and simulating soil water balance are important tools for guiding the 

farmers in their management strategies, oriented to a maintenance of high yield. 

On the other hand, the Thai government policy has been assigned to control the 

rubber plantation at about 2 million ha in order to maintain a balanced world demand and 

supply, and to stabilize the rubber price. Rubber production area, with a productivity less than 

1,500 kg.ha -1 , will therefore be converted to other economic crops such as oil palm. 

Materials 

This study objectives are; 

1. To locate the oil palm plantation and organize this information to GIS database; 

2. To evaluate and map the production potential of oil palm and rubber; and 

3. To determine the area of rubber that should be substituted with oil palm. 


Digital Images Data and Image Analysis Module 

The Image Analysis is an extension module within ARCVIEW GIS ver. 3.2a. This module is 

use to allocate and map the actual extension of rubber plantations and oil palm orchards from 

the false color composite image by using the visualized technique. The false color composite 

was formulated from 3 bands (5, 3, 2) of the following LANDSAT 5 TM digital data: 

1. Path 127 Row 48, Digital Band 5 3 2, date 26 January, 2005. 

2. Path 127 Row 49, Digital Band 5 3 2, date 20 April, 2004. 

3. Path 127 Row 50, Digital Band 5 3 2, date 7 March, 2004. 

4. Path 128 Row 47, Digital Band 5 3 2, date 16 February, 2004. 

5. Path 128 Row 48, Digital Band 5 3 2, date 2 February, 2005. 

6. Path 128 Row 50, Digital Band 5 3 2, date 6 March, 2005. 

Climate Digital Database 

Climatic data reported during the last twenty years (1986-2005) in the nearby meteorological 

stations were used to run the land suitability model for oil palm. Required input data were 

maps of monthly rainfall, temperature and evaporation. 

Soil survey and analytical data 

The provincial soil maps at a scale of 1:50,000 was used as a basal map for soil surveying. 

Soil sample in each depth were brought up by Edelman Auger and determined moist soil 

color by using Monsel Soil Color Chart, texture by feeling method, structure and clay coating 

by eye lens, pH with soil pH kit. Then, the soil series was determined by comparing the field 

characteristics with the typical soil profile characteristics. On the other hand, a composite 

150


sample of each soil horizon was prepared from 25 sampling pit and use for phisico-chemical 

analysis such as particle size, CEC, available P, %O.C etc. The analytical data of each soil 

were stored in the database. 

Methods 

The procedures in this study were applied from: 

1. The land evaluation technique [18] 

2. The yield gap analysis [19] 

3. The Rubber Production Model [13,14] 

4. The soil water balance [20, 21] 

The environmental crop requirements that need to considered to asses the suitability area for 

oil palm are related to climate and soil as shown in Table 1. 

The steps of working (Fig. 1) started from collecting a climatic and soil data. The 

parametric approach , which mentioned in land evaluation technique, was used to calculate 

the land index by scoring the parameter with the crop requirement table 1). Field surveying 

was done for collecting the field soil data and oil palm yield. Together with the field data and 

land index, the production potential model was classified to 4 classes, named as; 

1. L1 or very suitable (Land index is higher than 76), the production potential is more 

than 25 ton.ha -1 .yr -1 . 

2. L2 or suitable (Land index is 51-75), the production potential is between 13.1-25 

ton.ha -1 .yr -1 . 

3. L3 or marginal area (Land index is 26-50), the production potential is 9.5-13.0 

ton.ha -1 .yr -1 . 

4. L4 is not recommended (Land index is lower than 25). The production potential is 

less than 9.5 ton.ha -1 .y -1 . 

The result of the model was projected in the map with the GIS working scheme (Fig. 

2). 

For rubber, plantations with a potential yield exceeding 1,500 kg dry rubber.0ha -1 .yr -1 

were classified as suitable. All others with a lower production potential should be substituted 

with oil palm to get a better benefit. 

151


Limitation classes and Indexes 

Characteristics 

Class 

Limitation 

S1 

0 1 

S2 

2 

S3 

3 

N 

4 

Index 

Rainfall and Distribution 

100 95 85 60 40 25 0 

Average annual Rainfall (mm) (p) 

2500 

3500 

2000 

3700 

1700 

4000 

1450 

5000 

1350 

5500 

1250 

6000 

600 

7000 

Drought period (months p20 20 18 16 14 12 10 

Annual mean temperature ( °C) >25 25 22 20 18 16 10 

Average annual wind speed (m.s -1 ) 

5 

8 

4 

9 

3 

10 

2 

12 

1 

15 

0 

20 25 

Sunshine radiation (MJ.m 2 ) 

13 

15 

11 

16 

9 

17 

8 

19 

7 

21 

5 

23 

3 

25 

Sunshine ratio (n/N) >0.75 0.75 0.60 0.45 

Topology (%slope) 

Wetness (w) 

0 4 8 16 30 50 80 

Flood Duration 

F0 

F1 F2 

F3 

Drainage classes 

Mod. Well s. poor Poor&aeric Poor v.poor, 

Physical Properties (s) 

Imp. 

but 

drain 

excess. 

Soil texture and structure C>60s SiCL, SCL, SiL, SL, fS Ls, Cm, 

C60v 

s,s,C 

C150 150 100 50 25 15 5 

CaCO 3 (%) 0 1 5 10 15 20 30 

Gypsum (%) 

Soil fertility (f) 

0 0.5 2 3 5 7 10 

Ex. CEC) (cmol (+) kg clay -1 ) >16 16 10 8 6 4 1 

pH 1:1 H2O 5.8 

6.0 

5.5 

6.5 

4.5 

7.0 

3.5 

7.5 

2.5 

8.0 

2.0 

9.0 

1.5 

O.M (%) >1.2 1.0 0.8 0.6 0.4 0.2 0.1 

ECe (dS m -1 ) 0 1 2 3 4 5 6 

After: [13, 18] 

Table 1 (Cont) : Soil characteristics requirement for evaluating for land suitability for oil palm 

152


Climatic data 

- Rainfall 

- Temperature 

- Relative 

humidity 

Parametric Approach 

A1xA2xA3.... 

An 

CI = 2n− 

2 

10 

A = index of parameters 

n = number of parameters 

Land suitability index (LI) 

CIxSI 

LI = 

2 

10 

Soil Characteristics 

WaixFaixPSaixPai 

SI = 

6 

10 

A = index of parameters 

n = number of parameters 

Figure 1 : Working scheme for Land Evaluation for Rubber and Oil Palm 

Physical data 

-Administration Boundary 

- Climatic Database 

- Soil Database 

Map of Production Potential 

-Rubber 

- Oil palm 

Production Potential 

Y = a + b(LI) 

a = intersect 

b = Slope 

Figure 2 : Working scheme for GIS 

153 

Crop Requirement Table 

- Climatic characteristics 

- Soil characteristics 

(Table 1) 

Symbols and Suitability Class 

CI = Climatic indexes 

CI1 = Very suitable, index >75 

CI2 = Suitable, index 51-75 

CI3 = Marginal, index 25-20 

CI4 = Non-suitable, index


Production potential modeling in a pilot area 

The Thai government designed a policy that favors the bio-energy to substitute the petroleum 

energy. Oil palm is one of the oil crops that will be used to produce bio-diesel (B100). The 

target for new oil palm plantings is about 1 million ha. This means that the government needs 

to know which areas are most suitable to establish the new oil palm plantations. 

In Northeast Thailand, a pilot project for oil palm cultivation has been set up. 

However, this area is characterized by low rainfall, high evaporation rates, and high light 

intensities that are serious limitations for oil palm. Therefore, land evaluation models were 

designed and applied to analyse the problem. Soil water balances were studied. Based on that 

information, the area of the Tharbor Irrigation Project was selected for the pilot project. 

The LANDSAT images were use to analyze land cover type and water system (Fig. 

4a). The flooding areas were determined by comparing the GIS data with the image data. The 

ground control points were located with the GPS GARMIN GPS 12 Model. A soil survey 

was performed around the area, and the soil texture was mapped. The irrigation canals were 

also drawn on the map. Fig 4b shows the spatial distribution of soil texture and the irrigation 

system. 

The soil water balance, based on Sys et al. [18] Verplancke [20], was then simulated 

to calculate the soil water deficit or water needs according to soil texture. Finally the 

production potential was mapped (Fig. 4C). 

Oil palm production potential 

RESULTS 

The first step of the land evaluation consisted of an analysis of the climatic data (Fig.3 A-E). 

The suitability classes of climate (Fig.3 F) show that the highly suitable areas are found in the 

South and some regions of East Thailand. 

Extension of Oil Palm Plantations 

The oil palm plantations identified from the LANDSAT images are located in the southern 

provinces occupying an area of 320,138 ha, and in the eastern provinces, occupying an area 

of 1,889 ha. 

The maps of the plantations were overlaid with the production potential maps by 

using the Geoprocessing Module in GIS ARCVIEW 3.2a. Then, the existing area of oil palm 

plantation were classified into the 4 suitability classes (Table 2). The results have been shown 

inTable 2. About 70.0 ha of oilpalm plantations, almost entirely situated in the south were 

classified as “not recommendable”. Next, 124,912.2 ha in the southern and 1,019.5 ha in the 

eastern coast, were classified as marginal for oil palm production. The suitable lands occupy 

113,086.4 ha in South and 869.4 ha in East. And finally, very suitable land was only found in 

the south, with an extension of about 82,071.5 ha. 

154


A Min. Temperature index B Max. Temperature index C Mean temperature index 

D Rainfall index E Drought period index F Climatic index 

Figure 3 : The Result of Climate Classification for Oil Palm by using Parametric Approach 

Production Potential (ton.Ha -1 .year -1 Province Name 

25.0 Total 

Southern Provinces 68.8 124,912.2 113,086.4 82,071.5 320,138.7 

Chumporn - 22,694.9 33,346.9 2,090.1 58,131.7 

Krabi - 45,872.0 38,531.2 59,846.2 144,249.3 

Nakorn Srithammarat - 995.5 177.0 9.4 1,181.9 

Naratiwat 35.7 19.5 510.1 - 565.3 

Pang-nga - 5,450.7 2,522.2 1,759.4 9,732.3 

Pattalung 25.8 - - - 25.8 

Ranong - 1,696.6 - - 1,696.6 

Songkhla - 582.7 3,652.0 - 4,234.7 

Satun - 10,145.9 4,176.6 10,719.0 25,041.6 

Surat Thani - 34,249.9 27,073.8 3,539.2 64,863.0 

Trang - 3,204.3 3,096.8 4,108.2 10,409.1 

Yala 7.2 - - - 7.2 

East Provinces 0.2 1,019.5 869.4 - 1,889.0 

Chonburi - 424.6 814.7 - 1,239.4 

Rayong - 582.4 - - 582.4 

Trad 0.2 12.5 54.6 - 65.6 

Total Area 70.0 125,931.7 113,955.8 82,071.5 322,028.0 

Table 2 : The production potential classification for an existing oil palm plantation 

155


Area of Rubber Plantation 

Analysis of the same LANDSAT images revealed that the total area of rubber is about 1.969 

million ha, mainly located in the south for more than 85% (Table 3). 

Unit : ha 

Province Name 

Low Production Potential 

Low land High land 

High Production Total 

Southern Provinces 278,102.6 422,726.2 998,552.0 1,699,381.0 

Chumporn 43,490.7 0.0 20,601.9 64,092.6 

Krabi 4,865.0 11,689.4 77,253.9 93,808.3 

Nakorn Srithammarat 13,415.8 47,092.8 145,306.1 205,814.7 

Naratiwat 15,845.9 234.9 140,748.0 156,828.8 

Pattani 6,990.7 13,181.3 24,377.4 44,549.4 

Pang-nga 32,302.9 39,542.6 30,449.8 102,295.2 

Pattalung 17,919.4 16,975.4 47,015.8 81,910.6 

Phukhet 216.8 8,559.7 8,817.9 17,594.4 

Ranong 457.6 8,819.4 7,793.9 17,070.9 

Songkhla 58,736.6 77,858.9 85,462.2 222,057.8 

Satun 5,671.7 6,859.5 30,101.1 42,632.3 

Surat Thani 31,421.4 29,519.4 219,858.6 280,799.4 

Trang 38,497.0 34,684.6 133,339.5 206,521.1 

Yala 8,271.2 127,708.5 27,425.8 163,405.4 

East Provinces 45,852.3 23,363.5 140,753.6 209,969.6 

Chanthaburi 14,303.0 5,110.2 33,265.1 52,678.4 

Chonburi 6,998.9 1,189.8 13,432.6 21,621.3 

Chachoengsao 3,591.5 11.4 8,705.8 12,308.6 

Rayong 8,941.9 15,624.2 65,098.2 89,664.3 

Trad 10,942.2 1,396.6 19,338.7 31,677.6 

Prachinburi 0.0 0.0 408.2 408.2 

Srakaew 1,074.9 31.4 505.0 1,611.2 

Total Area 323,954.9 446,089.9 1,139,305.8 1,909,350.6 

Establishing oil palm in northeast Thailand 

Table 3 : An existing area of rubber plantation 

The area of Huimong Irrigation project is about 133,944 ha. An overview of the soils 

identified in the area has been giving in Table 4, summarising the soil series together with 

their national and international classification names. 

156


Soil Series USDA-1975 National 

Borabu fine loamy, mixed, Aquic Plinthustults Red-Yellow Podzolic Soils 

Korat fine loamy, siliceous, Oxic Paleustults Gray Podzolic Soils 

Roiet fine loamy, kaolinitic, Aeric Paleaquults Low Humic Grey Soils 

Renu fine loamy, mixed, Plinthic Paleaquults Hydromorphic Gray Podzolic Soils 

Sanpaya fine loamy, mixed, Typic Ustifluevents AlluvialSoils 

Siton fine loamy, mixed, Aeric Tropaquepts Low Humic Grey Soils 

Satuk fine loamy, kaolinitic, Typic Paleustults Red-Yellow Podzolic Soils 

Tatphanom fine loamy, mixed, Ustic Haplustalfs Non Clacic Brown Soils 

Warin fine loamy, siliceous, OxicPaleustults Red-Yellow Podzolic Soils 

Nakornpanom fine clayey, mixed, Aeric Paleaquults Low Humic Grey Soils 

Pimai fine clayey, mixed, Vertic Tropaquepts Hydromorphic Alluvial Soils 

Phen clayey skeletal, mixed, Typic Plinthaquults Low Humic Grey Soils 

Phonpisai clayey skeletal, mixed, Typic Plinthustults Red-Yellow Podzolic Soils 

Ratburi fine clayey, mixed, Aeric Tropaquepts Hydromorphic Alluvial Soils 

Srisongkham fine clayey, mixed, Vertic Tropaquepts Hydromorphic Alluvial Soils 

Table 4 : Soil Taxonomy in the Study area 

An area of about 30,169 ha has a clayey texture while the sandy soils cover about 96,420 ha. 

In sandy soil, the production potential is higher because these areas are located in the low 

terraces, which are flat and have a high level of ground water. An overview on the spatial 

distribution of these results has been shown in Figure 4, while more detailed data are 

provided in Table 5. 

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Production potential in the study area 

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Soil Type Soil series Symbol Production Potential Area 

Clayey 30,169 

Alluvium complex AC 15.1-20.0 6,256 

Nakornpanom Nn 13.0-15.0 7,464 

Pimai Pm 15.1-20.0 2,870 

Phen Pn 13.0-15.0 4,871 

Phonpisai Pp 13.0-15.0 8,490 

Ratburi Rb 15.1-20.0 218 

Sandy 96,420 

Korat Kt >20.0 21,683 

Roiet Re 13.0-15.0 33,995 

Sanpaya Sa >20.0 10,307 

Srisongkham Ss 13.0-15.0 22,875 

Sithon St 13.0-15.0 5,490 

Warin Wn >20.0 2,070 

Flooding Area 7,355 

Total Area 133,944 

Table 5 : Area and production potential in Huimong Irrigation Project 

The soil water balance model runs revealed that the water deficit starts from the first decade 

of November in sandy soils, while it starts only in the second decade in clayey soils (Table 

6). 

Decade P ETc STL-1 ETa STL ST.d ETad Water Deficiency 

Jan1 1.52 33.85 2.19 2.2 1.2 3.40 2.19 29.3 

Jan2 1.57 35.86 1.21 1.7 0.8 2.47 1.65 30.3 

Jan3 1.92 23.29 0.82 1.2 1.2 2.35 1.20 30.4 

Feb1 1.67 35.58 1.15 1.7 0.8 2.49 1.65 30.2 

Feb2 3.28 37.14 0.84 2.4 1.1 3.46 2.35 29.3 

Feb3 5.85 21.93 1.11 2.8 3.0 5.79 2.82 26.9 

Mar1 11.72 46.49 2.97 9.4 3.0 12.34 9.36 20.4 

Mar2 14.46 48.40 2.98 11.2 3.3 14.56 11.24 18.2 

Mar3 16.42 32.36 3.32 10.3 6.1 16.45 10.34 16.3 

Apr1 9.03 46.06 6.11 10.1 3.3 13.34 10.08 19.4 

Apr2 15.82 44.42 3.26 11.8 4.1 15.92 11.82 16.8 

Apr3 28.24 28.74 4.10 15.6 11.1 26.69 15.59 6.0 

May1 58.86 39.76 11.10 37.1 21.1 34.31 13.22 0.00 

May2 73.10 36.84 21.09 36.8 42.8 42.77 - - 

May3 83.54 24.06 42.77 24.1 85.0 85.50 - - 

Table 6 : The example of some result of Soil Water Balance calculation 

In table 7, the calculation of the water needs of oil palm in every soil type show that the 

maximum requirements amount to about 438,000 m 3 .ha -1 in sandy soils and to 175,000 

m 3 .ha -1 in clayey soils. 

158


Decade Rainfall ETc S LS SL SCL LC CL C 

Jan1 2 36 34 33 30 27 21 13 3 

Jan2 2 38 36 35 34 32 28 22 16 

Jan3 2 25 22 21 20 19 16 12 6 

Feb1 2 37 36 35 34 33 31 28 24 

Feb2 3 39 35 35 34 33 32 30 27 

Feb3 6 23 16 14 13 12 11 9 7 

Mar1 12 49 36 34 32 31 29 28 26 

Mar2 14 51 36 33 30 29 27 26 24 

Mar3 16 34 15 12 8 6 4 2 0 

Apr1 9 48 39 36 33 31 29 27 26 

Apr2 16 47 30 27 23 22 19 17 16 

Apr3 28 30 - - - - - - - 

May1 59 42 - - - - - - - 

May2 73 39 - - - - - - - 

Oct33 9 20 - - - - - - - 

Nov1 6 31 21 0 0 0 0 0 0 

Nov2 2 31 28 17 0 0 0 0 0 

Nov3 0 20 19 13 0 0 0 0 0 

Dec1 2 32 30 26 14 4 0 0 0 

Dec2 2 30 27 25 17 11 1 0 0 

Dec3 2 22 19 17 12 7 0 0 0 

Total (1000 m 3 ha -1 ) 478 414 334 295 248 215 175 

Table 7 : The comparison of soil water balance in different texture 

PRESENTING AUTHOR 

Somjate Pratummintra*, Senior Expert in Rubber, Department of Agriculture, Ministry of 

Agriculture and Cooperative, Thailand, is an alumnus of Ghent University in 1994. He 

studied Master Degree in the program of Soil Survey and Land Use Planning. After that, he 

got the scholarship from ABOS and He finished Ph.D. in the Twining Program between 

Ghent University and Universiti Putra Malaysia in 2000 in Physical Land Management. 

Email address: spratummin@yahoo.com 

Prof. Dr. Eric .Van Ranst, Department of Geology and Soil Science, Faculty of 

Science, Ghent University. He set the standard template for this work and gave an advisory in 

Land Evaluation Technique and the Yield Gap Analysis. 

Email address: Eric.VanRanst@UGent.be 

Prof. Dr. Hubert .Verplancke, Department of Soil Management and Soil Care, Faculty 

of Bioscience Engineering. He set the template study in soil water balance and gave an 

advisory in Soil physics, and calculating on soil water flux and actual evapo-transpiration 

from Soil Water Balance Equations. 

Email address: Hubert.Verplancke@UGent.be 

Dr. Ann Verdoodt, Department of Geology and Soil Science, Faculty of Science, 

Ghent University. She works in Land Evaluation Technique and the Yield Gap Analysis. 

Email address: ann.verdoodt@UGent.be 

SUMMARY 

The GIS software such as ARCVIEW ver. 3.2 a and remote sensing technique can be applied 

for mapping on an existing area of rubber and oil palm. Land evaluation technique together 

with GIS software could produce a map of production potential of oil palm and rubber. Then, 

159


the result from intercepting both two maps yielded the map of rubber plantation that should 

be substitutes with oil palm base on the crop production. It means that the rubber plantation, 

which a production was lower than 950 kg Ha -1 , should be substituted with oil palm that give 

the production higher than 16 ton FFB Ha -1 year -1 . At last, the same procedures such as 

parametric approach for evaluating the land index of oil palm, a calculation of soil water 

balance were applied to study the area in Northeast Thailand. Then the yield gap analyses 

[20], especially the calculation of soil water balance, can predict a production of oil palm in 

Northeast Thailand for establishing oil palm in this area that will have a production higher 

than 16 ton FFB Ha -1 year -1 . 


The authors wish to express their gratitude to Dr. Somchai Baimuang, Senior Expert, 

Department of Meteorology, who has consistently contributed in making essential 

metrological data available. He also help me to convert each climate data to a digital map. 

Special thanks go to Department of Land Development, furthered contributed in 

providing me all the digital LANDSAT TM 5, and help me to train my colleague for 

analyzing a digital map of land use. 

Special thanks their respective institutions, the Chachoengsao Rubber Research 

Centre, Surat Thani Rubber Research Centre and Surat Thani Oil Palm Research Centre, for 

the generous support staff services during the field survey in their responsibility area. 

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Eighties. E. Pushparajah and P.S.Chew (eds.) vol.2. pp. 343-356. 

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[15]Pratummintra, S., Verplancke, H., Van Ranst, E., Shamshuddin, J., Zauyah, S., Yew, F.K. 2000. Maximum 

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161


SOIL PROPERTIES AND BIOLOGICAL DIVERSITY OF 

UNDISTURBED AND DISTURBED FORESTS IN MT. 

MALINDANG, PHILIPPINES 

Renato D. Boniao 1* , Rosa Villa B. Estoista 2 , Carmelita G. Hansel 2 , Ron de Goede 4 , 

Olga M. Nuneza 3 , Brigida A. Roscom 3 , Sam James 5 , Rhea Amor C. Lumactud 1 , 

Mae Yen O. Poblete 1 and Nonillon Aspe 3 

1 Mindanao State University at Naawan, Naawan, Philippines, 2 Mindanao State University-Marawi, Philippines, 

3 Mindanao State University-Iligan Institute of Technology, Iligan City, Philippines, 4 Wageningen University, 

The Netherlands, 5 Kansas University, USA. 

Abstract 

Mt. Malindang, a natural park in the southern Philippines faces serious problems of 

biodiversity loss and soil degradation. Scarce information on the drastic effects of forest 

cover loss and any form of disturbance keeps the forest denudation and soil loss unabated. 

Therefore, this study was conducted to assess the soil physicochemical and biological 

properties, and the change of such properties with disturbance in Mt Malindang. Undisturbed 

and disturbed forests and agro- and grassland ecosystems of the range, located at altitudes 

above and below the 1000 m asl contourline, were sampled. Results showed that in forest 

areas where human intrusion was less, highest amount of O.M. (20.2%), highest CEC (43 to 

57 cmolc kg -1 soil) and lowest bulk density (0.4 Mg m -3 ) were obtained. The soil was 

relatively fertile. There were also more earthworm species (at least four) in contrast to only 

one species (Pontoscolex corethrurus) in agricultural land and grassland. Activities of living 

organisms (soil respiration rate) in grassland were significantly lower than those of natural 

ecosystems. Root hair plant-feeding nematodes are abundant in all sites except in arable corn 

and grassland below 1000 m asl where semi-endoparasitic species associated with crops 

dominate. Thus, in any human-induced forest disturbance, it is not only the forest cover that 

is lost, but the soil as well. Earthworms and nematodes species composition and a number of 

bio-physicochemical soil properties served well as indicators of this disturbance. 

INTRODUCTION 

Soil is an essential part of the biosphere and is vital for the continued existence of life on 

Earth. It is a crucial component of terrestrial ecosystems and a determinant of their capacity 

to produce goods and services. Unfortunately, despite the role they played in protecting our 

natural ecosystems, the soil and the soil communities and the vital functions they perform are 

still poorly understood. Lack of knowledge on the incredible complexity of soils and the 

organisms that made them their home is probably the singular reason that there is a seemingly 

continued disregard of this vital component of the natural ecosystems. Such a disregard is 

true in the Mt. Malindang range ecosystems, the research site. 

Mt. Malindang range is one of the ecologically valuable areas in Mindanao and is an 

important biodiversity refuge. Yet, the whole range with its varied ecosystems from the 

mossy forest (its highest point) down to the coastal areas is, in fact, ecologically threatened. 

The pressures come from many fronts: subsistence farmers living and encroaching inside the 

Park [5] and farming on steep slopes; logging, either commercial or at small scale, denuding 

the formerly thickly forested lands; and political and economic power holders, and other 

162


interested groups (military or insurgent) [11] within the range who would probably risk a 

fortune just to claim a stake on the land. All these pressures led to soil degradation, followed 

by loss of biodiversity, and the repercussion goes beyond local boundaries. Among people 

dependent on such resources, soil degradation is simply understood as depletion or loss of a 

natural productive resource. Biodiversity and its key function in maintaining the stability of 

(soil) ecosystems are hardly understood [11]. 

Studies, therefore, on soil properties and their relationship to soil biodiversity are expected to 

address the inadequacy of information for conservation needs and for truly sustainable land 

use plans that ultimately protect Mt. Malindang and its natural ecosystems. 

Objectives 

Given the need to save Mt. Malindang Natural Park from the inevitable degradation, the 

study was, therefore, conducted to assess the soil physicochemical and biological properties 

of the range, and to study the changes of such properties with increasing ecosystem 

disturbance. 

REVIEW OF RELATED LITERATURE 

Mt. Malindang is located in the Province of Misamis Occidental, the Philippines. It is a 

watershed and a catchment area. In 1971 it officially proclaimed as a National Park and 

Watershed Reserve through Republic Act 6266. In August 2002, through proclamation No. 

228, the range was proclaimed as Natural Park, which made it, at the same time, a protected 

area. With 78 rivers emerging from the mountain's rugged volcanic landscape [11] and with 

about 15 major catchment basins [5], the range is undeniably the lifeblood of the neighboring 

provinces of Misamis Occidental, Zamboanga del Norte, and Zamboanga del Sur. DENR [5] 

noted that the range or particularly the park is an important biodiversity refuge. Diverse 

endemic faunal and floral species are found in the old-growth and mossy forests, several 

more other species have yet to be identified or discovered. Still others may already be 

threatened or endangered and some may no longer exist. 

The park occupies a total land area of 53,262 hectares, consisting of 24,511 hectares 

forest land, 13,320 hectares shrub lands of open and denuded land and 14,297.25 hectares 

open and cultivated land. The soils are mostly undifferentiated except in the buffer zones and 

down to the lowlands. 

The remaining forest cover, approximately 23,000 ha, has been declining fast 

especially over the last decade, due to some logging and timber poaching activities. 

Eventually, the lush forest is converted to agricultural land and human settlements. Such 

demand for the biological resources has, of course, resulted in high rates of biodiversity loss 

making Mt. Malindang as one of the “hotspots” in the Philippines needing high priority for 

protection and conservation [8]. 

Earthworms, one of the groups of organisms studied, are considered as ecosystem 

engineers. Sensitive to low soil moisture and soil management practices such as soil tillage, 

application of organic matter, pesticides and inorganic fertilizer, the earthworm population 

density tends to increase with increasing organic matter inputs and decrease with soil 

disturbance, e.g., tillage [3]. 

Another group of organisms is the Nematodes. They are microscopic, unsegmented, 

threadlike worms that can be found in soils and sediments of all terrestrial and aquatic 

ecosystems. Nematodes, both free-living and plant-parasitic, possess several attributes that 

make them useful ecological indicators [6]. 

163


Participatory approach 


Series of consultation with the local communities, from the local government units and line 

agencies down to the barangay levels, were conducted during the preparation of the proposed 

study and their participation and commitment to the study and to the eventual conservation 

and protection of the Park, was enlisted. Incorporated in some of these meetings were 

capacity-building trainings, particularly on field sampling, which resulted in developing a 

number of ‘local researchers’. They also became an important source of information in the 

selection of sampling sites. 

Sampling sites and soil sampling 

Sixteen (16) sites (Fig.1) within the Mt. Malindang Protected Area, spread over 8 barangays 

in 4 municipalities, were selected for the study. These sites were grouped according to 

elevation (above and below 1000 m asl) and into four different ecosystems based on the 

degree of disturbance (Table 1). 

In each site at least three plots of 20 x 20 meters were established within which 

composite soil samples were collected for chemical and physical analyses. A sub-sample of 

about 700 g was separated for nematode extraction. The remaining soil (for 

chemical/physical analyses) was air-dried and stored at room temperature. On the same plots, 

3 replicates of an undisturbed sample at 0-10 cm and at 20-30 cm depths, using a core 

sampler with known volume were collected for bulk density. Pits were dug, described and 

sampled for soil classification. The routine physicochemical analyses all follow the standard 

accepted laboratory procedures 

Earthworm sampling and identification 

Within each 20 x 20m plot, 10 subplots measuring 50 cm x 50 cm and 30 cm deep were dug. 

The soil block was put on a plastic sheet and all earthworms present were collected by hand. 

The earthworms were killed in a 70-90% ethanol and stored in 10% formaldehyde and the 

total number and species composition were counted and identified by plot. Species new to 

science were stored for further taxonomic description. 

Soil respiration determination 

In a randomly selected spots of each field plot, soil respiration was measured using the closed 

chamber–Draeger Tube-syringe method described by Parkin and Doran [10]. Each 

measurement was replicated twice. 

Nematode analyses 

Nematodes were extracted from a 100 g fresh weight soil sample stored at 4 o C, using the 

Oostenbrink elutriator technique [9]. Total numbers of nematodes were counted and then 

stored in 4% formaldehyde until identification. Nematodes were identified to family and 

genus level. Next, they were assigned to trophic groups according to Yeates et al. [15]. 

164


Figure 1. Location of Mt. Malindang Protected Area and the sampling sites within four municipalities 

165


Elevation Ecosystems 

Undisturbed 

(Primary) 

> 1000 

masl 

< 1000 

masl 

forest 

Mt. 

Guinlajan 

(6)* 

North Peak 

(6) 

Disturbed Forest 

Small-scale timber extraction: 

a. Mt. Ulo sa Dapitan (6) 

b. Mt. Capole (6) 

c. Old Liboron (3) 

Logged-over- Pongol (3) 

Secondary Growth 

Forest - North Peak (1) 

Small-scale timber extraction: 

Mialen (3) 

Logged-over: Peniel (3) 

Agroforestry: Mamalad (3) 

166 

Agroecosystem 

1 st arable: 

a. Lake Gandawan/ 

Cabbage (3) 

2 nd Arable: 

a. Lake Gandawan- 

Agro (3) 

b. Gandawan - Agro (3) 

Coco 

a. Mialen (3) 

Corn 

a. Bunga (3) 

b. Mamalad (3) 

Grassland 

Lake Duminagat 

(1) 

b. Gandawan 

(2) 

a. Peniel (3) 

Table 1. Sampling sites at different ecosystems in Mt. *Malindang. Numbers in parenthesis are the 

total no. of sampling plots of the site specified 

Soil morphology and classification 


The Mt. Malindang soils were relatively young. Two soil orders, Inceptisols and Entisols 

were reported (Descriptions of 9 profiles not shown). The studied soils, except one Profile 

(Brgy. Peniel), may have andic properties as shown by the bulk density values (Table 2) and 

the nature of the parent material. Such soils have good physical properties and essentially are 

fertile when first cleared for cultivation. However, they deteriorate fast with continued use 

over time, particularly because these soils were concentrated mostly on sloping areas. 

Physico-chemical Properties 

Primary data on the chemical and physical properties of the soils were given in Tables 2 and 

3. It was shown that in a number of parameters, i.e. pH, available phosphorus (P), total 

nitrogen (N), exchangeable potassium (K) and texture, most of the ecosystems studied were 

similar, and if there were any seeming dissimilarities, these were not statistically significant. 

There were, however, soil properties that reflected a higher soil quality in the 

undisturbed ecosystem than in the disturbed ecosystems, such as percent organic matter 

(%O.M.), CEC, and bulk density (Db). 

Organic matter (% O.M.) 

The organic matter contents ranged from 8.5 to 20.2 % (Table 2). These values were 

relatively higher than an ideal soil was supposed to contain [1] and very much higher than 

most of the soils across the Philippines [2]. Comparison of the samples indicated that the 

undisturbed (primary) forests were richer in O.M. than the other ecosystems studied.


ECOSYSTEMS 

BD 

Mg m -3 

OM 

% 

pH 

1:1 H2O 

167 

Avail P 

ppm 

Total 

N % 

Exch K 

cmolc/kg 

soil 

CEC 

cmolc/kg 

soil 

Undisturbed Forest 0.4 a* 20.2 c 4.9 a 2.1 0.5 b 0.2 57.0 c 

Disturbed Forest 0.7 b 15.0 b 5.4 b 1.4 0.5 ab 0.5 40.1 b 

Agroecosystem 0.9 bc 10.3 ab 5.2 ab 1.3 0.4 ab 0.5 27.5 a 

Grassland 1.1 c 8.5 a 5.3 ab 1.0 0.3 a 0.3 23.6 a 

Table 2. Soil chemical properties of the different ecosystems. *Means with same letter are not 

significantly different at 5% level (Duncan) using SPSS 

Among disturbed ecosystems, the amount of O.M. went down with their degree or state of 

disturbance. Comparison by land use types (Table 3), reflecting varying degrees of 

disturbance, confirmed that more O.M. is lost as disturbance progresses into grassland 

(Peniel). Not even reforestation, as was the case of plantation forest in Peniel (6.6 %), can 

raise O.M. content approximately as high as the North Peak level (24.9 %), the undisturbed 

ecosystem. The consequential loss or decline of the natural levels of soil organic matter 

following cultivation is well established in literature. According to Syers and Craswell [12] 

soils under agriculture inevitably show a decline in organic matter because (1) tillage and 

other agricultural practices increase the soil organic matter decomposition rate by mixing the 

surface soil and increasing the number and intensity of wetting and drying cycles; and (2) the 

inputs of plant C are generally less in a disturbed or cultivated system than in natural 

environment. The reduction in return of organic residues to the soil is as much as ten-fold [7]. 

Land Use Types 

OM 

(%) 

pH 

(1:1 

H2O) 

Total 

N% 

Avail P 

ppm 

Exch K 

cmolc/kg soil 

CEC 

cmolc/kg 

soil 

Small scale timber 

extraction 16.0 cd* 5.5 bc 

0.51 abc 1.6 ab 0.54 ab 43.16 d 

Logged-over 11.98 abcd 4.9 ab 0.45 abc 0.8 a 0.18 a 30.96 bcd 

Agroforestry 4.9 a 4.6 a 0.2 a 

0.5 a 0.20 a 20.48 ab 

First arable 14.8 bcd 5.4 bc 0.69 c 

1.9 ab 0.73 b 43.15 d 

Last arable 14.3 bcd 5.4 bc 0.57 bc 

2.6 b 0.28 a 29.77 ab 

Coco 10.6 abc 5.7 c 0.35 ab 

0.5 a 1.16 c 34.87 bc 

Corn 6.6 ab 4.8 ab 0.19 a 

0.5 a 0.30 a 17.14 a 

Grassland 8.5 abc 5.3 bc 0.29 a 

1.0 ab 0.38 a 23.58 abc 

Table 3. Soil chemical properties at different land use types. *Means with same letter are not 

significantly different at 5% level (Duncan) using SPSS 

Cation Exchange Capacity (CEC) 

The CEC values of the ecosystems regardless of elevation were given in Table 2. These 

values were all above the adequate level (20 cmolc kg -1 soil) for plant growth set by the 

BSWM [4]. The undisturbed forest was observed to have the highest CEC value (57.0 cmolc 

kg -1 soil). Grassland, on the other hand, had the lowest CEC (23.6 cmolc kg -1 soil), followed 

by the agricultural and the disturbed forest ecosystems. The CEC difference between 

undisturbed and disturbed forest was quite significant and both had CECs significantly higher 

than those of the agricultural and grassland ecosystems. Obviously, CEC decreases with 

ecosystem disturbance.


Incidentally, ecosystems with high CECs were the ecosystems with high O.M contents. 

Figure 2 shows the trend and the relationship having a high R 2 value (R 2 =0.998). CEC 

coming from humus (O.M.) seemed to play a prominent role. Thus, the importance of organic 

matter to the cation exchange capacity of the soils was once again demonstrated above. The 

organic matter content is in equilibrium with climate, vegetation and other environmental 

conditions. It depletes rapidly if this equilibrium is disturbed by inappropriate management 

practices [13]. It is, therefore, a must that the management of these soils is oriented in 

maintaining sufficient amounts of organic matter. 

CEC (cmolc/kg soil) 

Bulk Density (Db) 

60 

50 

40 

30 

20 

10 

168 

y = 2.8461x - 0.8821 

R 2 = 0.9987 

0 

0 5 10 15 20 25 

% OM 

Figure 2. Relationship between OM and CEC of the different ecosystems 

The bulk densities of the studied soils in each ecosystem were presented in Table 2. The 

values were unusually low for mineral soils, ranging from 0.4 to 1.1 at 0-20 cm depth or 0.43 

– 1.03 Mg m -3 at 20-30 cm (not shown). However, against the backdrop of high O.M. content 

of most soils, these Db values seemed plausible. Mineral particle densities (Dp) usually range 

from 2.5 to 2.8 Mg m -3 , while organic particles are usually less than 1.0 Mg m -3 . Thus, where 

O.M. was observed to be comparatively high, bulk density was also relatively low. 

Undisturbed forest, significantly had the lowest Db value. This was also the ecosystem with 

the highest O.M. Soils in the disturbed ecosystems, grassland and agro ecosystems in 

particular, on the other hand, which may have lost much of their O.M. from human activities 

as presented earlier, had much higher bulk densities. 

Biological components 

Soil Respiration 

Soil respiration values were given in Table 4, all of which were less than the range of 40-72 

CO2-C ha -1 d -1 based on the soil respiration class ratings of Words End Research [14]. Tillage, 

which was known to bring in more oxygen to the soil and expose organic matter to 

organisms, had obviously contributed to the increase of CO2 evolution from the soil. 

Comparatively, although the difference was not statistically significant, the undisturbed 

ecosystem had lower respiration rate than that of the disturbed or agro-ecosystem. The 

grassland ecosystem seemed to be an exception. It had the lowest respiration value among


ecosystems when, in fact, it was the most disturbed albeit quite recently. The reason, maybe, 

was the amount of organic matter available for decomposition. Grassland incidentally (Tables 

2, 3) had the lowest O.M. 

As indicator of biological activity, soil respiration is usually regarded as a positive 

indicator of soil quality. A higher respiration rate results in more nutrients released from 

organic matter and improved soil structure, among others. In this perspective, the agroecosystem 

would have the highest quality soil. High respiration, however, does not always 

indicate good soil quality. It is understood that biological activity is also a direct reflection of 

the degradation of organic C compounds in soil [10]. It indicates loss of carbon from the soil 

system. Viewed from this perspective, the agro-ecosystem in this study must have retained 

less organic matter than the forest ecosystems. Indeed, based on the amount of organic matter 

present in these ecosystems (Table 2) the observation was true. All, except grassland, had 

high O.M. contents and the undisturbed ecosystem had more compared to other ecosystems. 

Earthworms 

Pontoscolex corethrurus, an exotic species introduced from Brazil, was the earthworm type 

that inhabited grassland and agro-ecosystems. It was the only species found in those 

ecosystems. In other ecosystems, varied species, possibly some would be new to science, 

were found. The undisturbed mossy forest had a notably higher number of species per unit 

area than the disturbed forest. Forest ecosystems, disturbed or not, had much more diverse 

species of worms than grasslands and agro-ecosystems (Table 4). In terms of the number of 

individuals, however, the latter two gave the greater numbers at both elevations (below or 

above 1000 masl). The species presence, however, was limited to one, P. corethrurus. It was 

well to note that, in forests, particularly the undisturbed ecosystems, where bigger and more 

colorful species were found, organic matter and surface litters were abundant. This may 

explain why the latter species of earthworms were mostly present. 

Type of 

ecosystem 

Earthworm 

(Ind. per 2.5 m 2 at 

0.30 m depth) 

Earthworm 

(No. of sp per 

2.5m 2 at 0.30 m 

depth) 

169 

Nematode 

(No. of Ind. per 

100 g soil) 

Soil respiration 

(CO2 -C kg ha -1 d - 

1 ) 

Primary forest 9.5 a* 3.8 b 583.3 a 41.34 b 

Disturbed forest 74.6 ab 3.4 b 921.7 a 41.49 b 

Agroeco 113.8 b 1.0 a 910.7 a 

43.16 b 

Grassland 111.0 b 1.0 a 805.0 a 21.59 a 

Table 4. Soil nematode and earthworm abundance and soil respiration in different ecosystems. 

*Means with same letter are not significantly different at 5% level (Duncan) using SPSS. 

Nematodes 

Table 4 showed that the number of individual nematodes per 100 g soil was not 

significantly different among ecosystems and was rather low compared with soils in the 

temperate regions. But when grouped according to feeding habits, plant-feeders came out 

most abundant in all sites studied. And among this group, root-hair feeders dominate except 

in arable corn and grassland below 1000 m asl. In the grassland ecosystem, it was the semiendoparasitic 

group which was abundant in both elevation classes, while the ectoparasitic 

plant-feeding nematodes were most abundant in forest ecosystems at more than 1000 m asl. 

When the relative abundance of nematodes were subjected to principal component analyses


(PCA) with some environmental parameters as passive variables, the result showed that the 

forest ecosystems, located in the upper part of the ordination plot (Fig. 3) and characterized 

by low bulk density, and high organic matter and CEC, have relatively high abundance of 

nematodes. 

Figure 3. PCA of nematodes showing the position of the10 sampling sites (o) and some soil physical 

and chemical properties. 

Further ordination analyses (redundancy analysis, RDA) on the 10 sites with nematode data 

showed that 58% of the variation in the nematode population can be described by the 

environmental variables. In fact, all variables together can explain 84% of the variation 

within the nematode dataset (Table 5). 

Axes 1 2 3 4 Total 

variance 

Eigenvalues 0.305 0.185 0.112 0.072 1.000 

Species-environment correlations 0.993 0.997 0.959 0.929 

Cumulative percentage variance 

of species data 30.5 49.0 60.2 67.4 

of species-environment relation 36.4 58.4 71.7 80.3 

Sum of all eigenvalues 1.000 

Sum of all canonical eigenvalues 0.840 

Table 5. Results of a RDA on the 10 sites with nematode data. Total-N was not included because data 

were missing for two sites; CEC and bulk density were excluded from the analyses because of strong 

autocorrelation with other parameters. 

PRESENTING AUTHOR 

*Renato D. Boniao, Mindanao State University-Naawan, Naawan, Misamis Oriental, 

Philippines. E-mail: rdboniao@msu-naawan.net or natsupm@yahoo.com . 

170


CONCLUSION 

The soil characteristics, both physical and chemical properties, all pointed out that they are at 

their optimum or best levels in ecosystems where human activities occurrence is almost 

absent or none at all. These ecosystems kept the organic matter values high, pH levels 

acceptable and retained relatively good amounts of N or P in the soils. These are also the 

ecosystems that have loamy textural classes and low bulk densities, indicative of good 

structural aggregation, presumably because of, but for one, the high amount of O.M. In 

contrast, forests converted into agricultural lands and later abandoned into grasslands have 

much poorer soil properties. As shown, a good quality of the soil is in part maintained by the 

integrity of the forest cover, and forest or soil disturbance in any form without mitigating 

measures, can ultimately compromise soil quality. As is the case in Mt. Malindang, in time, 

grassland or waste land areas increase while forestlands decrease correspondingly. 

The best way to break the cycle of abandoning old farms and opening new ones is to 

select areas on which, by necessity and social consideration, a certain degree of sustainable 

cultivation is allowable. 

ACKNOWLEDGEMENT 

We wish to thank The Netherlands Ministry of Development (DGIS) for the research 

grant through SEAMEO-SEARCA for the Philippine-Netherlands Biodiversity Research 

for Development in Mindanao: Focus on Mt. Malindang (BRP) 

REFERENCES 

[1] Brady, N.C and R. R. Weil. 1999. The Nature and Properties of Soils. 12 th Ed. Prentice Hall International, 

Inc. 

[2] Badayos, R. B. 1996. Soils and Agriculture in the Philippines. Seminar paper presented at Tsukuba, Ibaraki, 

Japan, October 1996 

[3] Blair, J.M., P.J. Bohlen and D.W. Freckman. 1996. Soil Invertebrates as Indicators of Soil Quality. In: J.W. 

Doran & A.J. Jones (Eds.) Methods for Assessing Soil Quality. SSSA special publication number 49, Madison, 

Wisconsin, USA: 273-287. 

[4] CARE-BSWM. 2002. Soil and Land Resources Evaluation. Mt. Malindang National Park Buffer Zone, 

Province of Misamis Occidental Vol. 1, The Bio-physical Resources. BSWM and CARE Philippines. 

[5] DENR, 1999. Management Strategy for Mt. Malindang. DENR, National Integrated Protected Areas 

Program. p. 22. 

[6] Freckman, D.W. 1988. Bacterivorous nematodes and organic –matter decomposition. Agriculture, 

Ecosystems and Environment 24:195-217. 

[7] Goh, K.M. 1980. Dynamics and Stability of Organic Matter. In: B.K. Theng, (ed), Soils with Variable 

Charge. New Zealand Society of Soil Science. pp 373-393. 

[8] Ong, P.S., L.E. Afuang, and R.G. Rose-Amball (eds). 2002. Philippine Bidiversity Conservation Priorities: 

A Second Iteration of the National Biodiversity Strategy and Action Plan. Department of Environment and 

Natural Resources-Protected Areas and Wildlife Bureau, Conservation International Philippines, Biodiversity 

conservation program. UPCIDS and FPE, Philippines. 

[9] Oostenbrink, M. 1960. Estimating Nematode Populations by Some Selected Methods. In: Sasser J.N. & 

W.R. Jenkins (Eds.) Nematology. Chapel Hill, Univ. N. Carolina Press: 85-102. 

[10] Parkin, T.B. & J.W. Doran. 1996. Field and Laboratory Tests of Soil Respiration. In: J.W. Doran & A.J. 

Jones (Eds.) Methods for assessing soil quality. SSSA special publication number 49, Madison, Wisconsin, 

USA: 231-246. 

[11] SEAMEO-SEARCA. 2002. Biodiversity Research Programme for Development in Mindanao: Focus on Mt 

Malindang. SEAMEO-SEARCA, College, Los Banos, Laguna, Philippines. 

171


[12] Syers, J.K. and E.T. Craswell. 1995. Role of Soil Organic Matter in Sustainable Agricultural Systems. In: 

R.D.B. Lefroy, G.J. Blair and E.T. Craswell (Eds.) Soil Organic Matter Management for Sustainable Agriculture 

A workshop held in Ubon, Thailand, 24-26 August 1994. ACIAR, Canberra. 

[13] Van Wambeke, A. 1992. Soils of the Tropics, Properties and Appraisal. McGraw-Hill, Inc. New York. 

343p. 

[14] Woods End Research. 1997. Guide to Solvita Testing and Managing your Soil. Woods End Research 

Laboratory, Inc., Mt., ME. 

[15] Yeates G.W., T. Bongers, R.G.M. de Goede, D.W. Freckman & S.S. Georgieva, 1993. Feeding Habits in 

Soil Nematode Families and Genera – An Outline for Soil Ecologists. J. Nematology 25: 315-331. 

172


Sub-theme : LAND DEGRADATION : PRESSURES, INDICATORS 

AND RESPONSES 

Various approaches for soil erosion risk assessment 

W. Cornelis, D. Gabriels, H. Verplancke 

Soil Physics and Soil Erosion Unit, Department Soil Management and Soil Care, Ghent University, Gent, 

Belgium 

According to GLASOD (Global Assessment of Degradation), erosion by water and wind is, 

on a global scale, considered as the major cause of soil degradation. The detrimental effects 

of soil erosion are particularly manifest in many tropical rural areas, where farmers are highly 

dependent on the intrinsic land properties and are lacking the means to improve the quality of 

their soils. There is, therefore, an urgent need for policy interventions to arrest soil 

degradation, and erosion in particular, and rehabilitate degraded areas. Erosion risk 

assessment methods offer a vital tool in the planning of such interventions. 

The early erosion models such as the widely adopted USLE (Universal Soil Loss 

Equation) or WEQ (Wind Erosion eQuation) consisted of relatively simple response 

functions that were calibrated to fit a limited number of (regional) observations. Despite our 

progress in understanding soil erosion over the past years and the resulting attempts to 

introduce physically-based deterministic models of varying level of sophistication (e.g. 

WEPP, EUROSEM, WEPS), those ‘good old’ empirical models, though now improved and 

often incorporated into a Geographical Information System, are still very popular and most 

widely used. This was one of the outcomes of the International Symposium on ’25 Years of 

Assessment of Erosion’ held in September 2003 at Ghent University. The empirical models 

have generally a much simpler structure, require less input parameters and show often similar 

performance in terms of prediction accuracy than deterministic models when considering 

yearly averages. Reducing model complexity will generally lead to a minimization of the 

error propagation of erosion models, a topic that should be given much more attention than it 

has now in the future. 

Besides the model-based and strictly quantitative approach, more attention has been 

given in recent years to expert-based methods. These methods use qualitative (categorical) or 

quantitative (numerical) data, or a combination of both, be it in a parametric or nonparametric 

way. An example of a parametric approach is factorial scoring. In this approach, 

scores are given to various indicators of soil erosion and then multiplied giving a combined 

score that represents erosion risk. Non-parametric methods can be based on regression 

techniques such as e.g. kernel density regression or a classification tree. They have the 

advantage that they do not require any assumption about the functional relationships between 

independent (e.g. erosion factor/indicator) and dependent variables (e.g. erosion risk). This, 

however, also implies that the resulting regression is shaped according to the data only, and 

not according to theoretical functions. Expert-based methods in general are further rather 

subjective as they depend on judgment of erosion indicators which can vary substantially 

among experts. Notwithstanding these short-comings, expert-based methods have shown to 

be promising. They are very attractive in those tropical rural areas where numerical data are 

scarce, but where categorical data such as erosion indicators can be relatively easily collected 

by scientists, extensionists or farmers. Integration of the broader scientific knowledge and 

experience of scientists and extensionists with the ‘grass-rooted’ local knowledge can 

become a key factor for successful interventions, and can stimulate the participation of local 

farmers in conservation practices to arrest and combat land degradation. 

173


We finally believe that techniques enabling to identify computer models on the basis 

of expert knowledge of the process of soil erosion, such as e.g. fuzzy methods, should be 

further explored in the context of erosion risk assessment. Fuzzy-based modeling can also 

been applied to improve the empirical or deterministic model-based methods. 

REFERENCES 

[45] W.M. Cornelis, D. Gabriels (eds). “25 Years of Assessment of Erosion”. Catena Special Issue, 64, pp.139- 

364, (2005). 

[46] M. Grimm, R. Jones L. Montanarella. Soil Erosion Risk in Europe. European Soil Bureau. Institute for 

Environment & Sustainability. JRC Ispra. 40 p. (2002). 

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174


INDICATORS AND PARTICIPATORY METHODS FOR 

MONITORING LAND DEGRADATION. A CASE STUDY IN THE 

MIGORI DISTRICT OF KENYA. 

Abstract 

Vincent de Paul Obade 1* , Eva De Clercq 2 

1* United States International University, Nairobi, Kenya, 2 Ghent University, Ghent, Belgium. 

"Knowledge is power" is a common term in development research. The two sides of the same coin, "sharing 

knowledge" and "power sharing", however, lie at the root of problems like desertification and drought. 

Traditionally, farmers have used local knowledge to understand weather and climate patterns in order to make 

decisions about planting and harvesting. This knowledge, which has been passed on from previous generations, 

is adapted to local conditions and has been gained through many decades of experience. The potential of 

identifying the corresponding "grassroots (local) indicators" offers possibilities to design new and more accurate 

approaches to indicators selection, planning and monitoring processes for development. This approach would 

also facilitate local control over the generation and use of knowledge. This paper gives an overview of localgrassroots 

and scientific indicators of land degradation, which could be useful in providing information oriented 

towards reducing poverty and combating desertification in Kenya. The study area is Migori district in Nyanza 

province inhabited mostly by the Luo community of Kenya. 

INTRODUCTION 

Unpredictable rains and long periods without rains may result in crop failure and drought. 

Local people, in response to continuing poverty develop approaches to cope with unfavorable 

environmental conditions. These coping mechanisms can include career change, migrations, 

intensive agriculture etc. To counter drought, the Luo are increasingly applying irrigation in 

addition to using fertilizers and pesticides whenever possible to plant crops like vegetables, 

maize, and sugarcane. Furthermore, the lake region has had a rapid population growth, with a 

13% growth rate [10]. It is not uncommon for the Luo people to have large families of 3-4 

wives and 15-20 children in total. The combinations of all these factors are at the origin of 

land degradation in Migori, Kenya. 

Desertification is "land degradation in arid, semi-arid and dry sub-humid areas resulting 

from various factors, including climatic variations and human activities [8]." Degradation of 

soil, decreasing water resources and changes in the climate are the three main obstacles to 

sustainable agricultural development in Kenya [2, 6, and 7]. The current debate on 

desertification has tended to focus on alarming data and trends in climatology and ecological 

change, to the neglect of the influence of and impact on, social conditions [5]. 

Participatory methods give outsiders a chance to learn how the local people live, what 

signs or signals they look for, and how they sustain their everyday lives. Before the advent of 

modern scientific methods, the local communities in Kenya must have realized that some 

animals, birds, insects and plants had the capacity to monitor and detect the changes in 

climatic conditions. However, research on these techniques continues most commonly to be 

an isolated process. The question then is: if local people's knowledge is to be used for 

monitoring natural resources, how can it be used and how useful and accurate is it for 

decision-makers, planners or implementers? 

175


Objectives 

The objectives of this study are: 

1. Outline and briefly compare various indicators (scientific and grassroots-traditional) and 

the participatory methodologies for monitoring climate, land degradation and land cover 

changes and 

2. Identify indicators perceived by rural communities as affecting their Food Security (FS) 

and the changes (or indicators of change) in the environment that are used by local 

communities to monitor the environmental resources and make decisions about the 

adequacy of their future food supply. 

INDICATORS 

Different approaches to understanding land degradation suggest differences in indicators. 

Scientists' explanations of degradation are derived from conclusions based on scientific data 

sets [2, 3 and 7]. Local perceptions-"grassroots indicators”, on the contrary, are mostly 

derived from the experience gained by the local people from the observable changes on the 

environment over time. This article outlines the factors considered when developing scientific 

and grassroots indicators. 

Scientific Indicators 

Determination of the extent of land degradation can be achieved through the use of 

indicators, including [7 and 9]: topography, soil depth, drainage, nutrient retention, 

vegetation, traffic, level of aluminium toxicity and soil acidity, vertic properties, soil erosion 

potential, flood risk, calcium carbonate, soil salinity etc. Table 1 shows the types of indicators 

and specific factors considered in measuring land degradation [9, 11, and 12]. 

Among the problems facing the development of scientific indicators of land degradation in 

Kenya are: the lack of coordinated data systems between the various stakeholders, poor 

methodologies and inaccuracies in data collection and analysis. As an example one can 

mention the heavy reliance on questionnaires to assess socio-economic conditions, or the 

conflicts in legislation, standards and specifications as given in the “Registration of Titles 

Act” (RTA) of 1919 (Cap. 281), the “Survey Act” of 1923 (Cap.299), and the “Registered 

Lands Act” (RLA) of 1963 (Cap 300) that are used for survey and mapping of land etc. In 

addition, scientific indicators have the weakness of the giving less importance to the effects 

of plant diseases that are soil borne (or perceived to be), as well as pests that live in the soil or 

crop residue. 

176


Physical 

Biological 

Type and subtype of indicator Factors 

Socioeconomic 

Climatic a. Rainfall 

b. Temperature 

c. Rain erosion potential (calculated) 

d. Sunlight duration 

e. Potential evapotranspiration — PET (calculated) 

Soils a. Texture 

b. Fertility (organic matter) 

c. Structure 

d. Permeability 

e. Erosion potential (calculated) 

f. Alkalinization/Salinization 

Topography a. Slope 

Vegetation a. Canopy cover of herbaceous and woody plants (%) 

b. Plant composition and desirable or key species 

c. Potential herbaceous production (calculated) 

Animals a. Animal population estimates and distribution 

b. Herd composition 

c. Herbaceous consumption (calculated) 

Land and water use a. Land use 

b. Water availability and requirements 

Settlement patterns a. Settlements and infrastructure. 

Human biological 

parameters 

a. Population structure and growth rate 

b. Measures of nutritional status and Feeding habits 

Social process parameters a. Conflicts and Migration 

Table 1: shows the scientific parameters considered in land degradation [9, 11 and 12]. 

Grassroots Indicators 

Traditional knowledge is generally defined as the “knowledge of the people of a 

particular area based on their interactions and experiences within that area, their traditions 

and economic systems”. There has been an increasing interest in indigenous knowledge in the 

science of climatology and agriculture [2]. Local climate can be predicted and interpreted by 

locally observed variables and experiences; using combinations of plant, animal, insects and 

astronomical indicators. Table 2 shows grassroots (local) indicators of the people of Migori 

district. In designing grassroots’ indicators, one could ask the elders to explain how they 

predict coming events, rains, etc. What is it that they look for? What enables them to see 

trends? Future possibilities can also be probed by asking questions such as: What happens if 

nothing is done? Or if something is done? The impact of this technique is that most of the 

outsiders and local community end up with some understanding of their land resources, forest 

resources, village boundaries etc. 

177


Issue Indicators Indicator Meaning Expected action by community 

Start of 

rains 

Drought 

Soil types 

and changes 

Flowering and 

shading of 

various 

species of 

plants 

When the Kayongo plant flowers, long rains 

are about to start. The onyiego plant shades 

its leaves and produces fresh buds just 

before the rain. (March and April). The 

modhno plant produces fruit in September 

and turns reddish just before the short rains 

in October-December. 

Bird behaviour The osogo (weaver) birds make noises 

continuously during the day and night, 

Magungu, Ang’etho and Agak fly across the 

sky 

Insect 

behaviour 

Animal and 

human 

behaviour 

Stars, 

Lightening 

and 

Thunderstorms 

Plant and 

animal 

behaviour 

Stars 

Ong’ino, Onyoso and Ngwen insects (ants 

/termites) jump up and down imitating the 

way the women plant with a kwer (farm 

implement), Grasshoppers chirp 

continuously 

Cows and goats jump about excitedly. 

Elders and rain-makers (nganyi) determine 

the coming of rains for example by 

appearance of ayila-plant and gwer-gwer 

birds. Frogs croak. 

Appearance of yugni mammon (the sisters) 

female constellation of stars indicate wet 

season. Rains begin 

Flowering of Otho tree, which usually never 

buds. Mabinju, ochok, and ali plant flowers 

before any other plant. Strong easterly 

winds (Komadhi) marks dry spell. Ober and 

Saye plants shed off their leaves indicating 

drought. Deterioration of the health and 

productivity of crops. 

Appearance of numerous insects which 

destroy crops. Absence of frogs. Snakes and 

other reptiles begin straying into peoples 

houses searching for food. 

Appearance of yugni-machwo (orion).-male 

constellation of stars indicate dry season 

Fertile soils Soil red, heavy and sticky. Insects such as 

ants around anthills, earthworms, snakes 

and rats found here 

Infertile soils Formerly heavy, sticky soil becomes loose 

and coarse. Weeds such as akech, mabinju, 

kayongo grow 

178 

Advanced stages of land preparation and 

manure application. Decisions and 

consultations within households on what to 

plant and where to plant 

Continue land preparation. Preparation of 

seeds 

Continue land preparation. 

Farmers take risk in Planting suitable crops. 

Farmers Plant and Cultivate suitable crops. 

Start storing food. Migrate to empty 

government lands (lop serikal) or employ 

herdsmen, send them with cattle to these 

lands, and check on them frequently; 

(however, those who settle on these lands 

retain previous homes) 

Unthatched rooftops for cattle feed. Sell cattle 

and farms to buy food 

Men migrate to seek employment elsewhere to 

feed families. Women engage more in fish 

business and feed on osuga, awayo, apoth, 

odielo etc Group formations increase, kinship 

affiliations and friendships are strengthened, 

as people grapple with problem of survival. 

Some men run away, leaving wives and 

children behind 

In kitchen gardens where debris and other 

rubbish are thrown away daily, Maize, beans 

and other legumes planted. Sorghum, pigeon 

peas, cowpeas, sweet potatoes and cassava 

planted. 

Manure is added as soil nutrient, crop rotation, 

grow drought resistant crops 

Table 2: Grassroots Indicators of land degradation for Migori district, Kenya.


The weakness of the migori-luo grassroots indicators is that they are subjective in that 

they do not consider the effect of population change, landslides, soil erosion, texture, 

landform type and organic matter content. Furthermore, the appearance of rains is at times 

believed to be influenced by rain-makers, leading to further uncertainty on the reliability of 

the luo indicators. 

HISTORICAL TRENDS 

Historical profiles and time trends are useful in understanding important events or key 

changes between years. As such, they also help to focus on the future in terms of land use, 

climate change, soil erosion, population, tree cover and common property resources etc [1]. 

PARTICIPATORY MAPPING 

Maps are important for communicating land use changes especially where monitoring and 

evaluation are required. The people of the local community can do mapping of the landuse/change 

since they know most about the area under study. Maps are valuable for exploring 

land-use patterns, changes in farming practices, constraints, depletion trends of forest cover, 

land deterioration, water, and crops [9]. The key informants in this process will be the 

elderly, both men and women. The maps can be drawn on paper or on the ground i.e. “onground” 

digitizing whereby maps are sketched on the ground by people of various age 

groups. Secondary data and records can also be brought in for comparative information. As 

postulated by [4], satellite imagery and Global Positioning Systems (GPS) can also be used to 

validate the data. 

CONCLUSION 

In order to improve land management and climate forecasting, the gap between the 

local and scientific indicators needs to be assessed and bridged for the benefit of the rural 

communities who form the largest percentage of the population in Kenya. Neither the 

scientist nor the local-farmer views consider all factors responsible for land degradation. 

There is need for further investigations on grassroots and scientific indicators, to determine 

the most useful soil quality indicators oriented towards sustainable land management. In 

addition, it is important to select indicators that are easy and inexpensive to measure or 

monitor. Identification of grassroots indicators is a complicated process, and there is a need 

for more examination and documentation of this information. Most communities in Kenya 

have their own "grassroots indicators" based on knowledge and practical experience gained 

over time. The indicators differ by area according to environmental conditions and people's 

activities. However, the real challenge will be to evolve hybrid indicator systems bringing 

together the different relevant traditional and scientific, historical and actual perspectives and 

knowledge systems. 

179



I wish to thank Dr-ir. Wim Cornelis and Dr. Ann Verdoodt of Ghent University in Belgium, 

Katsuji Nakamura and Professor Bob Kio Manuel both of the United States International 

University-Africa for their critical comments and contributions towards improving this 

article. I am also grateful to Professors Hubert Verplancke and Eric Van Ranst of Ghent 

University, Belgium for their advice. 

REFERENCES 

[1] Anthony, G.Y., Xia, L. Urban Growth management in the Pearl river delta: an integrated remote sensing 

and GIS approach, ITC Journal 1996-1, pp. 77-86, 1996. 

[2] Coppin, N.J., Richards, I.G. Use of Vegetation in Civil Engineering. CIRIA/ Butterworths, London, 1990. 

[3] De jong, S.M., Paracchini, M.L., Bertolo, F., Folving, S., Megier, J., De Roo, A.P.J. Regional Assessment of 

Soil Erosion using the distributed model SEMMED and remotely sensed data. Catena 37, 291-308, 1999. 

[4] Dymond, J.R., Bẻgue, A., Loseen, D. Monitoring Land at Regional and National Scales and the role of 

remote sensing, ITC Journal 2001-2, pp. 162-175, 2001. 

[5] Evers, Y.D. Dealing with risk and uncertainty in Africa's dry lands: The social dimensions of desertification. 

International Institute of Environment and Development, Issue Paper No. 48, London, UK, 1994. 

[6] GoK (Government of Kenya). Royal Netherlands Government and United Nations Environment Programme. 

National Land Degradation and Mapping in Kenya. United Nations Office, Nairobi, 1997 

[7] Morgan, R.P.C. A Simple approach to soil loss prediction: a revised Morgan-Morgan-Finley model. Catena 

44, 305-322, 2001. 

[8] UNEP. The United Nations Environmental Programme’s (UNEP) Millennium Report on the Environment. 

Global Environment Outlook 2000. Nairobi: UNEP, 1999. 

[9] Van Ranst, E., Verplancke, H. Land Evaluation. Lecture notes. Laboratory of Soil Science, Faculty of 

Science, Ghent University, Belgium, 2003. 

[10] http://www.cbs.go.ke/census1999.html, Accessed online 12 th November 2005. 

[11] http://www.idrc.ca/en/ev-30796-201-1-DO_TOPIC.html, Accessed online 6 th July, 2006. 

[12] http://www.fao.org/ag/agl/agll/lada/emailconf.stm, Accessed online 6 th July, 2006. 

180


Abstract 

PROPOSED PLAN OF ACTION FOR RESEARCH ON 

DESERTIFICATION IN THE SUDAN: 

GEZIRA AND SENNAR STATES 

Kamal Elfadil Fadul and Fawzi Mohamed Salih 

Land and Waterr Research Center, AgriculturalResearch Corporation, Wad Medani. Sudan 

The proposed plan of action for research on desertification in both Gezira and Sennar states includes an overall 

review of the previous and present activities innovated along his aspect. Both protective and preventive 

measures are required to combat desertification. Proper management of the cultivated lands, controlled use of 

the natural forests and rangelands, improvement of the standards of living for the inhabitants and the level of 

awareness pertaining to the problem are all factors of impact on the desertification in both states. Accordingly, 

the proposed plan addresses two experimental sites, one in the natural vegetation zone and the other in the 

irrigated area. The former site involves the cultivation of environmentally adapted plant species, where as the 

latter site caters for the management practices of the crops grown in the cultivated lands. Such a research 

program needs a multidisplinary effort of the specialties concerned together with the provision of funding 

estimated to implementation and follow up. 

INTRODUCTION 

Desertification as a land degradational process is encountered in Sudan at varying levels of 

intensity. It is mostly active in the northern and western regions. Nevertheless, Gezira and 

Sennar states, as parts of the central region, are susceptible to this phenomenon in the near 

future, especially in the northwestern parts of both states. The western part of Gezira state lies 

at he fringes of the degradated area of the northern and western regions, whereas the northwestern 

part of Sennar state borders the tongues of the lighter-textured soils of Managil ridge. 

To illustrate the danger of sand encroachment as a sign of desertification of the northwest 

part of Gezira state, an area of 34 km2 of alluvial clay plain has been invaded and covered by 

sands from the surrounding sand dunes (Fig1). 

However there is hardly any effective research done to monitor or combat the 

approaching danger of desertification. The only effort implemented in this respect was the 

‘Green belt’ of Eucalyptus species grown north of Gezira state and more Mesquit trees east of 

the White Nile at Hashaba area. Previously “Forest” plots existed within the Gezira irrigated 

scheme; also reclamation trials have been carried out in north Gezira salt-affected part 

(Mustafa,H.F., 1998). 

A plan of action has to be drawn for Gezira and Sennar states following an overall 

study of the problem of desertification. Such mode of scientific investigation can be justified 

by threatening of the sand creep from the two bordering directions towards the northern and 

western regions. The increasingly expected hazard of desertification includes even the 

irrigated tracts of lands, save the bare and seasonally rainfed fields, where proper 

management of cultivated crops is envisaged. However this effort requires the collaboration 

of research units, universities, local government and land users as guided and supervised by 

the Desertification and Desert Cultivation Studies Institute in Khartoum University. 

181


11 .438250 

9 .438250 

7 .438250 

5 .438250 

3 .438250 

1 .438250 

-0 .561750 

0 .589750 

The legend 

desertification 

NAME 

Gezira Scheme 

Sand dune 1975 

Sand dune 1985 

Sand duue 1949 

0 .589750 

1 .589750 

1 .589750 

white Nile 

2 .589750 

2 .589750 

3 .589750 

M onitoring of Sand Dune M ovement at North-West Gezira Landsat image for (1985,1975,1949) 

3 .589750 

4 .589750 

4 .589750 

182 

5 .589750 

Scale 1:400,000 ´ 

Fig. 1 : Monitoring of Sand Dune Movement at North-West Gezira Landsat image for (1985, 1975, 

1949) 

5 .589750 

6 .589750 

6 .589750 

7 .589750 

7 .589750 

8 .589750 

8 .589750 

11 .438250 

9 .438250 

7 .438250 

5 .438250 

3 .438250 

1 .438250 

-0 .561750


Objectives 

PLAN OF WORK 

The main objective of this proposed plan of action is to promote the process of combating 

desertification through feasible preventive and protective measures, where a comprehensive 

technological program will be established for the development and management of the agro 

forestry. Specific objectives for Gezira and Sennar states endorse the control measures of 

sand movement along their northwestern fringes by shelterbelts of environmentally adapted 

tree and grass species, the recommended management practices of the cultivated tracts and 

the reclamation of Gezira and low-fertility parts of northwest Sennar. Basic data for both 

states is to be acquired. 

Strategy 

This plan aims at the preservation of the natural ecosystem of Gezira and Sennar states 

including the future projection of the growing population and the diminishing returns of the 

environmental inputs (Purnell,M.F. and Venema,J.H., 1976). 

Priority research themes 

These themes may involve the improvement of degraded cultivated lands (both irrigated and 

rainfed) and the conservation of the susceptible erodable lands (either by water, wind or 

mismanagement). Although all parts of the two states are at stake, still the northwestern parts 

of the Gezira and Sennar states represent priority research areas due to their proximity to the 

invading desert. In addition to these experimental sites, other susceptible parts to 

desertification could be included in the overall plan i.e. Abu Guta, Butana, Tahamid, Rahad, 

Guneid, North-West Sennar and Kenana schemes. 

Research plan 

To set an actual plan of action fulfilling the objectives of combating desertification in Gezira 

and Sennar states, a number of steps have to be considered: 

- Collection of data, including maps of location, hydrology, vegetation, soils and land use. 

Also all relevant literature of research and control efforts is to be compiled as well. 

- Formation of a specialized cadre to review the prevailing biophysical socio-economic and 

political conditions related to the two states. 

- Conducting a comparative study between the past and present situation of the forementioned 

aspects so as to evaluate the magnitude of the problem. 

- Selection of two experimental sites (e.g. north-west of the two states) for planting 

environmentally adapted species. 

- Follow-up of results of the experimental sites prior to the evaluation of the effects of 

control measures applied against the hazard. 

- Monitoring the trend of desertification through time by integrated information system will 

be of high need (using landsat images and/or maps of similar landuse and crop yield 

potentials)(Imad,A.A., etal, 2000). 

- Monitoring of all other aspects of land degradation (e.g. erosion salinization, pollution, 

etc.) for their potential impact on land utilization productivity both in irrigated and rainfed 

areas i.e. by measuring environmental stability index. 

183


- Undertaking a feasibility study prior to the implementation of the research plan for 

provision of necessary funds. Thus a scheduled plan of action is proposed for each state. 

- Inclusion of land dune stabilization as integral activity of the overall research program 

(Table1). 

Activities Area feddans 

1 

1.1 

1.2 

2 

2.1 

3 

3.1 

4 

5 

6 

Two planting (Irrigated & Rainfed) 

Front rows (Laot, Kitir, Turfa, Tundub) 

Back rows (Eucalyptus, Seyal, Sidir, Sunut) 

Ranges: 

Grass-seedlings 

Dune stabilization 

Mesquite and/or Petro-chemicals 

Extension services (T.V, Radio, Leaflets, Seminars, etc) 

Alternative energy sources 

Ohers (Experimentation, Scholarships, Training 

Administration, etc) 

184 

200,000 

200,000 

400,000 

200,000 

Table 1. A scheduled plan of action for each proposed research site in Gezira and Sennar states. 

PROPOSED RESEARCH PROGRAM 

This program aims at establishing comprehensive technologies for the management and 

development of agroforestry. 

Natural vegetation zones 

Acacia seyal (Talh) belt 

This belt lies between 400 to 800 mm isohyets. Experimental sites are selected and reserved 

in agricultural schemes to: 

1. Study and monitor flowering and seeding of Acacia trees. 

2. Specify the critical moisture content necessary for growth (including water conservational 

measures). 

3. Specify methods, rate and timing of planting seeds and young trees. 

4. Specify lateral position of tillers and the suitable time for cutting and activating the trees 

(including natural or agronomic biofactors influencing heir growth). 

5. Specify research site (size 625m 2 ) for data collection, i.e.: 

a) Survey of land use resources, including type and density of vegetation (Van der kevie,W., 

1976). 

b) Comparing local sites with similar international sites (IUFRO). 

c) Correlating product versus factors of production (climate, etc). 

d) Experimenting on agronomic production factors. 

Acacia mellifera (Kitir) belt 

This belt is north of the Talh belt with less than 400 mm isohyets. Experimental sites are 

selected and reserved in agricultural schemes to:


1. Study and monitor flowering and seeding of Acacia trees. 

2. Specify the critical moisture content necessary for growth (including water conservational 

measures). 

3. Specify methods, rate and time of planting seeds and young trees. 

4. Specify lateral position of tillers and the suitable time for cutting and activating the trees 

(including natural or agronomic biofactors influencing their growth). 

5. Specify research site (size 625 cm 2 ) for data collection, i.e.: 

a) Survey of land use resource, including type and density of vegetation (Van der kevie,W., 

1976). 

b) Comparing local sites similar international sites (IUFRO). 

c) Correlating product versus factors of production (climate, etc.). 

d) Experimenting on agronomic production factors. 

Acacia nilotica (Sunut) belt 

This belt lies on both banks of Blue Nile, where, death of old trees due to silting-up in lowlying 

sites and difficulty of regenerating new trees occur. The foreseen activities aim at 

1. Studying the factors affecting silting up. 

2. Estimating the amount of yearly silting up. 

3. Studying the characteristics of soil deposits. 

4. Studying the effect of silting up on establishment of tree roots. 

Irrigation zones 

Eucalyptus plantation 

The foreseen activities include 

1. Genetic improvement of eucalyptus species. 

2. Agronomic studies related to productivity. 

3. Ecological and silvicultural studies as related to productivity. 

Shelterbelts for agricultural schemes 

A shelterbelt model will be made for each scheme. 

Irrigation canals shelterbelts 

The foreseen activities include 

1. Selection of suitable species. 

2. Study of suitable technologies to grow these species. 

Other relevant investigations 

1. The mismanagement of the agricultural schemes (both rainfed or irrigated) leads to 

deterioration of the cultivated lands as reflected by less productivity due to poor 

physiochemical properties of the soils. Such tracts of land may be deserted and hence become 

susceptible to desertification especially after their natural flora has been removed. Also some 

185


of these traces may undergo salinization and/or sodication (e.g. north Gezira, which requires 

reclamation to improve its productivity). 

2. Water harvesting is an important practice in arid areas where the rainwater is collected 

and stored for use during the critical time. Both climate and soils have an effective role in the 

system of water harvesting (Amer,N.M., 1993). The role of climate is through precipitation 

and evapotranspiration (Farah,S.M., etal, 1996). Effective soil factors include texture, depth, 

infiltration rate, water availability, slope and salinity. The study of all these factors (climate 

and soil) will help in the establishment of pasture and forages thus reducing the hazard of 

desertification by vegetation cover and stabilizing the bare land surface. 

3. Some tree species are capable of N-fixation. Such trees may be identified so as to observe 

how much of this nutrient is added to the soil per growing season. 

4. Seed propagation and breeding of selected tree species may be incorporated during the 

research program. 

5. A socio-economic study of all the research program localities may be developed as 

related to the welfare of the people. 

Nevertheless, the implementation of this research plan of action is a multi-disciplinary project 

involving almost all the sectors of the society i.e. government, research centers, universities, 

specialized organizations and the users. 

REFERENCES 

[1] N.M. Amer(1993). "Water harvesting for supplementary irrigation. Regional Seminar on Cereal Production", 

Damascus, Syria, (1993). 

[2] S.M. Farah, I.A. Ali, S. Inanaga. "The role of climate and cultural practices on land degradation and 

desertification with reference to rain-fed agriculture in Sudan". Proceedings of the Fifth Int. Conference on 

Desert Development. Taxas Tch. University, USA, (1996). 

[3] A.A. Imad, M.F. Hassan, A.S. Ahmed. "Importance of information system for progress of research into 

desertification and sustainable development of the natural resources", LWRC, ARC, Medani, Sudan, (2000). 

[4] H.F. Mustafa. "Forestry Research Program During (1998-2000)". Forestry Research Centre, ARC, Sudan, 

(1998). 

[5] M.F. Purnell, J.H. Venema. "Agricultural Potential Regions of Sudan". UNDP project working paper. Soil 

Survey Administration, Medani, Sudan, (1976). 

[6] W. Van der Kevie. "Climatic Zones in the Sudan". Bulletin No. 27, SSA. Wad Medani, Sudan, (1973). 

186


DIAGNOSTIC OF DEGRADATION PROCESSES OF SOILS 

FROM NORTHERN TOGO (WEST AFRICA) AS A TOOL FOR 

SOIL AND WATER MANAGEMENT 

Abstract 

Rosa M Poch*, Josep M Ubalde 

Department of Environment and Soil Sciences, Universitat de Lleida, Catalonia, Spain 

In order to carry out a conservation project in Northern Togo, a survey was conducted to identify soil and water 

degradation processes. The model area occupies 100 ha and is representative of the Savannah Region of 

northern Togo (West Africa). This area belongs to the Centre de Formation Rurale de Tami, where several 

problems due to sheet and gully erosion, overgrazing, waterlogging and trafficability were identified. Parent 

materials are Precambrian granites and gneisses with granodioritic composition. The soil moisture and 

temperature regime are ustic and isohyperthermic respectively (SSS 1999). The vegetation type is a woody 

savannah, with a marked agricultural influence. A soil survey of the model area at a scale 1:5000 (1 observation 

/ 10 ha) showed several mapping units classified as Geric Plinthosol, Orthiplinthic and Arenic Acrisol, Arenic 

Gleysol, Stagnic, Endoeutric Plinthosol (agricultural soils) and Pachic and Gleyic Phaeozem (natural soil) (FAO 

1998). Physical, hydrological, chemical and micromorphological analyses showed that the main problems 

related to the agricultural soils were waterlogging in microdepressions due to saturated flow during the wet 

season, shallowness due to sheet erosion, soil acidity, lack of nutrients and organic matter, and low water 

holding capacities. On the contrary, undisturbed forest soils show very favourable physical and chemical 

properties for root development. The results were used to design soil and water conservation works as drainage 

ditches, zonation of crops and recommendation of management practices for each unit, as well as to assess the 

potential of the soils of the region to improve their quality with appropriate management. The practices are 

recommended not only to improve agricultural production, but also as mechanisms to use soils as carbon sinks 

in the frame of global climatic change policies. 

INTRODUCTION AND OBJECTIVES 

Degradation of soils due to human activity, mainly as soil erosion, is one of the factors 

affecting the future land use of the Savannah region in West Africa. In this region, an 

increase of the population (locally exceeding 300 inhabitants km -2 ) and a decline in the 

agricultural yield has already been recorded [1]. 

The recovery or maintenance of the soil quality requires a diagnostic of the degradation 

processes, and establishing a hierarchy of the soils to manage and the measures to apply in 

order to optimize the economical and human resources. The objectives of this research were 

to carry out the diagnosis of degradation processes through gathering of soil morphological 

and analytical information that are easy to collect, and to assess the type and severity of soil 

degradation and recovering possibilities. 

The physical environment 

MATERIAL AND METHODS 

This work was carried out in a model area of 100 ha located in the Savannah Region of 

northern Togo (West Africa). This area belongs to the Centre de Formation Rurale de Tami, 

187


where peasants of the region are trained on agriculture and husbandry during two years. This 

centre is located 20 km east from Dapaong, the capital of the region. 

The climatic data was taken from a series of 19 years from the meteorological station of 

Dapaong. The climate is sudano-guinean, characterized by a dry season from October to 

April and a rainy season from May to end of September. During January and February a 

strong dusty wind from the NE (harmattan) reinforces the dryness of the season. Annual 

precipitation is 1001 mm, with a maximum in August (266 mm) and a minimum in January 

(0 mm). Interannual variability is high: within the studied series, annual rainfall ranges from 

649 to 1370 mm. The maximum precipitation values in 24 h are 62, 86 and 107 mm for 

recurrence periods of 2, 10 and 100 years. Mean annual temperature is 28.1ºC, ranging from 

25.2 ºC (August) to 31.8 ºC (May). The difference between the average of the maxima (33.6 

ºC) and the average of the minima (22.5 ºC) is higher than the annual variation of the monthly 

mean, characteristic of a iso-temperature regime. Potential evapotranspiration according to 

Thornthwaite is 2057 mm, with a maximum in April (280.8 mm) and a minimum in August 

(106.7 mm). The soil moisture and temperature regime are ustic and isohyperthermic 

respectively [8]. 

Geologically the region belongs to the sedimentary or epimetamorphic cover formations 

from the Voltaian. The study area is found on the birrimian (Precambrian) basement 

consisting on granites and gneiss with granodioritic composition. The rock presents abundant 

large plagioclase crystals slightly oriented. Locally, quartz and pegmatite veins are found [2]. 

The savannah region is characterised by a rolling landscape consisting of sequences of 

platforms, valleys and slopes without precise limits but with a great relevance in soil forming 

and soil erosion processes. These units are found in the model area, at altitudes from 250 to 

270 m asl. 

The vegetation type is a woody savannah, with a marked agricultural influence. The 

dominant species are Parkia biglobosa and Butyrospermum parkii as trees and Acacia 

sieberiana as bush. Riparian and ruderal vegetation are also present. A small remnant of dry 

sudanian forest vegetation consisting of Anogeissus leiocarpus, Butyrospermum parkii, 

Bauhinia thonningii and Ziziphus mauritiaca as main species has been preserved as ‘sacred 

forest’ (fôret sacrée). The main land uses of the region are represented in the study area: 60% 

of the area is devoted to rainfed crops, mainly for self consumption (peanuts, soja, corn, 

sorghum, millet, rice) but also cash crops as cotton, occupying 8% of the area. The rest are 

pastures (30%), forest or abandoned cropland. The crop yields are low due to low fertility of 

the soils and a lack of fertilisation: 1850 kg ha -1 for corn and 1500 kg ha -1 for rice. 

Methods 

The soils of the model area were surveyed at a scale 1:5000 (1 observation/10 ha). Profile 

description was carried out in the main geomorphological and vegetation units previously 

defined. Chemical and physico-chemical characterisation was done in some of the profiles 

according to Porta et al. [5]. 

Tests of infiltration by a double-ring infiltrometer and permeability by the inverse 

Auger-hole method were performed in the main soil units of the study area. 

Three of the profiles were sampled for the micromorphological study. Ten thin sections 

were made according to Guilloré [4] and described following the guidelines of Stoops [6]. 

188


The soils: formation and characteristics 


The soils are developed either on saprolites of igneous rocks, on coarse colluvia of sands and 

petroplinthite gravels. Table 1 presents the main soils related with the geomorphological unit, 

the landuse/vegetation and the parent material. They classify as Ultisols, Vertisols and 

Mollisols, depending on the degree of stability and lack of soil erosion. The morphology and 

micromorphology of the representative soils are found in Table 2 and 3. The soil formation 

processes on the saprolite is fully displayed in Profile 9, who has the most complete sequence 

of horizons. According to this sequence, the alteration of the saprolite consists in the 

weathering of the plagioclases to kaolinite or 2:1 clays, depending on the drainage class of 

the soils. Profile 9 and 7 correspond to a vertic horizon, with frequent slickensides and 

striated b-fabrics. The clay has later been dispersed and illuviated, as it is shown by the 

microlaminated clay coatings in these horizons and in the saprolite itself. Formation of 

plinthic horizons would proceed from the more sandy horizons, with Fe-oxides accumulation, 

either absolute accumulation by direct release from mineral weathering, or residual 

accumulation after clay illuviation. This accumulation is strong enough for an incipient 

cementation in the walls of Profile 9, and is generalized in the platform soils of the region. 

Position 

Tentative classification 

Landuse / Parent material Modal 

FAO 1998 [3] SSS 1999 [8] vegetation 

profile 

Platforms Geric Haplic Plinthustult cotton, corn, Saprolite of syenites and 1,3 

Plinthosol 

peanuts gneiss 

Slopes Upslope Orthiplinthic Plinthic 

soja, corn, Saprolite of syenites and 8 

Acrisol or Kanhaplustult peanuts, gneiss 

Lixisol 

cotton, 

Footslope Arenic Acrisol Arenic 

millet, Colluvium of quartzitic sands 4 

or Lixisol Kanhaplustult sorghum, with petroplinthitic gravels 

Eroded slope Hypereutric Chromic Haplustert pastures Saprolite of syenites and 7 

Vertisol 

gneiss 

Valley Strong Arenic Gleysol Aquic 

Pastures, Colluvium of quartzitic sands 6 

bottoms accumulation 

Quartzipsamment rice with petroplinthitic gravels 

Pachic Pachic Vermustoll Sacred Saprolite of syenites and 5 

Phaeozem 

forest gneiss 

Slight Stagnic, Oxyaquic Argiustoll Pastures, Saprolite of gneiss and sandy 9,2 

accumulation Endoeutric (inc. Oxyaquic rice colluvium on top 

Plinthosol (inc. Haplustoll) 

Gleyic 

Phaeozem) 

Table 1 : Classification, geomorphology and landuse of the soil mapping units in the study area 

The evolution from this model produces different soil patterns depending on the local 

conditions: 

- Soils on stable positions, not disturbed nor cultivated, under a dense vegetation cover 

(Profile 5) undergo an intense OM accumulation. The relatively high base content of the 

saprolite allows even the formation and accumulation of calcite coatings and nodules, caused 

by root and microbial activity. 

- Soils with different degrees of erosion lack this organic-rich top horizon and have sandy 

surface horizons instead, sometimes overlying the plinthic horizon (profiles 1,3). In the most 

severe cases, a slight acidification of the topsoil is proceeding (Profile 1). 

- Redoximorphic features are generalized in the soils of the area, as Fe oxi-hydroxide 

accumulation as concentric nodules, hypocoatings around pores and impregnative nodules, 

either orthic or anorthic. The high permeability of surface horizons in contrast to the 

189

Profile 


impervious vertic or plinthic horizons allows for subsurface saturated flow to occur, which is 

also the cause of erosion of the surface sands which are accumulated on the slopes (Profile 6) 

and in the valley bottoms (Profile 2) 

Horizon 

s 

1 Ap 

Bt1 

Bts2 

Bts3 

2 Apg1 

Ag2 

Bs 

2C 

3C 

3 Ap1 

Ap2 

Bw 

2Bts 

4 Ap1 

Ap2 

Ap3 

Bw 

Bts1 

Bts2 

5 Oa 

Oi 

A1 

Bw1 

Bw2 

Bwg3 

6 Ap 

Bg1 

Bg2 

Bs3 

7 Ap 

2Apg2 

2Bssg 

2Bt 

8 Ap 

Bw1 

Bt1 

Bt2 

9 Apg 

Bg1 

Bst2 

Bsm3 

Bssg4 

C 

Depth (cm) Colour 

(moist) 

0-20 

20-33 

33-55 

55->60 

0-10 

10-25 

25-63 

63-100 

>100 

0-10 

10-19/25 

19/25-40 

40->70 

0-10 

10-20 

20-26/43 

26/43-50 

50-68 

68->90 

-5 - -3 

-3-0 

0-16/19 

16/19-43 

43-75/85 

75/85->90 

0-15/21 

15/21-37 

37-65 

65->80 

0-2 

2-17 

17-35 

35->55 

0-18 

18-33 

33-53 

53->70 

0-20 

20-28 

28-60 

60-73 

73-150 

>150 

7.5YR4/4 

10YR6/3 

7.5YR5/6 

10R4/6 

10YR3/3 

10YR3/3 

10YR4/6 

7.5YR4/6 

- 

5YR2/3 

5YR2/3 

7.5YR4/6 

5YR3/6 

5YR4/6 

5YR4/8 

5YR3/6 

5YR3/6 

5YR4/6 

5YR4/6 

- 

7.5YR1.7/1 

7.5YR2/1 

10YR3/2 

10YR2/3 

10YR4/3 

10YR3/3 

10YR4/6 

10YR5/6 

10YR5/6 

10YR4/6 

2.5Y4/6 

2.5Y6/4 

2.5Y6/5 

7.5YR4/6 

7.5YR4/6 

7.5YR4/6 

10YR5/6 

10YR3/3 

10YR4/6 

10YR6/6 

10YR5/6 

2.5Y6/6 

2.5Y7/2 

Structure 

(primary, 

secondary) 

vw-sab-c 

- 

- 

- 

m-sab-m 

w-sab-m 

- 

- 

- 

vw-c-m 

vw-sab-c 

- 

- 

abs 

abs 

abs 

abs 

abs 

abs 

abs 

abs 

vw-c-m,w-sab-m 

w-sab-c 

m-sab-m 

s-sab-m 

vw-sab-f 

vw-sab-m 

w-sab-m 

- 

abs 

m-sab-m 

s-sab-m 

- 

abs 

abs 

abs 

abs 

w-sab-m 

vw-sab-m 

vw-sab-f 

abs 

vs-sab-f, m-p-c 

parent material 

Texture Coarse 

fragments 

LS 

SL 

SCL 

SCL 

LS 

LS 

CS 

CS 

- 

LS 

CL 

CS 

- 

mS 

mS 

mS 

mS 

CS 

CS 

- 

- 

CS 

CS 

CS 

CS 

LS 

SL 

CS 

CS 

S 

C 

C 

SC 

mS 

LS 

SC 

C 

S 

S 

LS 

– 

C 

- 

16-35% gr 

>70%gr 

>70% 

>70% 

abs 

fr-gr 

vfr-gr 

vfr-gr 

>70% 

fr-gr 

vfr-gr 

ab-gr 

ab-gr 

f-gr 

f-gr 

f-gr 

f-gr 

f-gr 

f-gr 

- 

- 

vf-gr 

vf-gr 

vf-gr 

f-gr 

abs 

f-gr 

f-gr 

>70% gr 

ab-gr 

abs 

abs 

abs 

f-gr 

v-gr 

vf-gr 

f-gr 

fr-gr 

fr-gr 

fr-gr 

vfr-gr 

f-gr 

ab 

190 

Consiste 

nce 

l-vf 

c-fm 

vc 

vc 

vc-fm 

vc-fm 

c-vf 

s 

c 

l-s 

c-f 

c 

vc 

l 

c 

s 

s 

s 

l 

- 

- 

l-vf 

c-vf 

c-f 

c-fm 

l-vf 

l 

c-f 

vc 

l 

vc 

vc 

vc 

l 

c 

c 

vc 

l 

c 

c 

vc 

vc 

vc 

Roots Mottles Accumulations/surfaces Diagnosti 

c horizon 

[3] 

f 

abs 

abs 

abs 

f 

f 

abs 

abs 

abs 

f 

f 

abs 

abs 

f 

f 

abs 

abs 

abs 

abs 

- 

- 

ab 

ab 

ab 

fr 

f 

f 

vf 

abs 

abs 

f 

f 

abs 

f 

f 

vf 

abs 

f 

f 

abs 

abs 

abs 

abs 

abs 

abs 

abs 

abs 

fr-ox 

fr-ox 

ab-ox 

abs 

- 

abs 

abs 

abs 

abs 

abs 

abs 

abs 

abs 

abs 

f-red 

- 

- 

abs 

abs 

abs 

ab-red 

abs 

fr-ox 

ab-ox 

abs 

abs 

fr-ox 

fr-ox 

abs 

abs 

abs 

abs 

abs 

fr-ox 

fr-ox 

abs 

abs 

fr-ox 

abs 

Abs 

silt cutans 

silt cutans, soft iron 

concretions 

silt cutans, soft iron matrix 

Abs 

abs 

iron coatings on coarse 

fragments 

abs 

Abs 

Abs 

abs 

abs 

iron impregnations on soil 

mass 

Abs 

abs 

abs 

abs 

few clay cutans 

few clay cutans 

- 

- 

abs 

abs 

abs 

pressure faces 

abs 

few skeletans on root channels 

few skeletans on root channels 

abs 

abs 

abs 

frequent slickensides 

frequent silt coatings on sands 

abs 

Fe-Mn nodules, soft 

id, silt coatings, vertical cracks 

Fe-Mn nodules 

abs 

abs 

few clay cutans, Fe-Mn 

nodules 

weak Fe cementation 

abundant slickensides 

few silt coatings 

structure: s: strong, m: moderate, w: weak; sab: subangular blocky, g: granular; f: fine, m: medium, c: coarse, vc: very coarse, abundance: abs: 

absent, c: common, fr: frequent, vfr: very frequent, ab: abundant, coarse fragments: gr: gravels, consistence: l: loose, vf: very friable, f: friable, fm: 

firm, s: soft, c: compact: vc: very compact, size f: fine, c: coarse, vc: very coarse, roots: f: few, fr: frequent, ab: abundant, mottles: abs: absent, f: few, 

fr: frequent, ox: oxidation, red: reduction 

Table 2 : Field description of the modal profiles 

ochric 

argic 

plinthic 


mollic 

mollic 

- 

- 

- 

ochric 

ochric 

- 


ochric 

ochric 

- 

- 

argic 

argic 

- 

- 

mollic 

mollic 

mollic 

- 

ochric 

- 

- 

- 

ochric 

ochric 

vertic 

- 

ochric 

- 

argic 

argic 

mollic 

- 

argic 


vertic 

-


Microstructure and porosity Micromass Pedofeatures 

PROFILE 1 Bt1 25-35 cm 

Apedal, vughy, 30%, vughs, 

vesicles, biopores, planar. 

Bts2, 30-40 cm 

Pedal, subangular blocky, very 

coarse sand size. 25%, planar 

voids and vughs 

Bts3, 60-73 cm 

Apedal, vughy, 20%, vughs 

and planar voids 

PROFILE 5 A1, 0-15 cm 

Pedal, granular, coarse sand 

size, well developed. 40%, 

compound packing pores, 

biopores, accomodated planar 

voids 

Bw1, 20-30 cm 

Pedal; Primary: subangular 

blocky, 1 cm, well developed; 

Secondary: channel. 30%, 

planar pores, biopores. 

Bw1, 30-43 cm 

Pedal. Primary: subangular 

blocky, 3 cm, well developed; 


planar voids, biopores. 

Bw2, 50-60 cm 

Pedal, Primary: subangular 

blocky, 4 cm, moderately 

developed; Secondary: 

channel. 30%, planar voids and 

biopores 

PROFILE 9 Ap, 0-13 cm 

Apedal, vughy. 20%, 

vesicules, biopores 

Bst2, 33-43 cm 


blocky (3-4 cm in diameter), 

weakly developed; Secondary: 

vughy; 30%, planar voids, 

vesicles 

Bts2, 43-60 cm 


blocky (1-2 cm in diameter), 

moderately developed; 


planar voids, channels, vughs 

and vesicles. 

Bssg4, 80-85 cm 

Apedal, channel. 20%, vughs 

and vesicles 

Bssg4, 140-155 cm 

Pedal, subangular blocky, 1 cm 

in diameter, moderately 

developed, 20%, planar voids, 

vughs, biopores. 

Brownish mixture of clay and 

silt, mosaic and nodulostriated 

b-fabric 

fe-oxides. 

Intra-aggregate impregations of Fe-oxi-hydroxides, halo, very coarse sand size. 

Few silt and clay intercalations around some vughs, moderately oriented, laminated, mottled. 

Few clay coatings, around fissure walls, limpid, microlaminated, medium sand size, stained with 

Nodules of Fe-oxi-hydroxides, very coarse sand and gravel size, rounded, concentric, with 

inclusions of runiquartz, anorthic, with higher quartz content than the groundmass. 

Id before Nodules of Fe-oxi-hydroxides, very coarse sand and gravel size, rounded, concentric, with 


General impregnation of Fe-oxi-hydroxides, with different degrees of intensity. 

Clay intercalations along walls of planar voids, probably kaolinite 

Id before Clay coatings and infillings around pores, occupying 30% of the soil. 

Nodules of Fe-oxi-hydroxides, very coarse sand and gravel size, rounded, concentric, with 


Orthic nodules of Fe-oxi-hydroxides, aggregate, diffuse, halo, intra-aggregate. 

Dark brown mixture of silt, clay 

and organic pigment, mosaic 

striated b-fabric 

Light brown mixture of silt, and 

clay, mottled; mosaic-, cross- 

and nodulostriated b-fabric 

Yellowish brown mixture of 

clay and silt, grano- and 

porostriated b-fabric 

Yellowish brown mixture of 

clay and silt, mosaic- 

granostriated and slightly cross 

striated b-fabric 

Brownish mixture of clay, silt 

and organic pigment, 

undifferenciated b-fabric, 

locally mosaic striated. 

Yellowish brow mixture of clay 

and silt, mottled, mosaic 

striated b-fabric, locally 

nodulostriated 

Passage features as infilled channels 

Coatings of acicular CaCO3 crystals in some biopores, apparently associated to organic remains. 

Rounded nodules of Fe-oxi-hydroxides. 

Few micritic nodules of CaCO3, medium sand size. 

Concentric nodules of Fe oxi-hydroxides, very coarse sand and gravels, granostriated. 

Few diffuse nodules of Fe oxi-hydroxides, impregnated, orthic, coarse and very coarse sand size. 

Coatings of acicular and microsparitic CaCO3 in some pores 

Passage features as infilled channels 

Coatings of acicular and microsparitic CaCO3 in some pores 

Kaolinite coatings around a planar void and around anorthic nodules 

Nodules of Fe oxi-hydroxides, impregnated, orthic (diffuse) and anorthic, very coarse sand size. 

Impregnations of Fe oxi-hydroxides intra-aggregate, very coarse sand size 

Coatings of acicular CaCO3 in biopores, crystals 0.3 mm long and 0.1 mm thick. 

Impregnative hypocoatings of microsparite in biopores, 0.25 to 0.5 mm in diameter 

Rounded nodules of microsparite, medium sand. 

Microsparite and needles of CaCO3 dispersed in the groundmass. 

Coatings and infillings of mottled clay, microlaminated, colours of 1st and 2nd order, around 

channels, 0.1 to 0.25 mm thick. 

Frequent hypocoatings of Fe oxi-hydroxides, impregnative, around channels 

Rounded nodules of Fe oxi-hydroxides, medium sand, orthic and anorthic 

Frequent intercalations of limpid clay, microlaminated, 1st order colours, up ot 2 mm thick. 

Clay coatings and infillings in channels, < 0.25 mm thick 

Rounded nodules of Fe oxi-hydroxides, with quartz inclusions, sharp boundary. 

Rounded nodules of Fe oxi-hydroxides, impregnative, diffuse boundary. 

Impregnative Fe hypocoatings along channels. 

Id before Rounded nodules of Fe oxi-hydroxides, with quartz inclusions, sharp boundary, very coarse sand, 

granostriated, porous. 

Rounded nodules of Fe oxi-hydroxides, impregnative, diffuse boundary. 

Impregnative Fe hypocoatings along channels 

Clay coatings, infillings and intercalations, limpid, microlaminated, kaolinitic,

Profi 

le 

1 Ap 

Bt1 

Bts2 

Bts3 

2 Apg1 

Ag2 

Bs 

2C 

3C 


Degradation processes 

Soil erosion is one of the main problems, mainly as splash and sheet erosion. The most 

affected soils are those on the platforms and slopes. Soil erosion also occurs by concentrated 

runoff, as rills and gullies. Retreats of 2 m of the gully heads have been observed after a 

single storm event. 

The erosion is due to intense rainfalls during the wet season, low structural stability, 

crops with low coverage and fields with an excessive length with low runoff control. In the 

case of the gullies, saturation flow in the sand colluvia runs along the slopes over the more 

clayey horizons and concentrates at the gully head. The low cohesion of the saturated sands at 

this point is the responsible of the collapse and retreat of the gully heads. 

Regarding the chemical and physical fertility (Table 4), the main problems are the low 

OM contents (600 

>600 

- 

86 

3 18 


Modal profile Infiltration 

capacity (mm h -1 Bulk density of the 

) surface horizon (kg m -3 Permeability class Available water 

) 

capacity AWC (mm) 

1 

100 

1708 

- 

40 

3 

250 

1770 

- 

2 

75 

1418 

- 

48 

9 

60 

1480 

Moderate 

100 

6 

50 

1440 

Slow 

88 

5 100 1195 Moderate 200 

7 60 

1369 

Moderate 

110 

70 

1306 

- 

8 

170 

1612 

Moderate 

94 

4 

320 

1670 

- 

50 

50 

1560 

- 

Table 5 : Hydrological properties of the modal profiles 

CONCLUSIONS 

The results show a very strong influence of human activity in soil formation and distribution. 

Erosion, either geological or human-driven (deforestation, fires) has acted in all soils except 

the undisturbed one under a permanent forest (Profile 5). Its properties show as well a high 

potential quality of the soils of the region, both regarding agricultural yields and also as 

carbon sink in the frame of global change policies. 

The fertility of the most degraded soils cannot be improved significantly unless large 

inputs of organic matter and strict conservation management practices are applied, which are 

not possible given the availability of organic residues and the socio-economical 

characteristics of the region [9]. Instead, the application of good management practices that 

can be adapted to the conventional agricultural systems in the moderately degraded soils -as 

the ultisols-, would optimize the resources, keeping or improving soil quality and leading to 

higher yields. 

In this sense, the management recommendations have been the control of surface runoff 

by a new outline of the fields and a network of contour drainage ditches, the control of gully 

erosion by permeable stone dams, and the management of organic matter: composting, crop 

residue management and bush fences. A new land use redistribution made from soil quality 

and soil erosion maps was also proposed [9]. 


We acknowledge the inconditional help, willigness and enthusiasm of Felipe García (CTFC), 

and the funding of Diputació de Lleida, Proide and Centre de Cooperació Internacional - 

Universitat de Lleida. 

REFERENCES 

[1] P. Brabant, S. Darracq, K Egue, V. Simonneaux. “Togo. État de degradation des terres resultant des activités 

humaines. Notice explicative de la carte des indices de degradation”, Éditions de l’ORSTOM, Paris, 57 pp. 

(1996) 

193


[2] J. Collart, I. Ouassane, J.P. Sylvain. “Notice explicative de la carte géologique à 1/200 000. Feuille 

Dapaong, 1e Édition” Mémoire n. 2. République Togolaise, Ministère de l’Équipement, des Mines et des Postes 

et Télécommunications, DG Mines, Géologie et du Bureau National des Recherches Minières. (1985) 

[3] FAO. "World reference base for soil resources (WRB)", World Soil Resources Report No. 84 , FAO/ 

ISSS/AISS/IBG/ISRIC, Rome, (1998). 

[4] P. Guilloré. “Méthode de fabrication mécanique et en série de lames minces”. CNRS and INA-Paris- 

Grignon. Dep. Sols. Thiverval.Grignon. 22p. (1980) 

[5] J. Porta, M. López-Acevedo, R. Rodríguez. “Laboratori d’Edafologia”. Universitat Politècnica de Catalunya. 

193 pp. (1993) 

[6] G. Stoops. “Guidelines for analysis and description of soil and regolith thin sections”, Soil Science Society 

of America, Madison, Wisconsin. 184 pp. (2003) 

[7] R.M. Rochette. “Le Sahel en lutte contre la desertification: leçons d’expériences”. Weikersheim, Margraf. 

592 pp (1989). 

[8] SSS-Soil Survey Staff. "Soil Taxonomy. A Basic System of Classification for Making and Interpreting Soil 

Surveys ", USDA, Washington. (1999). 

[9] J.M. Ubalde, R.M. Poch. “Projet de conservation des sols et des eaux dans la zone soudano-guinéene au 

Centre de Formation Rurale de Tami (Togo)”, Bulletin du reséau erosion 20, pp 485-495, (2000) 

194


WORKSHOP Theme: Land Evaluation and Land Degradation 

Convenors: A.; Verdoodt, W. Cornelis, E. Van Ranst, H. Verplancke, D. Gabriëls 

CONCLUSIONS 

This workshop focussed on two themes: «Land Evaluation» and «Land Degradation». The 

objectives were (1) to give an overview of the latest developments in both disciplines, (2) to 

review the current activities of our alumni within these fields of expertise and (3) to hold a 

round table discussion on the issues raised, on new research questions and changing needs. 

Although both themes were addressed separately, striking similarities and crosscutting issues 

could be identified throughout the workshop. Both sciences evolved from experimental 

modelling, over process-based modelling, towards more participatory approaches, making 

full use of the local knowledge on land suitability and risks for land degradation. Recent 

research topics in both disciplines focus on identifying soil quality indicators. The research 

topics presented by the 3 alumni illustrated these developments very well. Dr. Pratummintra 

explored the possibilities for oil palm production in Thailand using land suitability 

classification and crop modelling techniques. Dr. Boniao on the other hand, identified bioindicators 

of soil degradation following forest to agricultural land conversion in the 

Philippines; a presentation touching both land evaluation and land degradation issues. And 

finally, within the «Land Degradation» theme, Dr. Poch illustrated how one combats soil 

degradation in Togo making use of soil quality maps and local capacity building. Each 

presentation was followed by a short discussion with the alumni attending the workshop. The 

most important overall conclusion of the workshop was that current methodologies in both 

disciplines integrate – using a sound scientific approach - traditional models building on 

expert knowledge with more recent process-based models and strongly valuable grass-roots 

knowledge. 

195

Workshop IC-PLR 2006 – Theme D – Soil survey and inventory techniques 

WORKSHOP THEME D – SOIL SURVEY AND INVENTORY 

TECHNIQUES 

Sub-theme : Developments in soil (attribute) mapping with a application in 

mapping groundwater depth 

P.A. Finke 

Paper/poster : Using geographic information systems and global 

positioning system to map soil characteristics for land evaluation – P. 

Wandahwa, J.A. Rota, D.O. Sigunga 

Sub-theme : Developments in GIS and remote sensing with emphasis on 

high resolution imagery and 3-D presentation techniques 

R. Goossens 

Paper/poster : Geomorphology and classification of some plaines and 

wadies adjacent to Gabel Elba, South East of Egypt – El-Badawi, M., 

Abdel-Fattah, A. 

Paper/poster : High resolution terrain mapping and visualization of 

channel morphology using Lidar and Ifsar data – Sudhir Raj Shrestha, Dr. 

Scott N. Miller 

Sub-theme : Developments in soil sampling and proximal sensing with 

applications in precision agriculture 

M. Van Meirvenne, U.W.A. Vitharana, L. Cockx 

Paper/poster : Estimating spatial variability of soil salinity using 

cokriging in Bahariya Oasis, Egypt – Kh. M. Darwish, M.M. Kotb, R. Ali 

Paper/poster : Spatial variability of drainage and phosphate retention and 

their inter relationship in soils of the South-Western region of the North 

Island, New Zealand – A. Senarath, A.S. Palmer, R.W. Tillman 

Conclusions 

196


Abstract 

Soil survey and inventory techniques : 

Modern soil survey and inventory techniques have been developed to meet requests for the updating and 

upgrading of soil information systems and to make primary soil inventories in less accessible areas easier. The 

methods have in common that that a soil expectation map is produced by statistical inference methods that 

replace part (not all!) of the field work. Another property is that an assessment of the quality of the soil 

expectation map is produced as well. The latter property is very useful for cost-quality optimization. 

Applications of these new methods are given in the fields of soil map updating and soil inventories for precision 

agriculture. Since digital elevation models play an important role in these new mapping methods, new 

developments concerning the acquisition, availability and presentation of elevation data are summarized. 

Sub-theme : DEVELOPMENTS IN SOIL (ATTRIBUTE) MAPPING 

WITH AN APPLICATION IN MAPING GROUNDWATER DEPTH 

P.A. Finke 

Lab. of Soil Science, Dept. of Geology & Soil Science, Krijgslaan 281, Ghent University, Gent, Belgium, 

Many years of soil mapping has resulted in a wide variety of soil information systems. 

Differences between and also inside countries are found, when the scale, the mapped objects 

and the soil parameters contained in different soil information systems (SIS) are evaluated 

with quality parameters such as completeness, currency and semantic quality. 

The completeness of a soil database is the degree to which the necessary data are 

present. Insufficient completeness can be of geographical nature (incomplete coverage with 

data, insufficient data density) and of thematic nature (insufficiently sampled soil 

parameters). This insufficiency combined with an increasing variety of applications of soil 

information has invoked new soil samplings to upgrade SIS even in areas where the soil 

mapping had long been done [1,7]. 

The currency of a soil database is the degree to which the soil map or the data in the SIS 

are still up-to-date. Thematic soil information that has been reported to loose currency within 

decades after the primary soil mapping are water table depths [3] and carbon contents [5], and 

as a consequence updating programs have been implemented [4]. 

The need to improve the quality of SIS has stimulated the development of new soil 

sampling and soil mapping methods. In general, methods were needed that (1) reduce field 

work, (2) employ existing observational data as well as knowledge about soil formation and 

soil landscape relations. When used for primary soil (attribute) mapping, additionally these 

methods should (3) employ existing soil maps with partial coverage and (4) work in areas 

with scarce soil data. In [6] an overview is given of modern so-called "digital soil mapping" 

methods that meet these requirements. These methods have in common, that they produce a 

soil expectation map (like in the old reconnaissance survey, but now directly at the target map 

scale and map extent), that they use statistical inference methods to replace part of field work, 

and that they in many cases can implicitly assess the quality of the soil expectation map. The 

latter property is very useful for cost-quality optimization. 

One recent example of digital soil mapping was the re-mapping of the water tables in 

the Netherlands [4]. A high reduction of the field work relative to the traditional mapping 

approach was achieved by using a highly detailed DEM and existing thematic maps to 

formalize soil (water)-landscape relations using a combination of stratified multiple 

regression and kriging to obtain maps of various aspects of water table dynamics. All 

197


resulting maps are associated with maps of the quality (prediction error), which allows for 

targeted future improvement. 

REFERENCES 

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education as a decision support system for local land-use officials", Photogrammetric Engineering and Remote 

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I. Survey protocols”. Computers and Electronics in Agriculture, 46, pp. 103-133, (2005). 

[57] D. Devriendt, M. Binard, Y. Cornet, R. Goossens. "Accuracy assessment of an IKONOS derived DSM over 

urban and suburban area", In : Proceedings of the 2005 workshop EARSeL Special Interest Group “3D Remote 

Sensing” - use of the third dimension for remote sensing purposes. 

[58] D. Devriendt, R. Goossens, A. Dewulf, M. Binard. "Improving spatial information extraction for local and 

regional authorities using Very-High-Resolution data – geometric aspects", High Resolution Mapping from 

Space (2003). 

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regional authorities using Very-High-Resolution data - geometrical aspects", In : Proceedings of the 24th 

EARSeL symposium : New Strategies for European Remote Sensing, /May 2004, Dubrovnik, Croatia, pp 421- 

428, (2005). 

[60] P.A. Finke. Updating groundwater table class maps 1:50,000 by statistical methods: an analysis of quality 

versus cost. Geoderma 97: 329-350, (2000). 

[61] P.A. Finke, D.J. Brus, M.F.P. Bierkens, T. Hoogland, M. Knotters, F. de Vries. Mapping ground water 

dynamics using multiple sources of exhaustive high resolution data. Geoderma 123: 23-39, (2004). 

[62] K. Jacobsen. "Analysis of Digital Elevation Models based on space information", New Strategies for 

European Remote Sensing, Rotterdam : Millpress, pp 439-451, (2005). 

[63] K. Jacobsen. "Orthoimages and DEMs by QuickBird and IKONOS", Remote Sensing in Transition, 

Rotterdam, Millpress, 273-279, (2003). 

[64] P.J. Kuikman, W.J.M. de Groot, R.F.A. Hendriks, J. Verhagen, F. de Vries. Stocks of C in soils and 

emissions of CO2 from agricultural soils in The Netherlands. Wageningen, Alterra-report 561. 41 pp. 

(http://www2.alterra.wur.nl/Webdocs/PDFFiles/Alterrarapporten/AlterraRapport561.pdf ), (2003). 

[65] A.B. McBratney, M.L. Mendonca Santos, B. Minasny. “On digital soil mapping” Geoderma, 117, pp. 3– 

52, (2003). 

[66] S.P. McGrath, P. Loveland. The Soil Geochemical Atlas of England and Wales. Blackie Academic and 

Professional, Glasgow, (1992). 

[67] K. Taillieu, R. Goossens, D. Devriendt, A. Dewulf, S. Van Coillie, T. Willems. "Generation of DEMs and 

orthoimages based on non-stereoscopical IKONOS images", New Strategies for European Remote Sensing, 

Rotterdam : Millpress, pp 453-460, (2005). 

[68] T. Vandevoorde, M. Binard, F. Canters, W. De Genst, N. Stephenne, E. Wolff. "Extraction of land use / 

land cover - related information from very high resolution data in urban and suburban areas", Remote Sensing in 

Transition, Rotterdam : Millpress, pp 237-245, (2003). 

[69] G. Zhou, R. Li. "Accuracy evaluation of ground points from IKONOS high-resolution satellite imagery", 

Photogrammetric Engineering and Remote Sensing, 66 (9), 1103-1112, (2000). 

198


USING GEOGRAPHIC INFORMATION SYSTEMS AND GLOBAL 

POSITIONING SYSTEM TO MAP SOIL CHARACTERISTICS 

FOR LAND EVALUATION 

P. Wandahwa 1* J. A. Rota 1 , and D. O. Sigunga 2 

1 Egerton University, Department of Crop and Soil Sciences, P. O. Box 536 Njoro, Kenya. 

2 Maseno University, Department of Horticulture, P. O. Private Bag, Maseno, Kenya 

*Presenting author: Tel: +254-733 26 94 60; Fax +254-51 62527; E-mail: wandahwa2002@yahoo.com 

Abstract 

Land evaluation is traditionally based on conventional soil survey information i.e. the plan-view maps and 

written descriptions in soil reports. The maps consist of soil units that are characterized by a single 

representative soil profile pit on which suitability evaluations are based. The soil unit has single values for all 

soil characteristics analyzed for the profile and the same spatial boundary for these characteristics. These 

implies that soil variability encountered in the process of soil survey is not captured on the resulting soil maps 

and reports, yet analysis of these maps shows that there can be considerable variability in soil properties within 

soil units with consequent variability in land assessment results. In this study, continuous surface maps of 

organic carbon, soil pH, base saturation and soil depth having a value at every location are generated from 

randomly sampled points using geographic information systems and global positioning system. The maps are 

classified on the basis of suitability levels of a test crop, overlaid and the final evaluation results compared with 

those obtained using soil units. The results show that a better distribution of suitability in accordance with the 

random sample points is obtained using these maps than soil units derived from conventional soil survey. 

INTRODUCTION 

The data used for land evaluation have traditionally been derived from conventional soil 

survey maps and reports that range in degree of details from small to large scales. The basic 

premise in soil survey is that soils are predictable along landscape positions. Reliability of the 

predictions is a function of the soil scientists’ abilities to consistently interpret and predict the 

relationship between soils and landscape. The soil scientist does not physically probe every 

acre in the survey area, or use random sampling techniques that allow each member of the 

soil population equal probability of being sampled [12]. 

The maps produced during soil survey are therefore characterized by a modal soil 

profile pit representing a soil unit on which suitability evaluations are based [13]. The soil 

units can be simple map units defined as delineations containing a very low percentage of 

dissimilar soils and conforming to the definition of a single soil type or compound map units 

referring to delineations with a higher percentage of dissimilar soils [19, 25]. Purity standards 

placed on soil map units are therefore a reflection of the expected (interpretative) use of the 

maps and to a degree have misrepresented the true map unit composition. Focus on the soil 

map unit that has undoubtedly served well for the purposes of soil classification, does not 

however produce the best soil database for other applications, thereby weakening the link 

between soil data and process models [14] and hence land evaluation for land use planning. 

An alternative procedure in soil mapping is to focus on point observations that allow 

each member of the soil population equal probability of being sampled and derive continuous 

surface individual characteristic or single factor maps through interpolation techniques. The 

procedure can be used to inventory only soil characteristics required in land evaluation 

thereby reducing the time and costs normally incurred in conventional soil surveys. The 

199


boundaries of individual factor maps are independent of one another and a function of 

interpolation techniques found in Geographic Information Systems (GIS) [27]; therefore free 

from the subjective interpretative abilities of soil scientists. 

Points for interpolation must be geographically referenced using a Global Positioning 

System (GPS) as a prerequisite for management of the spatial information in Geographic 

Information System. The purpose of this study was to generate individual soil characteristic 

maps from randomly sampled points using GIS and GPS and explore their potential for land 

evaluation. Further information on the application of GIS to soil mapping and research can be 

found in publications by Burgess and Webster [4, 5]; Webster and Burgess [28]; Wilding and 

Drees [31]; Trangmar et al. [26]; Webster [30] and Webster and Oliver [29] that represent 

some of the most acknowledged contributions on the subject. 

The Study Area 


The study was conducted in Kakamega District, western Kenya during the month of April 

2001. The District lies between latitudes 0°15' and 1° N and longitudes 34°20' and 35° E in 

the western part of Kenya. It covers approximately 1,486 km 2 . The altitude ranges from 1,250 

m above sea level (asl) in the southwest to 2,000 m asl in the east. Two distinct physiographic 

units evident are the southern hilly belt, and the slightly undulating peneplain, stretching from 

the north to the central and eastern parts. A prominent feature on the eastern border is the 

Nandi escarpment whose main scarp rises from a general elevation of 1,700 to 2,000 m asl 

within one kilometer. 

Annual rainfall in the District varies between 1,000 and 2,400 mm per annum and is 

received as heavy afternoon showers with occasional thunderstorms. About 500 to 1,100 mm 

is received during the first rains (March through June) and 450 to 850 mm during the second 

rains (August through November). Minimum, maximum and mean temperatures range from 

11to16, 24 to 31 and 17 to 23 °C, respectively [11]. 

In this study, soybean was used as a test crop to explore the potential of the 

methodology for land evaluation. During the first rains, 78% of the land is very suitable for 

soybean cultivation because of adequate temperatures and rainfall. Moderate and marginal 

land is 20.6% and 1.4% due to mean temperature of the growing cycle below 20 and 18°C 

respectively. The low temperatures are associated with the high altitude of the Nandi 

escarpment. During the second rains, 9.4% of the land is very suitable while moderate and 

marginal land is 90.5% and 0.1%, respectively. Farmers should therefore be encouraged to 

utilize the long rains season to incorporate soybean in their cropping systems [18]. 

Soils and Landscape Data 

Figure 1 shows the soil map of the study area. The map was prepared by the Fertilizer Use 

Recommendation Project [11] using background information from the Reconnaissance Soil 

Map of the Lake Basin Development Authority at scale 1: 250,000 [2] and the Exploratory 

Soil Map of Kenya at scale 1: 1,000,000 [20]. The soil units are physiographic and 

descriptive in nature without any soil characteristic data. 

200


Soil characteristic 

Fig. 1: Map showing soil units and sample points in the study area 

Suitability class and values 

High Moderate Marginal Unsuitable 

Slope (%) 0-8 8-16 16-30 > 30 

Soil depth (cm) > 75 75-50 50-20 < 20 

Base saturation (%) > 35 35-20 < 20 

pH water 5.6-7.5 5.5-5.4 5.4-5.2 

7.5-7.8 7.8-8.2 

Organic carbon (%) > 1.2 1.2-0.8 < 0.8 

201 

< 5.2 

> 8.2 

Table 1: Soil and landscape requirements for soybean cultivation in Kakamega District (adapted from 

Sys et al., [23] 

Soil characteristic data were obtained from samples collected at 0 to 30 cm and 30 to 60 cm 

depths for 76 randomly selected sites shown in Fig. 1. The sites were geographically 

referenced using a portable Global Positioning System (GPS). Soil depth was determined by 

auguring to 100 cm or impervious layer. Soil drainage and flooding conditions were recorded


at the sites. The collected soil samples were air-dried and the content of organic carbon 

determined according to Okalebo et al. [15], cation exchange capacity (CEC) and basic 

cations (Ca, Mg, K, Na) as described in Sparks [21], and soil reaction (pH) according to 

Anderson and Ingram [1]. Base saturation was determined from the sum of basic cations and 

cation exchange capacity. The values from the two depths sampled were averaged to provide 

the final value for evaluation [24]. 

Soil unit 

code 1 

Unit names [10] 

No. of 

Sample 

points 

202 

OC 2 

% 

Soil 

Depth 

(cm) 

Soil 

pH 

BS 3 

% 

Area 

(ha) 

Slope 

(%) 

UhB3 Cambisol and Ferralsols 2 1.35 100 5.5 18 1434 5-16 

UhB5 Rhodic Ferralsols 1 2.95 100 5.7 41 2435 5-16 

UhD1 Orthic Acrisols 15 1.91 93 5.5 27 19991 5-16 

UhD2 Nito-rhodic Ferralsols 1 1.15 100 5.8 34 135 5-16 

UhDC Acrisols and Ferralsols 2 1.53 90 5.4 20 15225 5-16 

UhG2 Ferralo-humic Acrisols 4 1.24 51 5.9 27 5797 5-16 

UhG5 Humic Acrisols 6 1.74 74 5.6 38 5787 5-16 

UhI2 Luvic Phaeozems 5 2.36 100 5.7 35 6829 5-16 

UhV1 Dystro-mollic Nitisols 2 1.91 100 5.8 24 1845 5-16 

UmD2 Orthic Ferralsols 1 2.42 100 5.6 46 728 2-8 

UmD3 Rhodic Ferralsols 4 2.07 100 5.7 42 3011 2-8 

UmF1 Cambisols and Phaeozems 1 2.14 100 6.6 71 1042 2-8 

UmG2 Ferralo-orthic Acrisols 1 2.14 100 6.6 71 2246 2-8 

UmG3 Chromic Acrisols 13 1.63 97 6.3 54 17532 2-8 

UmG5 Humic Acrisols 16 1.14 82 5.8 30 28017 2-8 

UmG7 Rankers and Cambisols 8 1.18 66 5.6 67 9870 2-8 

UmU2 Ferralsols and Cambisols 1 2.14 100 6.6 71 920 2-8 

UlG3 Acrisols and Lithosols 1 1.92 55 6.1 21 1779 2-8 

UlGC1 Acrisols and Cambisols 4 1.11 63 6.1 26 7548 2-8 

UlX1 Rhodic Ferralsols 1 1.18 100 6.4 20 2878 2-8 

BXC2 Gleysols, planosols etc 1 - - - - 201 0-5 

FUC Ferralsols, Acrisols etc 1 - - - - 1334 2-16 

HGC Regosols, Rankers, etc 1 - - - - 456 16-30 

HU1 Humic Cambisols 1 - - - - 648 16-30 

MU2 Lithosols and Regosols - - - - - 2660 >30 

VXC Gleysols, Vertisols etc - - - - - 8232 - 

1 

The first soil unit letter represents physiographic position as follows: M: mountains and major scarps; H: hills 

and minor scarps; F: footslopes; Uh: upland (upper middle level); Um: uplands (lower middle level); Ul: 

uplands (lower level); B: bottomlands; V: valleys. 

2 

Organic carbon. 

3 

Base saturation. 

Table 2: Soil units shown in Fig.1, number of sample points per unit and their characteristics 

Data Analysis 

Data analysis comprised use of PC Arc / Info [16] followed by IDRISI32 [9] Geographic 

Information Systems. The soil map and sample points were digitized along side other 

physical features in the study area using PC Arc / Info. Vector files for these features were 

created and exported as UNGEN files to IDRISI32. The files were imported and stored in 

IDRISI32 as digital maps for further analysis. Sample points were given numbers to identify 

them and the vector digital map converted to a raster digital map. For each soil characteristic 

(organic carbon, soil pH, base saturation and soil depth), a data file was prepared using the 76


point identifiers and the corresponding characteristic value. The values files were then 

assigned to the digital map having the 76 point identifiers and surface analysis done to 

produce individual characteristic maps in a three step procedure. 

First, the maps were analyzed for spatial dependence in the spatial dependence modeler 

and semivariograms created. Models were then fitted to the semivariograms in the model- 

fitting module. Finally, these models were used to produce continuous surfaces of the 

characteristics using the ordinary kriging method. Ordinary kriging is one of several optimal 

interpolation techniques useful in mapping soil resources [3]. The technique utilizes 

information about the spatial autocorrelation in the vicinity of each sample point to provide 

optimal interpolation between the individual points into continuous surfaces [22]. 

The continuous surfaces of the kriged maps were smoothed and reclassified based on 

suitability class values shown in Table 1 for soybean, a test crop. To evaluate the landscape, 

soil units in Figure 1 were assigned their respective slope values shown in Table 2 and 

reclassified according to suitability slope classes of soybean shown in Table 1. The classified 

soil characteristic maps and the landscape map were overlaid to obtain the final soils and 

landscape suitability map for soybean cultivation based on the most limiting factor. This map 

was then overlaid with maps representing other physical features such as escarpments, 

forests, valleys, roads and towns and the land areas representing these features and different 

suitability levels for soybean cultivation determined. 

Evaluation based on soil units was done by averaging values of soil characteristics 

from a number of sample points within the soil units to obtain a single value for the soil unit 

as shown in Table 2. The total number of sample points for all the soil units was more than 76 

because some fell on boundaries of two soil units and were therefore used for evaluating both 

units. The soil unit value was compared with the requirements for soybean cultivation shown 

in Table 1 and a suitability level assigned to the soil unit. The resultant map was also overlaid 

with maps representing other physical features and land areas representing these features and 

different suitability levels for soybean cultivation determined. 


Random sampling of soil at points geographically referenced using a GPS followed by 

kriging of soil characteristic values in GIS resulted in spatial maps that can be classified for 

land evaluation. Classification of these maps into suitability levels for soybean cultivation 

revealed a better distribution of soil characteristics for organic carbon, soil depth and soil pH 

but not base saturation as shown in Figure 2. The distribution shown by base saturation could 

be an indication that kriging may not be the best statistical tool to use in producing spatial 

maps of this characteristic. On the other hand, it could be an indication of a strong influence 

of soil management practices on base saturation as opposed to the other characteristics. 

Despite the poor distribution exhibited for base saturation, a general indication of soil 

characteristics across the district is directly observed and users of this information do not 

have to glean written descriptions in a separate location as in the case of conventional soil 

survey maps [8]. 

A close look at the characteristic maps reveals that soils in the district are generally 

shallow and poor in fertility. Forty two percent of the district has soil pH equal to or less than 

5.5, while 54% has organic carbon equal to or less than 1.2%. Sixty two percent of the district 

has base saturation equal to or less than 35%, while 59% has soil depth equal to or less than 

0.75 m. The maps can be used to identify areas with soil problems that require to be 

addressed. 

203


Organic carbon Soil depth 

pH Base saturation 

Suitability level 

Fig. 2: Maps showing soil characteristics and their level of suitability to soybean cultivation 

204


Table 3 shows results of the final evaluation based on soil characteristic maps and the 

soil unit map. In the study area, 17.6% of the district is accounted for by valleys, escarpments 

and forests. Evaluation based on soil characteristic maps reveal that very suitable soil is 

found in 3.5% of the district, while moderate and marginal soil is found in 38.5% and 38.6% 

of the district, respectively. Unsuitable soil owing to low soil pH is found in 1.8% of the 

district. On the basis of soil units, highly suitable, moderate and marginal soil is found in 

5.8%, 72.7% and 3.9% of the district, respectively. There is no unsuitable land when soil 

units are used for evaluation yet sample point data shows sites that are classified as unsuitable 

due to low soil pH values. 

Soil characteristic maps Soil units 

Suitability level Area (ha) (%) Area (ha) (%) 

High 5131 3.5 8,609 5.8 

Moderate 57,266 38.5 108,024 72.7 

Marginal 57,341 38.6 5,830 3.9 

Unsuitable 2,725 1.8 0 0 

Valleys 8,232 5.5 8,232 5.5 

Escarpment 2,660 1.8 2,660 1.8 

Forests 15,225 10.3 15,225 10.3 

Total 148580 100 148,580 100 

Table 3: Land evaluation for soybean cultivation based upon soil characteristic and soil unit maps of 

Kakamega District 

When soil characteristic maps are used for evaluation of soil suitability, the amount of 

land delineated as having moderate soil (38.5%) is similar to that indicated as having 

marginal soil (38.6%) to soybean cultivation. However, on the basis of soil units, the amount 

of land delineated as having moderate soil (72.7%) is by far more than that delineated as 

having marginal soil (3.9%) to soybean cultivation. The reason is that large tracts of land are 

delineated under single soil units and evaluated using one value obtained by averaging a 

number of sample point values as shown in Table 2. This is the same way representative soil 

profiles from conventional soil survey maps are used to evaluate soil units. 

By randomly sampling points geo-referenced using a GPS and utilizing interpolation 

techniques in GIS, it was possible to create continuous surface maps for individual soil 

characteristics and use them to produce soil evaluation maps for soybean production in the 

study area. Interpolation techniques have been used to create factor maps for evaluation of 

suitable areas for crops even when detailed soil survey information was available [6, 7]. This 

is an indication that the procedures provide more information than is otherwise captured in 

conventional soil survey maps and reports. 

CONCLUSIONS 

The present study successfully demonstrates the potential of using a GPS and GIS for land 

evaluation. Random soil characteristic data however respond differently when subjected to 

interpolation techniques during the development of soil characteristic maps. There is need for 

further research on the type of interpolation techniques suitable for mapping soil 

characteristics. Soil characteristic maps show spatial variations of these characteristics and 

are therefore useful in locating soil related problems. Soil variability not captured in 

205


conventional soil survey maps is captured in soil characteristic maps developed using 

interpolation techniques. The maps can be used for spatial modeling of soil processes. 


The authors acknowledge the financial support for this study provided by the African Career 

Award (ACA) program of the Rockefeller Foundation. 

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[10] FAO. “Soil map of the world. 1: 5,000,000, volume 1 legend”. FAO/UNESCO, pp. 59, (1974). 

[11] FURP. “Fertilizer use recommendation project: Kakamega District”. Vol. 7, KARI, Nairobi, Kenya, (1987). 

[12] S.L. Hartung, S.A. Scheinost, R.J. Ahrens. “Scientific methodology of the National Cooperative Soil 

Survey”. In: Spatial variability of soils and landforms, M.J. Mausbach, L.P. Wilding (eds). SSSA Special 

Publication Number 28. Soil Science Society of America, Inc. Madison, Wisconsin, USA, pp. 39-48, (1991). 

[13] D.N. Kimaro, B.M. Msanya, G.G. Kimbi, M. Kilasara, J.A. Deckers, E.P. Kileo, S.B. Mwango. 

“Computer-captured expert knowledge for land evaluation of mountainous areas: A case study of Uluguru 

Mountains, Morogoro, Tanzania”. UNISWA Research Journal of Agriculture Science and Technology 6 (2), pp. 

120-127, (2003). 

[14] D. Lammers, M.G. Johnson. “Soil mapping concepts for environmental assessment”. In: Spatial variability 

of soils and landforms, M. J. Mausbach, P.L. Wilding (eds). SSSA Special Publication Number 28. Soil Science 

Society of America, Inc. Madison, Wisconsin, USA, pp. 149-160, (1991). 

[15] J.R. Okalebo, K.W. Gathua , P.L. Woomer. “Laboratory methods of soil and plant analysis: A working 

manual”. Soil Science Society of East Africa, Nairobi, pp. 128, (2002). 

[16] PC Arc / Info. “Users guide version 6.1”. Environmental Systems Research Institute (ESRI), Inc., 

Redlands, CA, USA, (1992). 

[18] J.A. Rota, P. Wandahwa, D.O. Sigunga. “Land evaluation for soybean (Glycine max L. Merrill) production 

based on kriging soil and climate parameters for the Kakamega District, Kenya”. Journal of Agronomy, 5(1), pp. 

142-150, (2006). 

[19] W. Siderius. “Standards for soil surveys in Kenya”. National Agricultural Laboratories, Nairobi pp. 13, 

(1980). 

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[20] W.G. Sombroek, H.M.H. Braun, B.J.A. van der Pauw. “Exploratory Soil Map and Agro-climatic Zone Map 

of Kenya, scale 1: 1,000,000”. Exploratory Soil Survey Report No. E1, Kenya Soil Survey, Nairobi, pp. 56, 

(1982). 

[21] D.L. Sparks. “Methods of Soil Analysis. Part 3: Chemical Methods”. SSSA Book Series, 5. SSSA and 

ASA, Wisconsin, U.S.A, pp. 1390, (1996). 

[22] A. Stein, C. Ettema. “An overview of spatial sampling procedures and experimental design of spatial 

studies for ecosystem comparisons”. Agriculture Ecosystem and Environment 94, pp. 31- 47, (2003). 

[23] C. Sys, E van Ranst, J. Debaveye, F. Beernaert. “Land Evaluation part III: Crop requirements”. 

Agricultural publication No. 7. GADC, Brussels, Belgium, pp. 197, (1993). 

[24] C. Sys, E. van Ranst, J. Debaveye. “Land Evaluation part II: Methods in Land Evaluation. Agricultural 

publication No. 7. GADC, Brussels, Belgium pp: 274, (1991). 

[25] N.H. Taylor, I.J. Pohlen. “Soil survey method: a New Zealand handbook for the field study of soils”. New 

Zealand Soil Bureau Bulletin 25, DSIR, Wellington, (1970). 

[26] B.B. Trangmar, R.S. Yost, G. Uehara. “Application of geostatistics to spatial studies of soil properties”. 

Adv. Agron. 38, pp. 45-94, (1985). 

[27] D.R. Upchurch, W.J. Edmonds. “Statistical procedures for specific objectives”. In: Spatial variability of 

soils and landforms, M.J. Mausbach, L.P. Wilding (eds). SSSA Special Publication Number 28. Soil Science 

Society of America, Inc. Madison, Wisconsin, USA, pp. 49-71, (1991). 

[28] R. Webster, T.M. Burgess. “Optimal interpolation and isarithmic mapping of soil properties III. Changing 

drift and universal kriging”. J. Soil Sci. 31, pp. 505-525, (1980). 

[29] R. Webster, M. Oliver. “Statistical methods in soil and land resource survey”. Oxford Univ. Press, Oxford, 

United Kingdom, (1990). 

[30] R. Webster, “Quantitative spatial analysis of soil in the field”. In B. A. Steward (ed.), Advances in soil 

science 3. Springer – Verlag, New York, pp. 1-70, (1985). 

[31] L.P. Wilding, L.R. Drees. “Spatial variability and pedology”. In: L.P. Wilding et al. (ed.). Pedogenesis and 

soil taxonomy I. Concepts and interactions. Elsevier, New York, pp. 83-116, (1983). 

207


Sub-theme : DEVELOPMENTS IN GIS AND REMOTE 

SENSING WITH EMPHASIS ON HIGH RESOLUTION IMAGERY 

AND 3-D PRESENTATION TECHNIQUES 

R. Goossens 

Dept. of Geography, Krijgslaan 281, Ghent University, Gent, Belgium. 

Since the year 2000 Remote Sensing is undergoing a drastic change, offering much more 

possibilities than the decades before. These changes can be summarised as follow: 

- Very High Resolution imagery (VHR), 

- Stereo vision at different resolutions, 

- Digital photogrammetry, 

- Super to hyper spectral imagery. 

The VHR images are recorded mainly with the satellites IKONOS and Quick Bird. 

Both satellites are comparable concerning the spectral characteristics, they are recording the 

blue, green red and near infra red light, allowing image analysis in the visual as well as the 

infra red light. True as well as false colour composites can be created, and image 

classification can be performed based upon 4 spectral bands. The main characteristics of 

these sensors are their ground resolution; IKONOS has a ground resolution of 4 meters in the 

multi spectral mode (XS) and 1 meter in the panchromatic (P) mode while Quick Bird has 

2.44 meter in the XS mode and 0.61 meter in the P-mode. 

Also other sensors provide stereo imagery at medium resolution. The ASTER sensor is 

an excellent tool for the creation of DEM, ortho-photo maps and contour maps. Where in the 

past topographical information at an appropriate scale was a problem, this problem can easily 

overcome with the ASTER sensor in combination with GPS technology. 

Both new types of sensors came available on the moment that also photogrammetry 

became digital. The combination of both events makes it now possible that topographical 

information is easy to be created. With a minimum of 6 ground control points, areas of 60 by 

60 km can easily be mapped in an automated way. In the frame of soil survey, information on 

slope and aspect is crucial. It will be discussed how DEM are generated in an automated way. 

An other trend in remote sensing is the shift from multi-spectral imagery towards super- 

and hyper-spectral imagery. The Aster sensor has 16 bands available in the visual, near 

infrared, short wave infrared and the thermal range. This allows a more detailed mapping of 

the soil material. A Belgian satellite, called Chris-Proba, is taken super spectral images with 

32 bands, with the possibility of stereo viewing. This satellite and sensor summarize the 

possibilities of future remote sensing. 

Also more and more imagery is coming available free of charge or at minimum cost. 

During the seminar all possibilities of obtaining imagery will be discussed and listed. 

REFERENCES 






208











Space (2003). 




428, (2005). 













52, (2003). 



[84] K. Taillieu, R. Goossens, D. Devriendt, A. Dewulf, S. Van Coillie, T. Willems. "Generation of DEMs and 

orthoimages based on non-stereoscopical IKONOS images", New Strategies for European Remote Sensing, 





[86] G. Zhou, R. Li. "Accuracy evaluation of ground points from IKONOS high-resolution satellite imagery", 

Photogrammetric Engineering and Remote Sensing, 66 (9), 1103-1112, (2000). 

209


GEOMORPHOLOGY AND CLASSIFICATION OF SOME 

PLAINES AND WADIES ADJACENT TO GABEL ELBA, SOUTH 

EAST OF EGYPT. 

Abstract 

El-Badawi, M. and Abdel-Fattah, A. 

National Research Center, Soil dept., Cairo, Egypt. 

The area under investigation is located in the southern eastern part of Egypt (Gabel Elba). It is considered as a 

promising part for the urban extension by establishing new communities due to the abundance of the natural 

resources. 

The current work used the remote sensing tools for preparing a geomorphological and soil maps based on the 

delineating of the photomorphic units (PMU`s) according to the visual perception (visual interpretation). The 

image classification is based upon the photomorphic elements, which can be easily distinguished. Their values 

are combined to define the PMU`s. Ten photomorphic units were recognized namely, Delta plain, Alluvial plain, 

Wadi, Sand dunes, Beach, Sabkhas, Costal plain, Plain with rock out crop, Denuded hill and Mountain. 

According to the USDA soil taxonomy (1998), the data showed that the soils belong to Entisolos and Aridisolos 

orders. These orders could be classified into six sub great groups: namely, Typic Torrifluvents, Typic 

Quartzpssaments, Typic Torripssaments, Typic Haplosalids, Typic Petrocalcids and Typic salorthids. 

The study has produced geomorphological and soil maps of scale 1:100000 based on remote sensing (Landsat 

TM) accomplished with the field observation and laboratory analysis. 

Key words: soils, south east Egypt, remote sensing, visual interpretation, soil taxonomy. 

INTRODUCTION 

The total area of Egypt is about one million square kilometers. It consists of about 94% desert 

and 6% as a traditional agricultural land of the Nile delta and valley. Therefor, there is a 

severe pressure and demand dictated by the growing population on this limited area of 

agricultural land. 

Rehabilitating and developing the south eastern part of Egypt are among the major 

aims of the government. Hence, this study may be regarded as a base for a better 

understanding of the soil characteristics and soil classification of these areas. 

The current work has been performed by applying a false color composite landast TM 

image as suitable tools to define the main soil mapping units by the recognition of the 

geomorphological units and the field observation. Eventually, the geomorphological 

characteristics and the soil classification of the different features adjacent to Gabel Elba 

would be performed. 

PHYSIOGRAPHIC FEATURES 

The area under investigation occupies the extreme south eastern part of Egypt. It is bounded 

by 36°00` and 36°30` east and 22°30` and 22°00` north fig(1). 

It has torric and hyperthermic moisture and temperature regimes. The mean annual 

rainfall is 6.5 mm, mainly falling in winter and the mean maximum temperature is 29.71 °C 

210


mainly in summer. The area is exposed to north – eastern and south - western winds with a 

mean velocity of about >21 Knots. 

Egyptian Geological Survey and Mining Authority Staff (1981)[6], Egyptian General 

Petroleum Cooperation Staff (1987) [5], Said (1990) [15] and El-Rakaiby et al. (1996) [13] 

indicated that the surface of (Halaib-Shalatin) region is occupied by about fourteen rock 

formations belong to Precambrian, Cretaceous, Miocene and Quaternary ages 

Abu Al-Ezz, (1987) [13], Hammad (1994) [7], Desert research center (1994) [4] stated that 

two main geomorphic units are recognized; 

a) Basement ridges which occupy most of the surface area around 13000Km 2 ; (78% of the 

total area). It is formed by fractured hard igneous and metamorphic rocks, having an 

elevation ranging between 1000-1900 m a.s.l. the ridges are considered as the main watershed 

area. The surface is severely dissected by many wadis tributaries. 

b) The coastal plains represent a continuous strip of low lands bordered from north to south 

by the Red Sea, at altitude rarely exceeding 100 m a.s.l. The width varies greatly (5-30 Km) 

and the largest width is found at Diìb`s delta Fig (1). It occupies an area of about 3700 Km2, 

represents about 22% of the total area. It includes different landforms, namely; sabkha, 

alluvial fans, and shallow wadis mostly perpendicular to the coast. 

The following methods have been used: 

1- Visual interpretation 

Fig 1: location of the study area 


Landsat TM image acquired on path 72 and row 44/45 in 19-7-1995 was used. The 

interpretation was done on a false color composite of bands 2, 4 and 7 at scale 1:100000 fig 

(2). The major landforms were identified by the physiognomic analysis, Bennema and 

Gelens, (1969) [10] . 

The landast image was carefully analyzed to demonstrate easily the distinguishable 

physiographic features and land cover. Among the image characteristics, the following 

elements have been used; shape, size, color tone, texture and pattern recognition. 

The image interpretation was based on the following criteria; soil surface, slope relief, 

drainage patterns, vegetation etc. Vink, (1963) [1] . 

211


Geological map at scale 1:500000 and topographic map at scale 1:100000 were used to guide 

the image interpretation. 

2- Field work and laboratory studies 

The field work was undertaken to verify the established soil mapping units, which were 

represented by ten soil profiles fig (3). A detailed morphological description was performed 

according to the guide lines FAO (1970) [8] ,Table (3). Thirty soil samples were collected and 

subjected to the following analysis: 

1- Particle size distribution was carried out by dry sieving as described by Black (1985) [2] . 

2- Calcium Carbonate by the Collin`s Calcimeter methods (Piper, 1950) [3] . 

3- Soluble salts in the saturated soil extract, soil reaction in the soil paste, cation exchange 

capacity and gypsum percentage were determined according to the standard methods by 

Richards (1964) [11] . 

4- Organic matter was determined by the method of Walkely and Black (Jackson, 1973) [12] . 

5- Soil classification was carried out according to the USDA soil taxonomy (1998) [16] . 

1. Visual interpretation 


The best color combination for the recognition of soil and water bodies has been the 

enhanced FCC of bands, 2 (visible green) as blue, 4 (NIR) as green and 7 (MIR) as red. The 

FCC was projected on a transparent screen at scale of 1:100 000 for image interpretation. 

Based on the interpretation elements and the knowledge drawn from other sources (i.e. 

geological map, topographical map and the field work); eleven photomorphic units could be 

delineated and discussed. fig (2) and table (1) 

Image characteristics 

Group Geomorphic unit 

color texture pattern 

Nature of 

the pattern 

1 Water Very dark blue F No X 

2 Delta plain Mixed colors F to M P Y 

3 Alluvial plain Light to dark G F P X 

4 Wadi W - Grey F to M L X 

5 Sand dunes W / Y M to F L X 

6 Beach Y (W) F No X 

7 Sabkhas 

Light to dark 

B(W) 

F to M P Y 

8 Costal plain Very pale G F to M No Y 

9 

Plain with rock out 

Mixed colors F to M No Y 

crop 

10 Denuded hill Dark G M to C Pol to P Y 

11 Mountain Light to dark G C pol X 

Table 1: Image characteristics of the mapped pmu`s 

212


Group 1 

This PMU was the easiest unit to be interpreted, since it shows nearly the same color of water 

bodies. The dominant and the only color of the PMU is very dark blue. The unit has a fine 

homogenous texture and no pattern has been detected. 

The color characteristics of the PMU is coinciding with the water bodies i.e. the red sea 

and the water logged area. 

Group (2): 

This PMU appears in various color (light green, pinky and dark green color) and refers to the 

out-wash of the mountain, fine to coarse in texture. Since the coarse materials precipitate first 

and the fine materials come at the end of the precipitation, the unit takes a delta shape. 

Group (3): 

This PMU refers to the alluvial plains, founded in the out-wash area and having a very fine 

materials. 

Group (4): 

This PMU refers to the wadies having many drainage patterns. 

Group (5): 

This PMU exists in the north west of the study area, it displays as an accumulation area of 

wind blown sand in longitudinal shape. The desert pavement and the gravelly corridors 

between the dunes appear in a pale pink and greenish color. 

Group (6): 

The yellowish and the whitish colors indicate a high reflection through out the wavelength 

range of the spectral bands; referring to the landscape features of fine homogenous texture 

and the smoothness of the surface. According to the color characteristics and the patterns; this 

PMU has been interpreted as beach. 

Group (7): 

This PMU has been interpreted as sabkhas and could be divided into wet and dry. The blue 

color refers to the presence of water, 

Group (8): 

According to image interpretation and the field observation, the PMU has been referred to the 

costal plain. 

Group (9): 

This PMU has mixed colors of light green, pale yellow and pale green with inclusion of 

white. It is covered by gravelly and stony materials transported by water stream. The PMU 

has been interpreted as plain with rock out crop. 

213


Group (10): 

The distribution of this unit inside the macro PMU, is homogenous. In few cases a relation 

was found with the hydrographic network. It refers to the strongly exposed rock out crop and 

interpreted as denuded hill. 

Group (11): 

This PMU refers to Mountain 

2. Field trip 

According to the differences in the photomorphic unit (preliminary classification) the sample 

areas were chosen and ten soil profiles have been described and sampled, Fig (3). 

3. Final classification map 

The final delineation of the geomorphic units was based on the image characteristics and the 

field observation. Fig (2), table (2) Each geomorphic unit was described as following:- 

1. Sabkhas 

The total area of this unit is about 8.6 Km2 (2064 feddan) and represented by profile 4. The 

soil surface slopes towards the sea. The soils are originated from alluvial deposits mixed with 

marine deposits. The surface is covered with shells, some low hummocks and few scattered 

vegetation mainly from halophytes. 

The profile depth is varied from shallow to deep as far from the sea. The fine texture is 

dominated while the gravel content is varied from layer to another; it is 17.2% at the surface 

layer and 9.1 % in the lower one, as indicated in table (4). 

- The salinity is very high and increased by depth. Table (5) 

- The soil pH was 7.5 which are due to the increase of salinity. 

- The soil has low percentage of CaCO3 content. 

- The color is varied from yellow (10yr 7/6 dry) to (very pale brown 7/4dry) and from 

yellowish brown (10yr 5/6 moist) to yellowish brown (10 yr 5/4 moist). Table (3) 

- According to the USDA soil taxonomy 1998 the soils Typic Salorthids. 

2. Alluvial plain 

The total area of this unit is 662.3 Km 2 (158952 fedden) and geographically could be divided 

into two parts from north to south as follows: 

a) From 22°30`N to Abu Ramad (22°20`N) 

b) From 22°20`N to Halaib (22°15`N) 

a) From 22°30`N to Abu Ramad (22°20`N) 

The total area of this unit is 245.7 Km2 (58968 fedden). It is represented by two profiles 

(profile 1 and profile 2) and characterized as following: 

- the surface is almost flat, covered by desert pavement in some places. 

214


- In the upper layer the soil texture is commonly fine sand, while in the subsurface it is 

commonly very gravelly coarse sand. 

- The soil surface is covered by some scattered young trees and some natural vegetation. 

- Generally the EC value of profile 1 is lower than 4 dS/m, while in profile 2 it is higher 

than 8 dS/m. 

- The mean CaCO3 content in profile 1 is lower than 2 %, and 4.5 %.in profile 2. 

- The soil taxonomy according to the USDA soil taxonomy 1998 is Typic Torrifluvents. 

215


Landscape 

Plain, P 

Mountain, 

M 

Relief 

Flat to gently 

undulating 

P1 

Almost flat 

to Hilly 

P2 

Almost flat 

to 

Hilly 

P2 

Undulating 

to hilly 

P3 

Hill or Mountain 

M1 

Lithology 

Alluvial 

Deposit 

P11 

Aeolian 

deposit 

P21 

Marine deposit 

P22 

Colluvial 

deposit 

P31 

Rock 

M11 

Landform 

Delta plain 

Alluvial plain 

Wadi 

Sand dunes 

Beach 

Sabkhas 

Costal plain 

Plain with Rock 

outcrop 

P311 

Denuded hill 

M111 

Mountain 

M112 

216 

Phase 

This soil covers most of the costal region and could be identified easily in the satellite image and 

classified as Typic Torrifluvents 

Flat, surface covered by desert pavement, varying texture from fine sand to gravelly coarse sand, common 

to many calcium carbonate and salt contents, classified as Typic Torrifluvents, Typic Haplosalids, and 

Typic Petrocalcids 

Alluvial, sandy texture, covered by silty crust (in some areas). This soil could be classified as Typic 

Torrifluvents 

Undeveloped soils consist of sand accumulation of different altitudes, barchanoid and longitudinal form 

the main dune types and could be classified as Typic Quartzpssaments 

Flat to undulating surface, some vegetation cover, loose, few to many calcium carbonate and salt 

contents. It could be classified as Typic Torripssaments 

Flat to undulating surface, sandy and strongly saline soils, shallow depth, highly saline gypsiferous origin, 

motels of iron and manganese oxide also exist. The soil could be classified as Typic salorthids 

Coarse sandy soils include gravels, less vegetation covers, medium calcium carbonate and salt content. 

Could be classified as Typic Torrifluvents 

The soil surface is covered by stones in different size mixed with sand and gravels, shallow depth, could 

be classified as Typic quartzpssament 

Area covered with big rocks and stones of different size 

rocks 

Table 2: The final legend of the classified image, zink, (1988) [9] 

Map. 

units 

P111 

P112 

P113 

P211 

P221 

P222 

P224 

P311 

M111 

M112 

Feddan 

(4200m 2 ) 

320 

158952 

5832 

400 

1360 

2064 

3120 

49248 

49248 

189660


Fig 2: Map of photomorphic units 

Fig 3: Location of the soil profile 

217


b) The alluvial plain from 22°20` N to 22°15`N 

This area is very narrow plain and has very small wadies namely; wadi Ashmahi, wadi Udar, 

wadi Ediab and wadi Cermatai. The total area is about 225 Km2 (54000 fedden) and is 

represented by profile 6, 9 and 10. 

The soil profiles are characterized as following: 

- The topography is almost flat; some small sandy hills could be noticed in some places due 

to the wind activity. 

- The texture is varied from fine to very gravely coarse sand. 

- Most of the soil profiles have a mean EC value over 8 dS/m, while in profile 6 it is very 

obvious in the sublayer. The variations of the EC values are in relation to the distance 

from the sea. 

- The CaCO3 content of most profiles is lower 4 %. It is over 8% in profile 10 and reaching 

45% in profile9. 

- Generally, the pH values are varied between 7 and 8.2. A reversible relationship between 

pH and EC values are obvious as indicated in profile 6 where the pH value is 8.1 and the 

EC value was 0.2 dS/m in the upper layer. While, in the lower layer the pH value was 7.4 

and the EC value was 11.2. This contradiction refers to the lowness of the buffering 

capacity of the sandy soils and the dominant of NaCl salt. 

- The soil taxonomy of this unit according to the USDA soil taxonomy 1998 is Typic 

Torrifluvents except for profile 9 is Typic Haplosalids and profile 10 is Typic 

Petrocalcides. 

3. Wadies 

This unit occupies a total area of about 24.3 Km (5832 feddens) could be divided into two 

sub unit namely; main wadi and tributaries. It is represented by profiles no. (Profile 3, 5, 7 

and profile 8) 

- The soil surface is flat to undulating covered by gravels varied in size from small to 

coarse gravel and few scattered natural vegetation. 

- Geomorphologicaly the wadi could be divided into three sub units namely; wadi bottom 

which is normally affected by water erosion, flood plain and wadi terraces. 

- The EC mean value is lower 2 dS/m in profile 3, and 8.6 dS/m in profile 5 (wadi Oshipa), 

while in profile 7 (wadi Udar) and profile 8 (wadi Ediab) it reaches 18.6. 

- 50% of the pH values of the studied soil profiles are varying between 7 and 7.5, the rest 

are 7.6 to 8.2. 

- Most of the CaCO3 values of the profile are very low except for profile 7 and profile 12, 

it reaches to more than 8% 

- The soil texture is varied from fine sand to very gravelly fine sand and from coarse sand 

to gravelly coarse sand. 

- The soil classification according to USDA soil taxonomy 1998 is Typic Torrifluvents. 

Table (3) 

4. Delta plain 

The total area of this unit is 320 fedden. This soils covers most of the costal region and can be 

identified in the satellite images. The soil can be classified as Typic Torrifluvents. 

218


Pro 

f. 

no. 

1 

2 

3 

4 

Locations 

Lg.: 22ُ 29` 

26.8" N 

Lt: 36ُ 5` 

12.6" E 

Lg. 22ُ 28` 

36.3" N 

Lt:36ُ 8` 00" 

E 

Lg. 22ُ 28` 

36.3"N 

Lt:36ُ 4` 

44.2" E 

Long. 22ُ 25` 

00' N 

Lat:36ُ 5` 

12.6" E 

Map. 

units 

vegetat 

ion 

draina 

ge 

P112 few well 

P112 common well 

P113 few well 

P216 few well 

Parent 

material 

Alluvial 

deposit 

Alluvial 

deposit 

Alluvial 

deposit 

Marine 

deposits 

classification 

Typic 

Torrifluvents 

Typic 

Haplosalids 

Typic 

Torrifluvents 

Typic 

Aquisalids 

219 

Depth 

Cm. 

0-15 

15-50 

50-100 

0-15 

15-35 

35-70 

0-25 

25-40 

40-60 

60-100 

0-15 

15-45 

45-100 

color 

dry moist 

10 YR 

7/3 

10 YR 

6/6 

10 YR 

7/3 

10YR 7/4 

10 YR 

7/8 

10 YR 

7/8 

10 YR 

7/2 

10 YR 

7/4 

10 YR 

7/6 

10 YR 

7/6 

10 YR 

7/6 

10 YR 

7/4 

10 YR 

7/4 

5/4 

5/6 

5/4 

6/3 

5/4 

6/4 

5/3 

5/3 

6/6 

6/8 

5/6 

5/6 

5/4 

text 

ure 

FS 

FS 

GCS 

GFS 

VGCS 

GCS 

GFS 

GFS 

CS 

GCS 

FS 

FS 

FS 

Struct 

ure 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

consis 

tence 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

effe 

rves 

cenc 

e 

s 

s 

st 

s 

v 

s 

vs 

st 

s 

s 

vs 

st 

st 

bounda 

ry 

d 

d 

- 

c 

cw 

cw 

d 

d 

d 

- 

cs 

cs 

-


5 

6 

7 

8 

9 

Lg. 22ُ 23` 

36.32" N 

Lt:36ُ 19` 

31.6" E 

Lg. 22ُ22`00' N 

Lt:36ُ 25`00"E 

Long. 22ُ 20` 

00" N 

Lat:36ُ 25` 

42.6" E 

Long. 22ُ 

18`31.6" N 

Lat: 36ُ 25` 

25.3" E 

Lg. 22ُ 18` 00" 

N 

Lt:36ُ 26` 

23.7" E 

P112 few well 

P112 few well 

P113 few well 

P113 few well 

P311 common well 

10 Lg. 22ُ 18` 00" P112 Few well 

Alluvial 

deposits 

Alluvial 

deposits 

Alluvial 

deposits 

Alluvial 

deposits 

Colluvial 

deposits 

Typic 

Torrifluvents 

Typic 

Torrifluvents 

Typic 

Torrifluvents 

Typic 

Torrifluvents 

Typic 

Haplocalcids 

Alluvial Typic 

220 

0-15 

15-30 

30-100 

0-30 

30-60 

60-150 

0-25 

25-55 

55-100 

0-25 

25-80 

80-100 

0-25 

25-70 

0-15 

10 YR 

7/8 

10 YR 

7/4 

10 YR 

7/6 

10 YR 

7/3 

10 YR 

7/4 

10 YR 

7/4 

7.5 R 

6/6 

7.5 YR 

6/6 

7.5 YR 

7/6 

10 YR 

6/4 

10 YR 

6/6 

10 YR 

6/4 

10 YR 

7/6 

10 YR 

7/4 

10 YR 

6/6 

6/4 

5/6 

5/4 

5/6 

5/4 

5 YR 4/6 

7.5 YR 

4/4 

7.5 YR 

5/8 

5/4 

6/8 

5/4 

5/4 

6/3 

GFS 

GFS 

GCS 

GFS 

GCS 

GCS 

VGFS 

GCS 

VGCS 

FS 

GFS 

FS 

FS 

GFS 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

Sg 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

dL 

st 

s 

s 

s 

vs 

st 

st 

s 

vs 

st 

st 

st 

v 

v 

cs 

cs 

- 

d 

cs 

- 

d 

cs 

- 

d 

cs 

- 

d 

cs 

5/6 GFS Sg dL v c


N 

Lt:36ُ 24` 

39.5" E 

deposits petrocalcids 15-30 

Where: -Texture: FS= fine sand, GFS= gravelly fine sand, VGFS= very gravelly fine Sand, GCS= gravelly coarse sand, VGCS= very gravelly 

coarse sand 

-Structure: Sg= single grain -Consistence: d=dry, L=loose - Boundary: c=clear, d= diffuse, s=smooth 

- effervescence with HCl: vs= very slight, s= slight, st= strong, v= violent 

221 

30-100 

7/4 

10 YR 

5/3 

10 YR 

7/2 

4/4 

7.5 YR 

4/4 

Table 3: Morphological description and classification of the studied soil profiles 

GFS 

VGFS 

Sg 

Sg 

dL 

dL 

v 

v 

d 

-


5. Beach 

The area of this unit is 1360 fedden. Almost flat to undulating, some vegetation cover, loose, 

few to many calcium carbonate and salt content could be classified as Typic Torripssament 

6. Sand dunes 

The total area of this unit is 400 fedden. Undeveloped soils consist of sand accumulation of 

different altitudes, barchanoid and longitudinal forms area the main dune type. Could be 

classified as Typic Quartzpssaments. 

7. Coastal plain 

The total area of this unit is 3120 fedden. the soil surface is sloping towards the sea and the 

soil originated from alluvial deposit mixed with marine deposit. Coarse sandy soils, include 

gravels, less vegetation covers, medium calcium carbonate and salt content, the surface 

covered with shells. It could be classified as Typic Torrifluvents. 

Profile 

nr. 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

Soil depth 

(cm) 

0-15 

15-50 

50-100 

0-15 

15-35 

35-70 

0-25 

25-40 

40-60 

60-100 

0-10 

10-45 

45-100 

0-15 

15-30 

30-100 

0-30 

30-60 

60-150 

0-25 

25-55 

55-100 

0-25 

25-80 

80-100 

0-20 

20-70 

0-15 

15-30 

Gravel 

>2mm 

% 

2.5 

3.4 

23.7 

35.7 

54.0 

47.1 

38.5 

40.4 

17.4 

50.0 

17.2 

3.1 

9.1 

38.8 

46.5 

42.9 

37.4 

31.4 

68.2 

54.9 

27.9 

34.1 

17.7 

42.3 

-- 

14.7 

12.9 

42.4 

36.0 

2-1 

VCS 

9.5 

9.1 

29.8 

5.0 

29.0 

32.0 

9.1 

8.8 

30.1 

31.2 

7.9 

10.6 

10.1 

10.0 

8.1 

22.3 

6.4 

31.1 

20.1 

6.6 

27.0 

28.1 

7.9 

7.7 

8.6 

10.4 

12.9 

10.9 

10.7 

Percentage of separate particles (mm) 

1-0.5 

CS 

10.5 

10.1 

10.9 

12.0 

18.8 

17.3 

12.5 

12.3 

17.9 

16.3 

10.4 

9.8 

9.1 

7.7 

9.8 

20.9 

11.3 

18.7 

21.2 

8.1 

13.3 

12.1 

11.5 

13.4 

12.5 

10.4 

9.7 

11.9 

9.3 

0.5- 

0.25 

MS 

17.3 

19.2 

29.7 

18.1 

31.9 

27.4 

18.1 

17.7 

32.7 

28.5 

19.4 

12.2 

20.1 

21.7 

22.8 

30.0 

20.3 

23.8 

23.0 

19.6 

30.1 

30.2 

16.9 

16.3 

17.4 

16.0 

17.9 

16.5 

17.6 

222 

0.25-0.1 

FS 

43.8 

50.2 

18.5 

46.0 

14.4 

16.2 

44.4 

46.0 

12.4 

11.4 

50.0 

52.2 

46.5 

49.0 

44.5 

20.3 

43.3 

17.9 

27.9 

56.9 

23.8 

23.3 

41.5 

44.7 

43.6 

41.6 

41.4 

40.9 

40.3 

0.1-0.05 

VFS 

12.5 

8.4 

7.0 

10.9 

2.8 

5.4 

9.9 

9.0 

2.9 

4.0 

9.9 

11.1 

10.1 

8.8 

11.9 

5.0 

13.4 

4.8 

4.9 

4.9 

2.8 

3.2 

16.2 

13.3 

13.4 

13.2 

13.6 

13.7 

14.4 

Table 4: Grain size distribution 


223 

Soluble cations me/L Soluble anion me/L 

Profil 

e nr. 

Depth in, 

Cm 

S.P. 

EC 

ds/m 

pH CaCO3 % 

OM 

% Na + K + Ca ++ Mg ++ 

HCO3 

- 

Cl - CO3 -- SO4 ++ 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

0-15 

15-50 

50-100 

0-15 

15-35 

35-70 

0-25 

25-40 

40-60 

60-100 

0-10 

10-45 

45-100 

0-15 

15-30 

30-100 

0-30 

30-60 

60-150 

0-25 

25-55 

55-100 

0-25 

25-80 

80-100 

0-20 

20-70 

0-15 

15-30 

30-70 

21.8 

19.1 

20 

23.1 

22 

19 

18 

18 

20 

20 

21 

22 

21 

21 

22 

22 

21 

18 

21 

19 

21 

22 

19 

22 

21 

22 

20 

20 

21 

22 

0.8 

0.36 

0.41 

11.45 

25.4 

16.4 

1.43 

0.5 

0.69 

3.58 

20.6 

26.9 

23.6 

1.92 

1 

5.4 

0.92 

2.9 

11.2 

14.53 

11.6 

4.99 

5.4 

8.9 

14.9 

23.9 

6.8 

12.1 

2.9 

5.9 

7.8 

7.9 

7.9 

8.2 

7.2 

7.2 

7.9 

8.2 

8 

7.9 

7.5 

7.6 

7.9 

8 

7.9 

8.2 

8.1 

8 

7.4 

7.6 

7.8 

7.8 

7.9 

8 

7.8 

8 

8 

8 

7.7 

8.2 

0.1 

1.3 

2 

1.6 

1.3 

3.6 

0.76 

4.9 

2.09 

0.83 

6.4 

5.4 

14.2 

8.1 

4.5 

9.8 

2.1 

1.8 

7.1 

1.05 

0.09 

1.6 

9 

10.1 

3.93 

45 

12.8 

40.9 

28.5 

19.8 

0.36 

0.23 

0.29 

0.5 

0.23 

0.21 

0.01 

0.07 

0.07 

0.06 

0.04 

0.02 

0.01 

0.5 

0.02 

0.02 

0.2 

0.02 

0.01 

0.53 

0.02 

0.02 

0.2 

0.28 

0.14 

0.04 

0.01 

0.06 

0.01 

0.01 

0.8 

0.78 

0.7 

69.8 

163.9 

15.6 

0.14 

2.7 

0.19 

0.47 

34.4 

5.56 

15.5 

3.56 

6 

42.9 

0.12 

0.27 

.96 

54.35 

54.4 

0.53 

43 

60 

18.9 

210 

46 

0.24 

18 

46 

0.12 

0.1 

0.05 

3 

0.55 

0.4 

0.01 

0.4 

0.01 

0.02 

0.09 

0.17 

0.09 

0.06 

0.4 

0.4 

0.01 

0.02 

0.05 

0.82 

1.7 

0.05 

1 

0.6 

0.16 

0.5 

2.2 

0.01 

0.6 

0.3 

1.05 

0.65 

0.54 

29.9 

41.51 

19.71 

0.14 

1 

0.08 

0.23 

6.93 

7.53 

9.61 

0.74 

2.7 

12.6 

0.02 

0.03 

0.2 

50.52 

46 

0.27 

11.4 

21.8 

4.29 

52.1 

24.2 

0.03 

7.4 

12.5 

0.22 

0.21 

0.1 

15.6 

36.9 

11.3 

0.05 

0.6 

0.12 

0.14 

6.38 

2.97 

5.8 

0.46 

1.1 

6.1 

0.0`4 

0.1 

0.78 

21.5 

5.6 

0.69 

7.8 

12.8 

3.57 

23.9 

7.6 

0.05 

5.4 

7.5 

0.52 

0.6 

0.61 

5.4 

4.1 

3.6 

0.17 

0.9 

0.15 

0.15 

0.72 

0.76 

0.45 

0.08 

0.9 

4.6 

0.04 

0.03 

0.42 

4.08 

4.29 

0.17 

5.3 

11.6 

0.39 

17.6 

9.3 

0.12 

3.8 

6.3 

1.01 

0.5 

0.5 

81.3 

200.1 

29.9 

0.12 

2.6 

0.16 

0.24 

10.2 

2.22 

2.05 

2.29 

5.3 

41.3 

0.14 

0.37 

0.96 

82.93 

72 

0.72 

47.5 

67.5 

15.03 

245 

50 

0.16 

23.5 

45.7 

- 

- 

- 

- 

- 

- 

- 

0.5 

- 

- 

- 

- 

- 

- 

0.4 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

- 

0.064 

0.62 

0.31 

31.4 

40.3 

13.5 

0.05 

0.7 

0.1 

0.77 

36.92 

13.25 

9.86 

2.25 

3.5 

16.1 

0.01 

0.02 

0.6 

40.19 

41.41 

0.65 

10.4 

15.7 

11.5 

23.9 

20.7 

0.05 

4.1 

14.3 

Table 5: Analysis of soil paste extract


8. Plain with rock outcrop 

The soil surface is covered by stones in different size mixed with sand and gravels, shallow 

depth and it could be classified as Typic quartzpssament 

9. Denuded hills 

The total area of this unit is 49248 fedden. Area covered with big rocks and stones of 

different size 

10. Mountain 

The total area of this unit is 189660 fedden. Rocks. 

REFERENCES 

[1] A.P.A., Vink "Aerial photographs and soil sciences". UNESCO report, Paris, (1963). 

[2] C. A., Black; D.D., Evans; L.E., Ensminger; J.L, White and F.E., Clark."Methods of soil analysis". Medison: 

American Society of Agronomy. IAC., Medison, Wisconsin, USA., (1985) 

[3] C. S., Piper "soil and plant analysis". Inter science Publishers, Inc., New York, PP.59-75, (1950). 

[4] Desert Research Center (1994). Reconnaissance studies for natural and human resources in El-Shalatein- 

Halaib. Supervising committee on Technical studies and natural resources of El-Shalatein-Halaib region, D.R.C. 

Mataria, Cairo, Egypt (in Arabic). 

[5] Egyptian General Petroleum Cooperation Staff "Geological map of Egypt scale 1:500000". The Egyptian 

General Petroleum Cooperation, Cairo, Egypt, (1987). 

[6] Egyptian Geological Survey and Mining Authority Staff "Geological map of Egypt, Scale 1:2000000". 

Ministry of industry and mineral resources, Cairo, Egypt, (1981). 

[7] F. A., Hammad "Water situation in El-Shalatien- Halaib region sustainable agriculture potentiality". 

International Egyptian center of Agriculture, Cairo, Egypt. Report (in Arabic). (1994). 

[8] F.A.O. staff "Guidelines for soil profile description". F.A.O. soil Bulletin 6, F.A.O, (1966). 

[9] J. A., Zink "Geomorphology and soils", internal publ., I.T.C. Enschede, (1988). 

[10] J., Bennema and M. F., Gelons "Aerial photo interpretation for soil survey". Lecture note, I.T.C. courses 

photo-interpretation in soil survey I.T.C., Enschede, The Netherlands, (1969). 

[11] L. A., Richards "Diagnosis and improvement of saline and alkali soils". U. S. Dep. Of Agric. Hand Book, 

No. 60, pp. 102, (1954). 

[12] M. L., Jackson (1973). Soil chemical Analysis. Inter. Sci. pub. Inc., N.Y. 

[13] M. S., Abu Al-Ezz "Land form of Egypt'. Jojn Wiley and sons., Inc., New York. (1987). 

[14] M., El-Rakaiby; T., Ramadan; A., Morsy and M., Ashmawe "Geological and geomorphological studies of 

Halaib and Shalatien region and its relation to surface and subsurface water". NARSS, Cairo, Egypt, (1996). 

[15] R., Said (1990). "The geology of Egypt". A. A. Balkema, Rotterdam, Brookfield (1990). 

[16] USDA (1998) "key to soil taxonomy". SCC, SMSS Technical Monograph 19, USDA, USA., (1987). 

224


HIGH RESOLUTION TERRAIN MAPPING AND 

VISUALIZATION OF CHANNEL MORPHOLOGY USING LIDAR 

AND IFSAR DATA 

Sudhir Raj Shrestha 1* , Dr. Scott N. Miller 2 

1 Graduate Research Assistant, University of Wyoming, Department of Renewable Resources, Laramie, WY 

82071, USA, Email: sudhir@uwyo.edu, Phone: 1-307-766-5305, Fax: 1-307-766-6403, 2 Professor 


Channel morphology characteristics play crucial roles in the understanding and interpretation 

of the geomorphic and hydrologic characteristics of an area. Conventional techniques for 

determining channel width, depth and cross-section area is time consuming and most of the 

time may not represent the spatial variability within the watershed. This poster presents an 

overview of the methods for extracting average channel morphology characteristics on a 

channel reach basis from a high resolution Digital Elevation Model (DEM) of 1m and 2.5m 

respectively build from Light Detection and Ranging (LiDAR) and Interferometric Aperture 

Radar (IFSAR) for 150 km 2 USDA-ARS Walnut Gulch Experimental Watershed in Arizona. 

LiDAR is an active remote sensing technology used on a satellite or airborne platform. 

By the use of laser light for reflection, high precision kinematic DGPS (differential global 

positioning systems) for position information, and an IMU (intertial measuring unit, also 

know as inertial navigation system, INS) for altitude calculations, this system can collect high 

density, highly accurate topographic and bathymetric data. Digital products delivered to the 

end user include a grid or irregular network of XYZ data points with maximum vertical 

accuracy on the order of 15 cm and horizontal spacing on the order of 1m, but under some 

circumstances as fine as 30-60 cm. This technology holds the promise of producing fine 

resolution digital elevation model (DEM) for use in soil survey, subaqueous soil survey, and 

other related pedologic and geomorphological work. 

IFSAR is an active remote sensing technology used on satellite or aircrafts. It 

combines complex images recorded by antennas at different locations or at different times. It 

is an alternative to conventional stereo photographic techniques for generating high 

resolution topographic maps. 

The primary objective of this project was to evaluate the accuracy of the LiDAR and 

IFSAR data in estimating channel morphology and build an input for Predictive Soil 

Mapping (PSM) project. An approach was developed in a geographic information system 

(GIS) to extract cross-section profiles on a stream system derived from the topographic 

models. Simultaneous to the acquisition of LIDAR data a field campaign was undertaken by 

to evaluate the accuracy of the LiDAR DEM; a total station was used to evaluate cross 

sections at 22 sites within the study area. Manual interpretation was required to identify the 

bank location from the profiles extracted from the GIS, after which average channel 

morphologic properties of width, depth and cross-section area were determined. 

Results from both the LiDAR and IFSAR data were highly correlated with field 

observations, although the LiDAR data performed significantly better in terms of the ability 

to determine channel depth. These results illustrate the benefits of using high resolution data 

in hydrologic and geomorphic study, and show promise towards the development of a fully 

automated system for extracting channel morphology from surface terrain models which can 

be used as one of the proxies of soil forming factors in PSM. 

225


Sub-theme : DEVELOPMENTS IN SOIL SAMPLING AND 

PROXIMAL SENSING WITH APPLICATIONS IN PRECISION 

AGRICULTURE 

M. van Meirvenne, U.W.A. Vitharana L. Cockx 

2 Research unit Soil Spatial Inventory Techniques, Dept. of Soil Management & Soil Care, Coupure 653, Ghent 

University, Gent, Belgium 

Detailed soil spatial information has become indispensable for a variety of agronomic and 

environmental applications. Precision agriculture is one of the applications which refers to a 

crop management concept that allows for variable management practices within a field 

according to soil or site conditions. The economic and environmental benefits of precision 

agriculture have stimulated the research interest and farmer adoption level in developed 

countries. Moreover, there are evidences for the potential applications of precision agriculture 

technology in developing countries with proper adjustments. Intensive soil sampling and 

analysis is not a realistic alternative to explore the detailed soil spatial variation due to cost 

constraints. The advances in soil sensing technology, global positioning systems (GPS) and 

spatial prediction techniques make it possible to acquire accurate high resolution soil 

information in a cost effective manner. The user friendly geographical information systems 

have provided tremendous opportunities to analyze, display and inventory soil information. 

Consequently, new digital soil mapping techniques are aimed to produce soil inventories with 

5 m resolution [6]. 

Proximal soil sensing is widely accepted as a suitable ancillary information source for 

detailed soil mapping. Currently, different types of proximal soil sensor techniques are 

available. These include electromagnetic induction (EMI), magnetics, soil resistivity, 

spectrometry, ion selective field effect transistors, aerial digital photography and ground 

penetrating radar. In addition, combines mounted with crop yield sensors became 

commercially available in the last decade. These sensors are capable to reflect the spatial 

variability of different crop and soil properties, e.g. the EMI based EM38 sensor 

measurements reflect soil textural variation. Proximal sensors are coupled to a GPS receiver 

and a data logger to obtain large numbers of on-the-go georeferenced measurements. The 

spatial variation observed with sensor information can be used to design a targeted field soil 

sampling scheme consisting of a limited number of samples [2]. The relationships identified 

between the proximal sensor information and soil properties are used to predict soil variation 

using appropriate prediction technique. The prediction approaches include techniques such as 

geostatistical methods, different forms of regression, neural networks and Bayesian 

maximum entropy. The clustering procedures like fuzzy k-means algorithm facilitate to 

identify within-field zones characterized with a unique combination of soil properties to 

manage crops at a within-field scale. 

REFERENCES 








226









Space (2003). 




428, (2005). 













52, (2003). 



[101] K. Taillieu, R. Goossens, D. Devriendt, A. Dewulf, S. Van Coillie, T. Willems. "Generation of DEMs 

and orthoimages based on non-stereoscopical IKONOS images", New Strategies for European Remote Sensing, 





[103] G. Zhou, R. Li. "Accuracy evaluation of ground points from IKONOS high-resolution satellite 

imagery", Photogrammetric Engineering and Remote Sensing, 66 (9), 1103-1112, (2000). 

227


ESTIMATING SPATIAL VARIABILITY OF SOIL SALINITY 

USING COKRIGING IN BAHARIYA OASIS, EGYPT 

Abstract 

Kh. M. Darwish*, M.M. Kotb and R. Ali 

Soils & Water Use Dept., National Research Centre (NRC), Cairo, Egypt. 

* kdarwish@hotmail.com 

The mapping of saline soils is the first task before any reclamation effort can be conducted. 

Soil salinity is determined, traditionally, by soil sampling and laboratory analysis. Recently, it 

became possible to complement these hard data with soft secondary data made available 

using field sensors like electrode probes or satellite images. Estimating spatial variability of 

soil salinity is an important issue in precision agriculture. 

In this study, geostatistical method of cokriging, were applied to estimate and identify the 

spatial variability of soil salinity with ECe measurements in 200 km 2 agricultural fields in the 

north and south Bahariya oasis. In cokriging, more densely sampled secondary data from the 

ETM satellite image source were incorporated to improve the estimation of the electrical 

conductivity (ECe). The estimated spatial distributions of ECe using the geostatistical 

methods with various reduced data sets were compared with the extensive salinity 

measurements in the large field. The results suggest that sampling cost can be dramatically 

reduced and estimation can be significantly improved using cokriging. Compared with the 

kriging results using only primary data set of ECe, cokriging with reduced data sets of ECe 

improves the estimations greatly by reducing mean squared error and kriging variance up to 

70% and increasing correlation of estimates and measurements about 25%. Relative 

improvements in map accuracy were highest (25% to 38%) in regression colocated cokriging 

approach, which also performed better than ordinary kriging method that utilized only one 

ancillary variable. The relative gain from incorporating remote sensing secondary 

information increased with decreasing sampling density. The results of these models allow to 

interpolate and classify salinity on a more realistic and continuous scale. 

Keywords: soil salinity - spatial variability - cokriging algorithm – colocated cokriging. 

Introduction 

Soil salinity limits food production in many countries of the world. There are mainly two 

kinds of soil salinity: naturally occurring dryland salinity and human-induced salinity caused 

by the low quality of water. In both cases the development of plants and soil organisms are 

limited leading to low yields. In Bahariya oasis, where more than 10% of the land is affected 

by salt, groundwater and inadequate drainage conditions are the major causes of salinization. 

Generally, the classical soil survey methods of field sampling, laboratory analysis and 

interpolation of these field data for mapping, especially in large areas is relatively expensive 

and time consuming. Remote sensed data might be a useful tool to overcome these 

problems. Dwivedi (1992) used Landsat MSS and TM data for more detailed mapping and 

monitoring of the salt affected soils in the frame of the reconnaissance soil map of India. 

Also, De Dapper and Goossens (1996) indicated the development of GIS and remote sensing 

for monitoring and predication of soil salinity in the Desert-Delta fringes of Egypt. 

Conventionally (Soil and Plant Analysis Council, 1992) soil salinity is determined by 

laboratory analysis (electrical conductivity of the saturated soil paste extract ECe). This 

228


procedure is expensive and time-consuming, and provides an incomplete view of the extent 

of soil salinity. An alternative to laboratory analysis is to assess soil salinity in the field by 

determining the apparent electrical conductivity (ECa). This can be done using sensors such 

as the four-electrode probes (Rhoades and van Schilfgaarde, 1976) or by electromagnetic 

induction instruments (McNeil, 1980). This procedure is cheaper and less time-consuming 

and enabling a more intensive survey of the study area. Creating maps typically involves 

sampling, measuring the variable of interest, and estimating values at unsampled locations 

through some form of interpolation, plain regression, data aggregation, or other prediction 

techniques (McBratney et al., 2003). 

Geostatistics offers a collection of deterministic and statistical tools aimed at 

understanding and modeling spatial variability. Hybrid geostatistical procedures that account 

for environmental correlation have become increasingly popular in recent years because they 

allow utilizing secondary information that is often available at finer spatial resolution than the 

sampled values of a primary target variable. If the correlation between primary and secondary 

variables is significant, hybrid techniques generally result in more accurate local predictions 

than ordinary kriging or other univariate predictors (Goovaerts, 1999; McBratney et al., 2000; 

Odeh et al., 1994; Triantafilis et al., 2001). 

Cokriging is the extension of kriging to more than one variable. It is most likely to be 

beneficial where the primary variable (the one be estimated) is under sampled with respect to 

the secondary variable(s) that are assumed to be correlated with the primary variable. In some 

applications there are only a few measurements of the attribute of interest; the resultant 

predicated maps have poor resolution and the corresponding uncertainty may be very large. 

In such situation it is critical to account for secondary, indirect information that may be more 

densely sampled (Goovaerts, 1997). 

In this way, colocated cokriging is as reduced form of full cokriging. It requires only 

knowledge of the semivariogram of the primary variable and the cross-variogram between the 

primary and secondary variable (Curran & Atkinson, 1997). Furthermore, the combination of 

geostatistics and remote sensing techniques has been used before to study and assess the 

magnitude and extent of spatial variability in soil salinity (Lesch et al., 1995; Christakos & 

Li, 1998.; Darwish, 1998). 

This study aims to map soil salinity in the northern and southern part of Bahariya oasis 

using geostatistical techniques, integrating a limited data set of soil salinity measurements 

(ECe) as a primary variable with ETM satellite image as a secondary data source. The result 

of this methodology will be qualified using the cross validation method. 

Material and methods 

Study site description 

Bahariya depression is located nearly in the middle of the Western desert of Egypt and 

comprising a total area of approximately 2250 km 2 (Fig.1). The area falls under the arid 

condition as the total rainfall is (3-6) mm/year. Springs and wells are the main two 

groundwater resources for irrigation and civic purposes (Salem, 1987). In Bahariya, it is 

found that the main unsuitability criteria eliminating more extend of cultivation areas is the 

excess of salts. In this research, two study areas were selected. One is in the north of Bahariya 

covering an area of about 118.3km 2 and the second is covering partly the southern part of it 

with an area of 77.5km 2 (Fig.2). 

229


Data description 

Based on the pre-field and information obtained, 45 soil profiles and 71 soil augers were 

examined in different locations. Fig. 3a and 3b show the location of the observation sites 

where soil samples were taken. Four transects in area1 and two in the southern one. Electrical 

conductivity soil salinity measurements (ECe) dS/cm were determined in the soil water 

extract out of the saturated soil paste. Total of six sample areas were selected and distributed 

over the study areas with a fixed wide of 1km for each. The exact locations of the soil 

profiles and auger points were precisely defined in the field by using the DGPS, and plotted 

on the maps. 

Figure 1 & 2. Location and the study areas in N and S Baharyia. 

Figure 3a. Location of sample points in study area-1 (North). 

230


Figure 3b. Location of sample points in study area-2 (South).Fig. 4a and 4b show the frequency 

distribution of ECe (dS/cm) values in study areas-1 and 2 respectively. The first one exhibit abnormal 

distribution, while the second is normally distributed, which does not deemed Ln transformation. 

Although the Ln transformation ECe semivariogram can give a better fitting, but the problem of back 

transformation through the estimation procedure is limiting its usability. 

Frequency 

9,0 

6,8 

4,5 

2,3 

0,0 

0,96 59,97 118,99 178,00 

231 

"ECe" 

Figure 4a. Frequent distribution of ECe values in study area-1. 

Frequency 

Method of geostatistical analysis 

3 

2 

2 

1 

0 

0,86 44,57 88,29 132,00 

"ECe" 

Figure 4b. Frequent distribution of ECe values in study area-2 

The variability of soil salinity representing horizontal distribution of salts in continuous 

model was mapped. The study shows that it is possible to map soil salinity variability using


an appropriate interpolation technique. The part of the study, as reported here, includes 

reconstructing the spatial variability of salinity; and evaluating the accuracy to predict 

electrical conductivity measurements. 

Geostatistical methods can be used to measure and model the spatial correlation of soil 

salinity measurements as a primary variable and the satellite image as a secondary data 

variable. The models of spatial correlation are then used along with Kriging and the new 

geostatistical technique of Collocated Cokriging to develop large scale maps showing the 

spatial pattern of soil salinity status in the selected study area. 

Colocated Cokriging 

As mentioned before, Cokriging is the extension of Kriging to more than one variable. 

Colocated cokriging is as reduced form of full cokriging. 

Considering Z (the primary variable) = 1 and Y (The secondary variable) = 2 

Then, colocated cokriging with Markov-type approximation of attribute Z at location X 

is given by: 

Z*cok (u) = n i=1∑ λ1i (u) Z (ui) + λ2 (u) [Y (u) + mz - my] (1) 

Where: 

Z*cok (u): cokriging estimator of Z(u) 

λ1i (u): cokriging weight associated to neighboring datum Z(u) for estimation at location u. 

λ2 (u): cokriging weight associated to collocated secondary datum Y(u). 

mz: mean of the primary variable (ECe measurements). 

my: Mean of the secondary variable (Satellite data). 

In this study, colocated cokriging was applied to map soil ECe values, from available 

ECe data as primary data and ETM Satellite image as densely sampled secondary data 

source. When the collocated secondary variable Y (u) is known everywhere and varies 

smoothly across the study area (e.g., satellite data & surface reflectance) there is little loss in 

retaining in the cokriging system, provided that it is available at each location u being 

estimated (Xu et al., 1992; Goovaerts, 1998b). This is clear the case in remote sensing where 

the secondary variable is provided by remotely sensed imagery data, which often completely 

covers the area of interest. 

Selection of the imagery 

Two smaller windows of a complete Landsat 7 Enhanced Thematic Mapper (ETM) satellite 

image of Bahariya Oasis dated in 21-04-2002 were chosen to be used in this study (Fig.2). 

The False Color Composite (FCC) of these image windows is covering area-1 as shown in 

Fig. 3a and area-2 in Fig. 3b. The first image window is within the Northern part of Bahariya 

depression, which is covering most of the villages located there. The second one is covering 

partly the southern part of Bahariya. 

The following geo-morphological features are covered by image one from north to 

south: 

1- Maysera Plateau, escarpment and plateau footslope. 

2- Mandisha Hill, hilland and footslope. 

3- Peneplain sand sheet and rock out crop. 

4- Plain sand sheet, sand flat and playa. 

On the other hand, the following geo-morphological features can be recognized in image two: 

1 Plain sand sheet, sand flat, playa and isolated conical hills. 

232


2 Plateau footslope and escarpment. 

Exploratory data analysis 


Some statistics about the hard data (ECe) for areas-1 &-2 are reported in Table 1. It was 

noted the presence of a strong spatial variability. For example in areas 1 & 2, there is a big 

difference between the extreme values (minimum and maximum). In addition, to improve 

estimation accuracy, the correlation between the primary and secondary variables should be 

as high as possible. Therefore, the Pearson correlation coefficient was applied on the ECe 

values that were available and the colocated reflectance measurements provided by the eight 

spectral bands of the ETM image. It is found, that the highest correlation (r≅0.3) of the ETM 

bands with the EC observations is signed for the ETM low gain band 6 (Fig. 5). At study 

areas 1 and 2, the relationship between EC and surface reflectance REF was probably masked 

by the sand sheet and flat layer on the soil surface, which had accumulated as a result of 

geological history and greatly affected surface reflectance shown in the satellite image, but 

not mainly EC. The oldest rocks exposed within Bahariya depression are sandstone, siltstone 

and clay of Cenomanian age that cover the floor of the depression and crop out along the base 

of the escarpment (Parsons, 1962). 

In this way, the secondary variable could be determined for every pixel covered by the image. 

Items Mean Standard Deviation Sample variance Min. Max. 

Area 1 (N) 37.27 46.51 2163.06 0.96 178.0 

Area 2 (S) 51.26 39.41 1552.79 0.86 132.0 

Correlation Coefficient 

Table 1. Statistical summary of ECe (dS/cm) data. 

0.3 

0.25 

0.2 

0.15 

0.1 

0.05 

0 

-0.05 

1 2 3 4 5 6 7 8 

ETM spectral bands 

Figure 5. The Correlation Coefficient statistical analysis among primary and secondary variables. 

(All correlations were significant at P < 0.001 level). 

On the other hand, the frequent distribution of the colocated reflectance measurements 

of ETM low gain band 6 for area 1 and 2 is illustrated in Fig. 6a & 6b. 

233


Frequency 

8 

6 

4 

2 

NonTransformed 

0 

148.0 169.0 190.0 211.0 

ETM LG band 6 

Figure 6a. Frequent distribution of ETM low 

gain band 6 for area-1. 

234 

Frequency 

2 

2 

1 

1 

NonTransformed 

0 

161.0 177.0 193.0 209.0 

ETM LG band 6 

Figure 6b. Frequent distribution of ETM low 

gain band 6 for area-2. 

The reflectance values of ETM LG band 6 were standardized to zero mean and unit variance 

for each study area and re-combined into one dataset of standardized the field surface 

reflectance (REF) for whole study area. The confirmed Regression Coefficient of (ETM LG 

band 6) with the EC observations for study areas 1 and 2 is indicating relatively higher 

correlation for area-1 than area-2 (Fig. 7a & 7b). 

Primary ("EC") 

178.00 

133.74 

89.48 

45.22 

0.96 

148.00 169.00 190.00 211.00 

Covariate ("ETM LG 6") 

Regression coefficient = 0.9 (SE = 0.6, r2 =0.065, y intercept = -126.705, n = 31) 

Figure 7a. The Regression Coefficient among 

variables (Z & Y) in area-1 

Structure analysis 

Primary (EC) 

132.00 

99.22 

66.43 

33.65 

0.86 

161.0 177.0 193.0 209.0 

Covariate (ETM LG band 6) 

Regression coefficient = 0,6 (SE = 0,8, r2 =0,047, y intercept = -72,154, n = 14 

Figure 7b. The Regression Coefficient among 

variables (Z & Y) in area-2. 

It is necessary to analyze the spatial variability of the data above by semivariance function. 

Fig. 8a and 8b illustrate the semivariance value of primary variable (ECe) of study areas 1 & 

2. The sill of EC in areas 1 & 2 are 2620.0m and 1845.0m and their correlation lag range 

3710.0m and 1120.0m respectively


Semivariance 

5805 

4353 

2902 

1451 

0 

0.0 2596.0 5192.0 7788.0 

Separation Distance (h) m 

Figure 8a. Isotropic variogram (spherical model) 

of ECe (dS/cm) in area-1. 

235 

Semivariance 

3482 

2611 

1741 

870 

0 

0.0 2257.7 4515.3 6773.0 


Figure 8b. Isotropic variogram (spherical model) 

of ECe (dS/cm) in area-2. 

The variogram shows a relative nugget effect of 11.7% for study area-1 and 10.0% for area-2, 

which cloud be calculated through this ratio [(C /(C + C)) x 100] between nugget variance 

0 0 

and sill. The nugget effect looks more significant in study area-2 than area-1, which causes 

by random factors. 

On the other hand, as Cokriging is a multivariate extension of kriging, when the 

secondary variable is known everywhere and varies smoothly across the study area (e.g., 

colocated reflectance measurements provided by ETM low gain band 6) there is little loss in 

retaining in the cokriging system. The secondary variable provides information only about 

the primary trend at location u. 

In order to apply a colocated cokriging method a cross-semivariance analysis must be 

performed prior to cokriging, where CZY(ui - u) is the cross covariance between primary and 

secondary variables at locations ui and u, respectively. Again, the common practice consists 

of estimating and modeling the (cross) semivariogram, then retrieving the (cross) covariance. 

Fig. 9a and 9b show the experimental semivariogram of the secondary variable ETM LG 

band6 and cross semivariogram with the primary one (ECe point observations) for study 

area-1, computed as: 

(2)


Semivariance 

394.7 

263.1 

131.6 

"ETM LG 6": Isotropic Variogram 

0.0 

0.0 2596.0 5192.0 7788.0 


Figure 9a. The semivariogram of secondary 

variable for study area-1 

236 

Semivariance 

"EC" x "ETM LG 6": Isotropic Cross Variogram 

2163. 

1431. 

698. 

-34. 

0.0 2596.0 5192.0 7788.0 


Figure 9b. The cross-variogram of primary and 

secondary variables for area-1. 

The sampling interval can be determined based on the semivariograms. In Fig. 9a & 9b, an 

exponential model of isotropic variogram was fitted for the secondary variable (ETM LG 6) 

using an iterative procedure developed by Goulard (1989). The cross-variogram between the 

primary and secondary data sets is modeled (here a small nugget effect 11.6m and a spherical 

model with sill 232.2m and range 3400.0m), indicating that the intensive sampling scheme 

used resolved most of the spatial variation 

Nevertheless, Fig. 10a & 10b illustrate the experimental semivariograms of the 

secondary variable (ETM LG 6) and the cross-variogram in study area-2. At area-2, the 

isotropic varigram of (ETM LG 6) shows a spherical model with a sill of 164.7m and a fitted 

range of 1150.0m, which probably reflected gradual differences in EC due to elevation. The 

cross-variogram between the primary and secondary data sets in area-2 modeled linearly with 

sill of 0.1m and range of 0.75m. Although in study area-2, EC was less significantly 

correlated with the secondary variable compare with area-1, only a small portion of the 

variation in EC can be explained by variation in elevation. 

Generally, cross-variograms largely confirmed the findings of the simple correlation analysis, 

showing (i) more spatial correlation between EC and ETM LG 6 at area-1, and (ii) declining 

spatial correlation between EC and ETM LG 6 at area-2 (Fig. 10b). This proves the existence 

of correlation between spatial variability of the soil salinity data, which belongs to nugget 

effect. 

Semivariance 

450.0 

300.0 

150.0 

"ETM LG 6" Isotropic Variogram 

0.0 

0.0 2257.7 4515.3 6773.0 


Figure 10a. The semivariogram of secondary 

variable for study area-2. 

Semivariance 

"EC" x "ETM LG 6" : Isotropic Cross Variogram 

1552.79 

851.66 

150.52 

-550.61 

-1251.75 

0.00 2257.67 4515.33 6773.00 


Figure 10b. The cross-variogram of primary and 

secondary variables for area-2.


Colocated Cokriging of EC point observations with ETM as secondary data source 

The colocated cokriging interpolated maps cover study areas 1 and 2 is shown in Fig. 11a & 

12a. The ordinary cokriging algorithm was applied to interpolate the EC data using GS + 

program. 

As a result of using search neighborhood area as indicated in the cross-variograms of 

area-1 and area-2, quite lots of areas were closed to the primary observation points and this 

give high effect of the secondary data. Closer to primary observation points this effect is 

more screened by the available primary data and this significantly improved the accuracy of 

colocated EC maps. 

However, the visual interpretation of the EC colocated map of area-1 in relation to the 

DEM (digital Elevation Model) grid image of each area give a good impression that the 

estimation of salinity values is logical, taken into consideration the location from the salt 

effected soils (playa), the relatively lower elevation units (depressions) and the position in 

landscape in the oasis (Fig. 11b). 

"m north" 

3142286 

3138434 

3134583 

35679444 35687159 

"m east" 

35694874 

Figure 11a. Interpolate-colocated cokriging map of EC (dS/cm) of the study area-1 (North of 

Bahariya). 

On the other hand, the relatively high ECe (dS/cm) values that are pronounced and 

presented as connected counter lines are expressing the areas where low elevation and much 

salinity features are available. This is clear presented for area-2 in Fig. 12b. This quite 

validating the estimated interpolated cokriged maps obtained. Obviously, there is a visually 

better resolution of spatial detail in the EC colocated cokriging interpolated maps. 

237 

"EC" 

> 164 

> 151 

> 139 

> 126 

> 114 

> 102 

> 89 

> 77 

> 64 

> 52 

> 39 

> 27 

> 15 

> 2 

> -10


3142000 

3140000 

3138000 

3136000 

"m north" 

35680000 35684000 35688000 35692000 

3103869 

3100634 

Playa 

238 

Playa 

Depression 

Figure 11b. The Digital Elevation Model (DEM) map of area-1. 

3097399 

35657997 35663986 

"m east" 

35669976 

"EC south area" 

Figure 12a. Interpolate-colocated cokriging map of EC (dS/cm) of the study area-2 (South of 

Bahariya). 

3102000 

3100000 

3098000 

35658000 35661000 35664000 35667000 

Playa 

Figure 12b. The Digital Elevation Model (DEM) map of area-2 

142 

138 

134 

130 

126 

122 

118 

114 

110 

106 

102 

98 

94 

144 

140 

136 

132 

128 

124 

120 

116 

112 

108 

104 

100 

96 

92 

> 119 

> 110 

> 102 

> 93 

> 85 

> 77 

> 68 

> 60 

> 51 

> 43 

> 34 

> 26 

> 18 

> 9 

> 1


Perform cross validation analysis 

To assess the accuracy of the colocated cokriging estimated maps, there is a cross validation 

analysis for evaluating effective parameters for cokriging. In cross-validation analysis a graph 

can be constructed of the estimated vs. actual values for each sample location in the domain. 

The cross validation analysis of study areas 1 and 2 are presented in Fig. 13a & 13b. Each 

point on the graph represents a location in the input data set for which an actual and estimated 

value are available. 

Actual "EC" 

178.00 

133.74 

89.48 

45.22 

0.96 

0.96 59.97 118.99 178.00 

Estimated "EC" 

Regression coefficient = 0.321 (SE = 0.363 , r2 =0.026, 

y intercept = 26.72, SE Prediction = 45.893) 

Figure 13a. Cross Validation (CoKriging) of 

study area-1. 

239 

Actual 

132.00 

99.22 

66.43 

33.65 

0.86 

0.86 44.57 88.29 132.00 

Estimated 

Regression coefficient = -0.455 (SE = 0.390 , r2 =0.102, 

y intercept = 75.99, SE Prediction = 37.344) 

Figure 13b. Cross Validation (CoKriging) of 

study area-2. 

The regression coefficient, which is describing the linear regression equation is for 

(area-1) = 0.3 and for (area-2) = -0.4. The standard error of the regression coefficient (SE = 

0.36, 0.39 for area-1 & 2 respectively). The r 2 value is the proportion of variation explained 

by the best-fit line (in case of (area-1) = 2.6% and 10.2% for (area-2)); and the y-intercept of 

the best-fit line is also provided. The SE Prediction term is defined as SD x (1 - r 2 )0.5, where 

SD = standard deviation of the actual data (45.9 and 37.3 for areas-1 & 2 respectively). 

Generally, the method of colokated cokriging significantly improved the accuracy of 

interpolated cokriged EC maps, as shown by a reasonable acceptable regression coefficient 

values in both study areas. For cokriged EC, patterns in the interpolated EC maps closely 

resembled those of the DEM maps, indicating that this method is also more vulnerable to 

potential artifacts in ancillary variables. In study areas 1 & 2, both the primary variate (ECe 

measurements) and secondary one (surface reflectance derived from ETM satellite image) 

contributed significantly to predicting the local means of ECe. 

However, it is clear that the spatial variability of area-2 is comparatively less than that 

in area-1. The main reason for this weakness of spatial variability in area-2 could be referred 

to the lack of EC sampling points available and still to the high influence of the ECe (dS/cm) 

extreme values on neighboring locations. 

Although two sites were used in our study, the range in soil types and terrain conditions 

was limited. Clearly, more work needs to be done, to develop a flexible, more generic 

framework for soil salinity mapping at different scales and in different environments. Of 

particular interest is what secondary data source (e.g. surface reflectance derived from 

satellite images) are most suitable for EC mapping across larger regions, for which detailed 

on-the-go mapping of EC or similar properties is not feasible. Our study indicates great 

potential for reducing sampling demand in digital soil salinity mapping when a cokriging 

approach is used. However, the reduction of sample size tested here (Fig. 13a & 13b) was 

somewhat arbitrary. Better procedures are needed for optimizing sampling with regard to


covering the variation in primary and secondary variables in both feature and geographic 

spaces, including situations where little prior information about the target variable is 

available. 

CONCLUSION 

The spatial distribution maps drawn based on cokriging interpolation method explain clearly 

the spatial variability of soil salinity in north and south study areas of Bahariya oasis. 

Geostatistical method of colocated cokriging that utilized spatially correlated secondary 

information increased the quality of maps of soil salinity (ECe measurements) as compared to 

ordinary kriging method. Apparent EC cokriged with surface reflectance derived from 

satellite images performed best in terms of increasing map accuracy. In this method, relative 

improvements in map accuracy over ordinary kriging method ranged from 19% to 38% at the 

two study areas and there was little loss of accuracy when sampling intensity was reduced by 

half as shown in area-2. The ETM LG band 6 secondary data source is considered valuable 

one for detailed mapping of EC at the field scale, whereas the relative value of terrain 

attributes varied geographically. 

Indeed, there are different original factors have influenced the final output of the 

cokriging logarithm technique. Those factors can be related to the issues of sampling, the 

spatial distribution of the soil salinity measurements in the space, the total number of the 

observation points and the variability of the ECe data set obtained. In addition, most 

secondary information (i.e. satellite image data) contains uncertainties that may mask 

relationships with EC values, or other soil properties of interest. Furthermore, relying on a 

single secondary attribute is risky because (i) the variable chosen may not be related to the 

primary variable of interest and (ii) field artifacts or errors in the secondary information could 

cause significant errors in the EC prediction. 

Improving those factors especially in the south study area-2, would play an important 

role for receiving more accurate results out of this interpolation method. 

At the end of the whole procedure, it is still manage successfully to use the obtained 

interpolated EC salinity maps. To reduce uncertainties, we recommend using independently 

measured, multivariate secondary information in estimating spatial variability of soil salinity 

approach. 

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241


SPATIAL VARIABILITY OF DRAINAGE AND PHOSPHATE 

RETENTION AND THEIR INTER RELATIONSHIP IN SOILS OF 

THE SOUTH-WESTERN REGION OF THE NORTH ISLAND, 

NEW ZEALAND 

A.Senarath*, A.S.Palmer and R.W.Tillman 

Soil & Earth Sciences, Institute of Natural Resources, Massey University, Palmerston North, New Zealand 

Abstract 

Spatial variability of drainage, phosphate retention and their inter-relationship was 

investigated in soils developed from mixed quartzo-feldspathic and tephric parent material on 

river terraces in the south western region of the North Island . A series of drainage class maps 

at 1:25,000, 1:10,000 and 1:5000 scales were produced for selected window areas. The 

optimal soil mapping scale for capturing soil drainage variability and the usefulness of the 

soil maps for identifying spatial variability of phosphate-retention was investigated. Soil 

drainage varies from well drained through moderately well drained to imperfectly drained 

and poorly drained within a paddock scale (2-3 ha). In this study, soil drainage had no 

topographic control which makes soil mapping extremely difficult. The reason for the short 

distance variability in drainage is attributed to slight textural variations of the original alluvial 

parent material. This gives rise to the formation of different soil structures, which in turn 

influences the hydraulic conductivity of the soil and results in variable drainage properties 

which influence the clay mineralogy. There is a close relationship between soil drainage, Pretention 

and clay mineralogy. Well drained soils have high P-retention and the clay fraction 

contains 12-13% allophane. Poorly drained soils have low P-retention and the clay fraction 

has no allophane and contains mainly kandite. The relationship between soil drainage and Pretention 

can be used to identify different P-retention areas on soil maps. In addition, 

1:10,000 is the most suitable soil mapping scale for practical farm planning in the Region. 

INTRODUCTION 

A detailed soil survey carried out at 1:25,000 scale in an area covering 2000 ha of terraced 

land near Kiwitea village in south western region of the North Island reveals that the soil 

drainage varies over the landscape at paddock scale (2-3 ha.) having no topographic control 

[15]. Soil drainage dictates suitability for cropping and intensive grazing and sensitivity of 

land to a number of management practices so, soil drainage class maps will be helpful in land 

use planning and management practices. Furthermore previous studies have shown that 

phosphate retention (P-retention) is related to soil drainage; and in particular Parfitt et all[10] 

have shown that soil drainage influences clay mineralogy and hence P-retention. Phosphate 

retention is an important soil attribute determining the amount of P needed to be applied for 

plant production. Soil maps are therefore valuable tools. Small scale existing soil maps 

published for the area at 1:250,000 [9] and at 1:63,360 [8] are clearly incapable of showing 

drainage variability on soil maps [15]. 

The aim of this study is to investigate variability of soil drainage status over the 

landscape, the best scale to map soil drainage classes to aid land management decisions, 

242


ability of soil drainage class maps to predict P-retention values and the reasons for short 

distance soil drainage variability in the region.. 

OVER VIEW OF THE STUDY AREA 

The study area, 2000 ha in extent, is located near Kiwitea village in the northern Manawatu 

district which is situated towards the south-western part of the North Island. The landform of 

the area is characterized by suites of river terraces at different elevations. Three major 

terraces can be identified within the area; the river flats (180 m above msl) covered with 

recent alluvium (1000-2000 years BP) having flat to gently sloping topography, the 

intermediate terrace (200-240 m above msl) covered with a mixture of old alluvium, 

colluvium, loess and tephra (


core sampler and were combined to form a composite sample to determine P-retention. This 

is the methodology used in New Zealand as part of a fertiliser recommendation for pastures. 

P-retention of soils was determined according to the method given by Saunders [13] 

and the results are expressed as percentage values. Eight quality control samples with known 

P-retention values were incorporated within each 100-sample batch to monitor the possible 

variations that might arise among different batches. The same P-retention solution and 

vanado-molybdate solutions were used throughout the analysis of the samples for a fair 

comparison of results. 

Preparation of maps 

Drainage class maps were generated by the “Surfer” programme (version 5.0) based on the 

point drainage class data. The drainage class maps (Figure 3A, 3B and 3C) are contour maps 

generated by the “Surfer” programme based on the point drainage data. The programme 

generates values between the points automatically by kriging [14]. To generate maps, 

drainage classes were given numerical values of 100, 90, 60 and 30 for well drained, 

moderately well drained, imperfectly drained and poorly drained drainage classes 

respectively [6]. When generating the contour pattern, the programme always generates a 

sequential drainage pattern according to this order. That is if a well drained soil was found by 

augering to occur adjacent to a poorly drained soil, the programme automatically interpolates 

moderately well drained and imperfectly drained soil units between the two.A series of soil 

drainage class maps were produced at 1:25,000 (observations on a 250 m grid), 1:10,000 

(observations on a 100 m grid) and 1:5000 (observations on a 50 m grid) scales 

Bulk density 

Bulk density measurements were made on core samples (with known volume) taken from 

each soil horizon. Soil samples were oven dried at 105° C until the weight became constant. 

Saturated hydraulic conductivity (Ksat) 

Saturated hydraulic conductivity measurements were made for undisturbed soil samples taken 

from each soil horizon, using intact cores (150 mm height and 74 mm diameter) according to 

the method of Klute [5]. 

Mineralogical analysis 

Mineralogical properties of soil samples were determined according to methods described by 

Whitton and Churchman [18]. Allophane present in soils was determined according to the 

method of Parfitt [11] and Parfitt and Wilson [12]. Acid-oxalate extractable Si was 

determined according to the method of Blakemore et.al..[1]. 

Soil drainage variability 


The 1:250,000 scale soil map [9], of the study area portrays the 2000 m by 300 m window 

area as well drained, Kawhatau silt loam (Table 1). A subsequent land resource map at 

1:63,360 scale [8] shows the area to be well drained, Kiwitea loam. Senarath [15] has 

244


explained why neither series name is appropriate for the soils on the Intermediate terrace, and 

introduced new series. When the authors mapped the area at 1:25,000 scale it appears to 

encompass three different soil drainage classes (Figure 1a); well drained, Coulter silt loam, 

moderately well drained, Horoeka silt loam and imperfectly drained, Barrow silt loam (Figure 

Figure: 1a Soil drainage class map for the 2000 m by 300 m window area (60 ha) when mapped at 

1:25,000 scale. 

Figure: 1b Grid sampling design (50 m by 50 m) within blocks A, B and C established within the 2000 

m by 300 m large window area on imperfect, moderately well and well drained soil units respectively 

mapped at 1:25,000 scale. 

Figure: 1c .Soil drainage class maps for the 300m by 250m window (7.5 ha) areas when mapped at 

1:10,000 scale. 

Figure: 1d Soil drainage class maps for the 300 m by 250m blocks (7.5 ha) when mapped at 1:5,000 

scale. 

245


Soil type New Zealand Classification 

USDA Soil Taxonomy 

[4] 

[16] 

Kawhatau silt loam Acidic Allophanic Brown Soil Andic Eutrudepts 

Kiwitea loam Typic Orthic Melanic Soil Eutrudepts 

Coulter silt loam Typic Orthic Allophanic Soil Dystrudepts 

Horoeka silt loam Typic Orthic Melanic Soil Andic Eutrudepts 

Barrow silt loam Mottled Immature Pallic Soil Aqualfs 

Table 1:Classification of soil types according to the New Zealand soil classification system and the 

USDA Soil Taxonomy. 

1a). When selected window areas (blocks A, B and C) are mapped at 1:10,000 scale it 

becomes apparent that the relatively simple soil drainage pattern represented in the 1:25,000 

scale map (Figure 1a) is much more complex (Figure 1cA, 1cB, and 1cC). Instead of a 

gradation of drainage status from well drained to imperfectly drained soils (Figure 1a), there 

is a mixture of well, moderately well and imperfectly or poorly drained soils present in each 

block within close proximity. At least three different soil drainage classes are identified in 

each of the 300 m by 250 m blocks when mapped at 1:10,000 scale. Each of these blocks 

comprises only one soil drainage class when mapped at 1:25,000 scale. 

When blocks A, B and C are mapped at 1:5000 scale, no new drainage classes are found 

in any areas except for block B (Figure 1d B), but the drainage class boundaries could be 

shown more accurately and it is apparent that the distribution of drainage classes is more 

complex even than that revealed at 1:10,000 scale (Figure, 1d A, 1d B and 1d C). It is evident 

that when ground observation intensity is increased a more and more variable soil drainage 

pattern can be observed. 

Soil-landscape relationship 

The problem associated with mapping of drainage classes (soil mapping) in this area is that it 

is difficult to establish an obvious relationship between soil drainage and the topography of 

the land [15]. The land is essentially flat to gently undulating, with a gentle tilt to the west. 

There are some instances where soils in local depressions, areas close to water bodies or 

streams are imperfectly or poorly drained, but that cannot be accepted as a general rule for 

the entire area. 

Phosphate retention (P-retention) 

The relationship between soil drainage and P-retention was investigated in detail using soil 

drainage information collected from blocks A, B and C on a 50 m interval grid (Figure 1b). 

The comparison between soil drainage and the P-retention at each observation point indicates 

that 100% of the poorly drained soils in the study area have low P-retention, whereas 100% 

of the well drained soils have high P-retention. P-retention in imperfectly drained soils ranges 

from low through medium to high, but 69% of the observations have medium P-retention. 

Twenty two percent show high values and only 8% show low values. A majority of the 

moderately well drained soils have high P-retention (85%), whereas only 15% of the 

observations have medium P-retention values (Table 2). 

246


Drainage class 

Blocks A+B+C 

Total number of observations 

247 

Blocks A+B+C 

Percentage number of observations 

LP-ret MP-ret HP-ret LP-ret MP-ret HP-ret 

0 - 30% 31 – 60% 61 – 100% 0 -30% 31 – 60% 61 – 100% 

Poorly drained 9 0 0 100 0 0 

Imperfectly drained 4 34 11 82 69.4 22.4 

Moderately well drained 0 5 29 0 14.7 85.3 

Well drained 0 0 34 0 0 100 

Table 2:The relationship between soil drainage classes and P-retention classes. 

LP-ret = low P-retention; MP-ret = medium P-retention; HP-ret = high P-retention. 

From these observations it is evident that poorly drained soils have low P-retention, 

imperfectly drained soils have medium P-retention and moderately well drained and well 

drained soils have high P-retention. Therefore, the variability in P-retention within paddocks 

can be attributed to the variability of soil drainage. The relationship has been suspected but 

never before demonstrated for New Zealand soils. 

Soil drainage, phosphate retention and clay mineralogy 

The sand fractions of both the well drained and imperfectly drained soils on the intermediate 

terrace contain volcanic glass (Table 3). But the clay fraction of the well-drained soils 

contains allophane whereas the clay fraction of the imperfectly drained soils contains no 

allophane. The P-retention also varies accordingly (Table 3). 

Soil Type 

Sand fraction Clay fraction 

Quartz Feldspar Volcanic.glassKandite 

Allophane P- 

% % % 

% % Ret.% 

Coulter silt Well drained 41 32 13 

loam 

16 10 86 

Barrow silt Imperfectly 54 29 8 

loam drained 

31 0 50 

Table 3.The relationship between soil drainage, P-retention and clay mineralogy of the topsoil of two 

of the soils (Senarath, 2003). 

As mentioned in the introduction, Parfitt et al. [10] showed that clay mineralogy is 

related to soil drainage. It is well known in New Zealand that topsoils dominated by 

allophane have high P-retention while those dominated by kandite have low P-retention. 

These results show that the average P-retention of the topsoil is also influenced by the 

drainage of the whole profile. 

Soil mapping scale and variability of P-retention 

The P-retention values of the topsoil samples collected from the study area range from 15% 

to 86% [15]. These values indicate that there is considerable variability in P-retention within 

the soils, ranging from low to high [13]. When the area is mapped at 1:25,000 scale, the 

ranges of P-retention within the imperfectly, moderately well and well drained map units, are 

15-72%, 23-86% and 34-86% respectively (Table 4). These figures show that the variability


within each map unit at this scale has not reduced significantly compared to the total range of 

P-retention (15 – 86%). 

Map unit 

Mapping scale 1:25,000 

Phosphate Retention 

Range Mean STD CV% 

Ohakea silt loam (PD) No mapping unit at 1:25,000 scale 

Barrow silt loam (ImD) 15 - 72 44.1 14.4 32.6 

Horoeka silt loam (MWD) 23 - 86 65.1 14.2 21.8 

Coulter silt loam (WD) 34 - 86 71 12.4 17.4 


Ohakea silt loam 22 - 44 28 6.7 23.9 

Barrow silt loam 15 - 73 46.2 13.5 29.2 

Horoeka silt loam 23 - 86 64.8 13.8 21.2 

Coulter silt loam 54 - 86 75.9 6.1 8 


Ohakea silt loam 16 - 52 27.5 8.3 22.3 

Barrow silt loam 15 - 78 48.5 14 28.8 

Horoeka silt loam 32 - 85 67.9 10.4 15.3 

Coulter silt loam 54 - 86 76.7 5.9 7.6 

Table 4:The variability of P-retention within the soil map units when mapped at three different scales. 

(Senarath, 2003). 

STD = standard deviation; CV% = coefficient of variation; PD = poorly drained; ImD = imperfectly 

drained; MWD = moderately well drained; WD = well drained 

When the mapping scale is increased from 1:25,000 to 1:10,000 a new poorly drained 

map unit (Ohakea silt loam) with less variable P-retention values (22 – 44%) is added to the 

soil map (Table 4). The range of P-retention values in the Barrow (15 – 73%) and Horoeka 

(23 – 86%) map units changed only slightly. However, there is a considerable change of 

range in P-retention within the Coulter map unit (from 34 – 86% to 54 – 86%). The coefficient 

of variation (CV) indicates that Barrow and Horoeka map units mapped at 1:10,000 

scale are slightly less variable compared to that of 1:25,000 scale. CV of P-retention slightly 

reduced in Barrow (from 32.6 to 29.2%) and Horoeka (from 21.8 to 21.2%) silt loams 

whereas CV considerably reduced in Coulter silt loams (from 17.4% to 8%) (Table 4). 

When the mapping scale increased from 1:10,000 to 1:5,000, the variability of Pretention 

very slightly decreased in Ohakea , Barrow, Horoeka and Coulter silt loam map 

units (Table 4). 

Therefore map units at all scales have a considerable range in P-retention, but their 

mean P-retention values increase in an orderly manner with improving drainage. 

Soil maps at 1:25,000 scale are of little use in identifying different areas of P-retention 

in the field. Drainage class maps at 1:10,000 scale can be used to identify low and high Pretention 

areas successfully, but always some uncertainty exists within moderately well and 

imperfectly drained areas. Although 1:5000 scale maps are more precise and less variable, 

there is no advantage in using them instead of 1:10,000 maps when the added cost of 

producing the maps at the larger scale is taken into account. 

248


Genesis of soil drainage conditions 

Soil texture is a property that is initially inherited from its parent material, so variations in 

soil texture are presumed to reflect variations in initial deposition overprinted by changes due 

to weathering. 

The slight textural variations in the parent material probably effected slight variations 

in soil structural development. In the soils of the study area, silt loam soil textures are 

associated with nutty structure while silty clay loam; clay loam or clay soil textures are 

associated with blocky structures (Table 5 and 6). 

Horizon Depth (cm) Field -texture Structure Macro- 

Porosity (%) 

249 

Ksat 

(mm hr –1 ) 

Ap 0-20 silt loam moderate fine to medium nutty 6 to 7 8 

Bw1 20-65 silt loam moderate fine to medium nutty 11 8 

Bw2 65-95 silt loam moderate fine to medium nutty 

and moderate medium blocky 

2Ab 95-125 clay loam moderate medium to coarse 

blocky 

8 4.3 

5 4.6 

Table 5:The physical properties of a representative profile of well drained Coulter silt loam related to 

water movement in soil (Senarath, 2003). 

Horizon Field-texture Structure Macro- Ksat 

depth (cm) 

porosity (%) (mm hr –1 ) 

Ap 0-21 silt loam Strong fine to medium nutty 4 to 8 6.4 to 14 

Bg1 21-34 silty clay loam strong very fine, fine and medium 

nutty and moderate medium blocky 

Bg2 34-65 fine sandy clay loam strong medium to coarse 

nutty 

Bg3 65-82 clay loam moderate medium to coarse 

blocky 

12 0.9 

9 7.6 

3 0.8 

Table 6:The physical properties of a representative profile of imperfectly drained Barrow silt loam 

related to water movement in soil (Senarath, 2003). 

It is hypothesised that the differences in soil structure largely caused the differences in 

drainage status. The hydraulic conductivity of a soil is directly related to its porosity, more 

importantly the macro porosity. The shape and the size of the soil structural units has a 

noticeable affect on the space between them [2,3] Blocky structure is more closely fitting 

than nutty structure hence water can move more readily along structural faces of soils having 

nutty structure. 

Saturated hydraulic conductivity (Ksat) values in the Bg1 and Bg3 horizons (0.9 and 

0.8 mm/hr) are very slow in the imperfectly drained Barrow soils (Table 6). This impedes 

drainage in the whole profile. K sat values for the other two horizons are approximately same 

as that of the Coulter soil (Table 5). Ksat values range from moderately slow to very slow in 

soils having blocky structures [3] Although macro porosity is more or less similar to that of 

Coulter soils (Table 5), they may not be interconnected within soil aggregates, because


blocky structure is rather compact compared to nutty structure [3]. Therefore, water moves 

very slowly within Barrow soils, creating imperfect drainage conditions. 

The soil textures of Coulter soils are silt loam and the structures are nutty. The 

structural units are not closely packed as explained above. Therefore, water can move 

through soils more rapidly and hence soils are well drained. 

From these observations it is possible that the drainage variability of soils within short 

distances on the intermediate terrace may be associated with the slight textural variations of 

the original alluvial parent materials from which the soils are formed, and the resulting 

development of contrasting soil structure. These subtle changes in texture have been 

subsequently masked by weathering including clay formation and changes in clay 

mineralogy. 

Soil drainage conditions influence clay mineralogy. According to Parfitt et al. [10] 

weathering of rhyolitic tephra is controlled by Si in soil solution. When Si concentration in 

the soil solution is low (possibly < 10 µg cm -3 ), due to leaching, allophane is formed from 

volcanic glass whereas if Si concentration is high (possibly >10 µg cm -3 ), in the soil solution 

due to impeded drainage conditions, halloysite is formed. The presence of allophane in the 

clay fraction of Coulter silt loam can be attributed to weathering of volcanic glass under welldrained 

conditions. Under well-drained conditions Si is leached from the profile and 

allophane forms. Imperfectly drained Barrow silt loam contains no allophane in the clay 

fraction due to Si not being leached from the profile, and kandite minerals (kaolinite + 

halloysite) form instead. 

The variability in P-retention within a paddock should have a significant influence on 

the amount of phosphate fertilizer applied by farmers. If fertilised at a rate suited to the low 

P-retention soil, then the high P-retention soils in the paddock will be deficient in P and will 

have suboptimal productivity. If land is fertilised according to the high P-retention soil, then 

surplus P will be applied to the low P-retention soil which is uneconomic and may increase 

the rate of loss of P to waterways. Thus it is clear from both an economic and an 

environmental point of view that soils within different P-retention classes should be treated 

differently. Therefore, identification of low, medium and high P-retention areas in the 

landscape and managing them accordingly is important. Variable rate of application of 

phosphate fertiliser through precision agriculture is an obvious solution, if the areas of low, 

intermediate and high P-retention in a paddock can be identified. This is most cheaply and 

efficiently achieved by soil survey recognising drainage classes. 

CONCLUSIONS 

• Soil drainage properties in the study area vary from well drained through moderately well 

drained to imperfectly drained and poorly drained with in the paddock scale. 

• The poor relationship between soil drainage and the topography of the landscape poses 

difficulties for conventional soil survey. 

• There is a strong relationship between soil drainage, phosphate retention and clay 

mineralogy in soils developed from tephra mixed parent materials. Well drained soils 

have high P-retention and the clay fraction contains allophane whereas poorly drained 

soils have low P-retention and the clay fraction contains no allophane but mainly kandite. 

• The positive relationship between soil drainage and P-retention can be used to identify 

different P-retention areas on soil maps. 

• 1:10,000 is the optimal soil mapping scale for practical farm planning in this area. 

250


• Short distance drainage variability has a relationship to the textural variations of the 

original alluvial parent material which gives rise to the formation of different soil 

structures and different pathways of weathering. This in turn influences the hydraulic 

conductivity of the soil and results in variable drainage conditions and different Pretention 

values. 

REFERENCES 

[1] L.C.Blakemore, P.L.Searle, B.K.Daly. Methods for chemical analysis of soils, New Zealand Soil Bureau 

Scientific Report no.80, .New Zealand Society of Soil Science, Lower Hutt, New Zealand, (1987). 

[2] E.Griffiths, T.H.Webb, J.P.C.Watt, P.L.Singleton. “Development of soil morphological descriptors to 

improve field estimation of hydraulic conductivity”, Australian Journal of Soil Research, 37, PP. 971-982, 

(1999). 

[3] E.Griffiths. Interpretation of soil morphology for assessing moisture movement and storage, New Zealand 

Soil Bureau Scientific Report, 74, (1985). 

[4] A.E.Hewitt. New Zealand Soil Classification, DSIR, Land Resources Scientific Report No.19,(1992). 

[5] A.Klute. Methods of soil analysis part 1, American Society of Agronomy Inc., Soil Science Society of 

America, Inc., PP. 694-696, (1986). 

[6] J.D.G Milne, B.Clayden, P.L.Singleton, A.D.Wilson. Soil Description Handbook, Lincoln, Canterbury, 

New Zealand, (1995). 

[7] New Zealand Meteorological Service. Summaries of climatological observations to 1980, New Zealand 

Meteorological Service Miscellaneous Publication 177, Ministry of Transport, (1983). 

[8] New Zealand Land Resource Inventory Work sheet, Feilding N.144. The National Water and Soil 

Conservation Organization, Water and Soil Division, Ministry of Works and Development, (1979). 

[9] New Zealand Soil Bureau General survey of the soils of North Island, New Zealand, New Zealand Soil 

Bureau Bulletin 5, (1954). 

[10] R.L.Parfitt, M.Saigusa, D.N.Eden. “Soil development processes in an Aqualf-Ochrept sequence from loess 

with admixtures of tephra”, New Zealand .Journal of Soil Science, 35, PP. 625-640,.(1984). 

[11] R.L.Parfitt. Towards understanding soil mineralogy III, Notes on allophane. New Zealand Soil Bureau 

Laboratory Report CM 10, (1986). 

[12] R.L.Parfitt, A.D.Wilson. Estimation of allophane and halloysite in three sequences of volcanic soils, New 

Zealand, Catena Supplement 7, PP. 1-8, (1985). 

[13] W.M.H.Saunders. “Phosphate retention by New Zealand soils and its relationship to free sesquioxides, 

organic matter and other soil properties”, New Zealand Journal of Agricultural Research, 8, PP. 30-57, (1965). 

[14] A.Senarath, G.Arnold, A.S.Palmer, R.W.Tillman, M.P.Tuohy. Use of geostatistics in soil mapping for 

precision agricultural management, In precision tools for improving land management (Eds LD Currie and P 

Loganathan).Occasional report No.14.Fertiliser and Lime Research Centre, Massey University, Palmerston 

North, PP. 161-171, (2001). 

[15] A.Senarath. Soil spatial variability in northern Manawatu, New Zealand, Unpublished PhD thesis, Massey 

University, Palmerston North, New Zealand, (2003). 

[16] Soil Survey Staff Soil Taxonomy. A Basic System of Soil Classification for Making and Interpreting Soil 

Surveys., United State Department of Agriculture, Agriculture Handbook Number 436, Washington D.C., 

(1999). 

[17] N.H.Taylor, I.Pohlen. Classification of New Zealand Soils, In Soils of New Zealand, Part 1 (Ed Jean Luke) 

PP. 15-46, New Zealand Soil Bureau Bulletin. 26(1), (1968). 

[18] J.S.Whitton, G.J.Churchman. Standard methods for mineral analysis of soil survey samples for 

characterization and classification in New Zealand, New Zealand Soil Bureau Scientific Report 79, (1987). 


The authors are grateful to the technical staff of the Fertilizer and Lime Research Centre, 

Massey University, Palmerston North particularly Ian Furkert, Bob Toes, James Hanly and 

Lance Currie for help in the field and laboratory experiments and farmers of the Kiwitea 

study area for their co-operation during the soil survey and field experiments. 

251


WORKSHOP Theme: Soil survey and inventory techniques 

Convenors: P. Finke, M. Van Meirvenne, R. Goossens 

CONCLUSIONS 

This workshop focused on current and developing techniques for soil and terrain inventory to 

meet requests for the construction, updating and upgrading of soil information systems. The 

papers were grouped into three perspectives: 

1. Soil (attribute) mapping at regional and national scales 

The keynote by Finke addressed the quantitative soil mapping methods coined as digital soil 

mapping methods. Based on the overview it was concluded that these methods have a great 

potential for mapping soil types and soil attributes in scarcely visited areas if ancillary data 

like DTM and remote sensing images are available. As these methods give an indication of 

the precision of their output, they allow for a motivated choice on the positioning of future 

field work. Because of their complexity, applucation of these methods require an expert. It 

was stressed that the resulting maps and data bases are as reliable as the (amount and quality) 

of the data used as input. 

The paper by Wandahwa et al. treated the issue of how to obtain soil characteristics for land 

evaluation in a case study from Kenyia. A comparison was made between the approaches 

“calculate first, interpolate later” and its opposite. It was found that soil characteristics 

respond differently when subjected to interpolation. Conclusion was, that a combination of 

landscape and soil characteristic maps derived from interpolation gave better distribution of 

suitability classes than the approach based directly on soil units. The study successfully 

demonstrates the potential of using GPS and GIS for land evaluation. 

2. Gis and remote sensing 

The keynote by Goossens highlighted a number of important developments in remote sensing 

for data users worldwide. It was concluded that in the near future, 3-D visualisation of remote 

sensing images will become accessible since data and techniques are available and costs are 

low (e.g. the Corona images at $18 / 14*188 km). Another trend is that ground resolutions are 

becoming increasingly finer (± 1.2-1.8 m to near the physical threshold of 30 cm). Thirdly, 

the emergence of hyperspectral imagery (from the Chris-Proba satellite) was mentioned. 

The paper by El-Badawi on mapping soils in southeastern Egypt in difficult field 

circumstances demonstrated that aerial photo interpretation in combination with remote 

sensing is a powerful method to make a physiographic soil map. 

252


3. Soil sampling at field scale 

The keynote by Van Meivenne addressed some developments in soil sampling and proximal 

sensing with applications in precision agriculture. The measurement precision of position (by 

GPS) and crop yield has greatly improved over recent years, is operational and commercially 

available. One bottleneck is the characterization of the within field variability of crop 

controlling variables, especially soil. Usage of soil sensors based on the principle of 

electromagnetic induction (EMI) offers a promising alternative to detailed soil maping and 

intensive sampling schemes. In the context of precision agriculture, it was concluded, that the 

within-field soil variability is often underestimated, especially of deeper soil horizons. There 

is a potential for improved crop management with a reduced environmental pressure. 

253

Workshop IC-PLR 2006 – Theme E – Soil processes and analytical techniques 

WORKSHOP THEME E – SOIL PROCESSES AND ANALYTICAL 

TECHNIQUES 

Sub-theme : Development in soil genesis and mineralogy 

Van Ranst E., Mees F. 

Paper/poster : Impact of acid deposition on cation leaching from Mt. Talang 

airfall ash – D. Fiantis, Nelson, E. Van Ranst, J. Shamshuddin 

Paper/poster : Stone lines and weathering profiles of ferrallitic soils in 

Northeastern Argentina – Morrás H., Moretti L., Piccolo G., Zech, W. 

Paper/poster : Pedogenesis along a hillslope traverse in the upper Afram 

basin, Ghana – T. Adjei-Gyapong, E. Boateng, C. Dela Dedzoe, W.R. 

Effland, M.D. Mays, J.K. Seneya 

Paper/poster : Influence of titanomagnetite on dithionite-citrate-bicarbonate 

(DCB) and oxalate extractions in weathered dolerite – C.G. Algoe, E. Van 

Ranst, G. Stoops 

Sub-theme : Developments in soil micromorphology 

G. Stoops, V. Marcelino, F. Mees 

Paper/poster : Spheroidal weathering of dolerite in Suriname : evidence from 

physical, chemical and mineralogical data – C.G. Algoe, E. Van Ranst, G. 

Stoops 

Paper/poster : Micromorphological characteristics of andisols in West Java, 

Indonesia – Mahfud Arifin, Rina Devnita 

Paper/poster : Micromorphological features of some soils in the Afram 

plains (Ghana, West Africa) – M.D. Mays, W.R. Effland, T. Adjei-Gyapong, 

C.D. Dedzoe, E. Boateng 

Conclusions 

254


Sub-theme : DEVELOPMENTS IN SOIL GENESIS AND 

MINERALOGY 

Overview of latest research in soil genesis and soil mineralogy conducted at the 

Department of Geology and Soil Science 

Van Ranst E. & Mees F. 

Department of Geology and Soil Science, Ghent University, Gent, Belgium 

The research related to mineral weathering/formation and soil processes is concentrated within 

three big research programs that are still going on: 

(1) Interaction between atmospheric deposition, soil acidification, and mineral weathering, using 

soil solution analyses, laboratory and field experiments; 

(2) Mineralogy and chemistry of variable charge soils to determine their constraints and 

management options; and 

(3) Formation of authigenic minerals in atmospheric conditions, studied by means of an analysis 

of regional variations. 

In the first research programme a fortnightly monitoring of the chemical composition of the 

bulk precipitation, throughfall, humus water and soil water at three depths in 6 forest ecosystems 

in Flanders (N-Belgium) is carried out from 1993 onwards. The selected forest plots, with soils 

ranging from sand to silt of Pleistocene origin, belong to the forest condition monitoring 

programme that started in Flanders in 1987, as part of the ‘International Co-operative 

Programme (ICP) on the Assessment and Monitoring of Air Pollution Effects on Forests’ under 

the Convention of Long-range transboundary Air pollution (UN/ECE) and the European Scheme 

on the Protection of Forests against Atmospheric Pollution. Based on chemical and mineralogical 

analyses a methodology to assess the total acid-neutralizing capacity (ANC) of forest soils has 

been developed and applied on the forest floor and the mineral topsoil in the 6 forest ecosystems. 

As the total ANC is clearly related to the soil texture class, the existing soil maps are ideal 

documents to assess the sensitivity of the soils for acidic pollution. Considering the average acid 

loads on the plots a danger for further aluminization of the organic complexes would be real. 

Although since these analyses did not consider the neutralizing effect occurring during turn-over 

of organic matter, the actual outlook is probably less dramatic. The chemical analyses of the 

monitoring programme proved that previous and present weathering is predominantly due to 

synthesis of HNO3 out of organic remains and subsequent reaction with silicates with release of 

Al 3+ and acidity. The influence of the synthesis of HNO3 on the nutrient replenishment in these 

forest soils has been studied as well. The weathering of soil minerals was studied further in detail 

using different approaches(batch-, column and field experiments). The laboratory experiments, 

performed under different conditions (acid type and strength, temperature, solid:liquid ratio, etc.) 

served to better understand the ability and mechanisms of different minerals (hectorite, biotite, 

vermiculite, etc.) to neutralize acidity. The field experiments, based on the test mineral 

technique, were set up under the hypothesis that a residence of the minerals (trioctahedral 

vermiculite and glauconite) in the soil during 4 years, would result in the extraction of quantiable 

amounts of structural elements, rendering it possible to deduct the in situ weathering rates. The 

255


test-mineral(vermiculite) technique was used to distinguish simple acidolysis from acidocomplexolysis 

in a Podzol profile. 

In the second research programme a great deal of time and effort is spent to study the 

chemical behaviour of variable charge minerals and soils, mainly highly weathered soils (Oxisols 

and Ultisols) of the tropics and volcanic ash soils (Andisols), to elucidate different aspects of 

their behaviour. Variable charge soils (VCS) are heterogenous charge systems. The coexistence 

and interactions of soil particles and colloids with net opposite surface charges confer a quite 

interesting, and much more complex pattern with respect to soil physical and chemical behaviour 

compared to homogeneously charged soil systems of temperate regions. Different methods 

(NH4OAc, Charge Fingerprint, Compulsive Exchange) to determine the electrochemical 

properties, in particular ion exchange capacities, have been tested to assess variation in 

exchange capacity with respect to the composition of the colloid fraction. The application of Casilicate 

slags and calc-alkaline pyroclastic materials has been used to increase the cation 

exchange capacity (CEC) of highly weathered VCS. Research using other natural amendments 

on sandy soils is going on at moment. Special emphasis is given to the study of Andisols on 

volcanic ash, mainly from the Indonesian islands, Java and Sumatra. The physico-chemical and 

mineralogical properties of ash soils along the Sunda arc were characterized in order to assess 

the influence of the change of parent material on differing soil characteristics and on surface 

reactivity with emphasis on short-range-order mineral constituents and active Al and Fe 

compounds on fluoride and phosphate sorption. This study provided a scientific basis for (1) 

localizing the soils which are less likely to be deficient in Ca and Mg under yearly application of 

acidifying nitrogenous fertilizers and (2) proposing separate regions in terms of P-fertilizer 

strategy for sustainable crop production. 

The aim of the third research programme is to contribute to a fundamental understanding 

of the factors and mechanisms that control the formation of authigenic minerals at earth-surface 

conditions. Specific objectives are (i) an evaluation of the conditions of formation of authigenic 

minerals for individual lake basins in selected study areas, and (ii) the creation of a regional 

synthesis for each study area, relating variations in the nature and mode of occurrence of 

authigenic minerals to regional patterns and factors. One of both regions selected for this research 

project is a zone with temporary and dry salt lakes in a karst area of the Ebro Basin in northern 

Spain (Los Monegros), with e.g. abundant gypsum, magnesite, halite and Mg-bearing sulfates. 

The second study area is a region with dry lake basins in the southwestern Kalahari, Namibia, 

which contain smectite, sepiolite, dolomite, thenardite and various other authigenic minerals in two 

previously studied basins. The lakes in both regions represent a series of mainly groundwater-fed 

flow-through basins. Both study areas contain a group of about 20 isolated lake basins, 

characterised by (i) the presence of authigenic minerals belonging to different mineral groups, (ii) 

differences in mineral associations between the basins, and (iii) important variations within the 

individual basins, which represent a set of characterstics that renders the study areas ideally suited 

for investigating the conditions of authigenic mineral formation. These conditions will initially be 

determined for each individual lake basins, considering various modes of mineral formation 

(synsedimentary vs pedogenic, direct precipitation vs transformation) and the processes and factors 

that control mineral distribution patterns (e.g. lateral and vertical groundwater movement, flooding, 

groundwater composition, groundmass characteristics, porosity, lithological discontinuities). 

Subsequently, a regional synthesis for each study area will be made, allowing the development of a 

model for authigenic mineral formation, in relation to the evolution of groundwater composition 

within the region, modified by local factors. Samples were collected in both study areas in the 

256


course of 2005. Analysis of the available samples is in progress, using X-ray diffraction methods, 

thin section observations and chemical analyses. 

REFERENCES 

[123] D. Fiantis, E. Van Ranst, J. Shamshuddin, I. Fauziah, S. Zauyah. "Effect of calcium silicate and 

superphosphate application on surface charge properties of volcanic soils from west Sumatra, Indonesia". Comm. 

Soil Sci. Plant Anal., 33: 1887-1900, (2002). 

[124] P. Kanyankogote, E. Van Ranst, A. Verdoodt, G. Baert. "Effet de la lave trachybasaltique broyée sur les 

propriétés chimiques de sols de climat tropical humide", Etude et Gestion des Sols, 12(4):301-311, (2005). 

[125] O.T. Mandiringana, P.N.S. Mnkeni, Z. Mkile, W. Van Averbeke, E. Van Ranst, H. Verplancke. 

"Mineralogy and fertility status of selected soils of the Eastern Cape Province, South Africa". Comm. In : Soil 

Science and Plant Analysis, 36:2431-2446, (2005). 

[126] F. Mees. “Salt mineral distribution patterns in soils of the Otjomongwa pan, Namibia”. Catena, 54:425- 

437, (2003). 

[127] F. Mees, M. De Dapper. “Vertical variations in bassanite distribution patterns in near-surface sediments, 

southern Egypt”. Sedimentary Geology, 181:225-229, (2005). 

[128] F. Mees, A. Singer. “Surface crusts on soils/sediments of the southern Aral Sea basin, Uzbekistan”. 

Geoderma, in press. 

[129] F. Mees, G. Stoops, E. Van Ranst, R. Paepe, E. Van Overloop. "The nature of zeolite occurrences in 

deposits of the Olduvai Basin, northern Tanzania", Clays and Clay Minerals, 53(6) : 659-673, (2005). 

[130] J. Neirynck, E. Van Ranst, P. Roskams, N. Lust. "Impact of decreasing throughfall depositions on soil 

solution chemistry at coniferous monitoring sites in northern Belgium", Forest Ecology & Management, 160:127- 

142, (2002). 

[131] N.P. Qafoku, E. Van Ranst, A.Noble, G. Baert. "Mineralogy and chemistry of variable charge soils. In : 

The Encyclopedia of Soil Science (Ed. : R. Lal), M. Dekker, Inc. (ISBN:0-8247-0846-6)", Online Published:1-8, 

(2003). 

[132] N.P. Qafoku, E. Van Ranst, A.Noble, G. Baert. "Variable charge soils : their mineralogy, chemistry and 

management", Advances in Agronomy, 84:159-215, (2004). 

[133] G. Stoops, E.Van Ranst, K. Verbeek. "Pedology of soils within the spray zone of the Victoria Falls 

(Zimbabwe)", Catena, 46:63-83, (2001). 

[134] E. Van Ranst, F. De Coninck. "Evaluation of ferrolysis in soil formation", European Journal of Soil 

Science, 53:513-519, (2002). 

[135] E. Van Ranst, F. De Coninck. "Synthesis of HNO3 out of organic matter and its influence on weathering. In 

: Soil Science : Confronting New Realities in the 21 st Century", Transactions 17 e World Congress of Soil Science 

(CD-Rom), Bangkok, Thailand : 285, 1-10, (2002). 

[136] E. Van Ranst, F. De Coninck, K. Van Rompaey. "Synthesis of HNO3 from organic matter and its influence 

on nutrient replenishment in forest soils", Environmental Monitoring and Assessment, 98:409-420, (2004). 

[137] Van Ranst, E., De Coninck, F., Roskams, P., Vindevogel, N. "Acid-neutralizing capacity of forest floor and 

mineral topsoil in Flemish forests (North Belgium)", Forest Ecology and Management, 166:45-53, (2002). 

[138] E. Van Ranst, S.R. Utami, J. Shamshuddin. "Andisols on volcanic ash from Java Island, Indonesia : 

Physico-chemical properties and classification", Soil Science, 167:68-79, (2002). 

[139] E. Van Ranst, S.R. Utami, J. Vanderdeelen, J. Shamshuddin. "Surface reactivity of Andisols on volcanic 

ash along the Sunda arc crossing Java Island, Indonesia", Geoderma, 123:193-203, (2004). 

[140] K. Van Rompaey, E. Van Ranst, F. De Coninck, N. Vindevogel. "Dissolution characteristics of hectorite in 

inorganic acids". Applied Clay Science, 21 : 241-256, (2002). 

[141] K. Van Rompaey, E. Van Ranst, A. Verdoodt, F. De Coninck, 2006. Use of the test-mineral technique to 

distinguish simple acidolysis from acido-complexolysis in a Podzol profile. Geoderma (in press). 

257


IMPACT OF ACID DEPOSITION ON CATION LEACHING FROM 

MT. TALANG AIRFALL ASH 

Fiantis, D., Nelson 1 , E. Van Ranst 2 and J. Shamshuddin 3 

Department of Soil Science, Faculty of Agriculture University of Andala, Kampus Unand Limau Manis, Padang 

25163, Indonesia; 1 Department of Crop Estate, Polytechnic of Agriculture University of Andalas, Kampus Politani 

Tanjung Pati, 50 Kota, Sumbar, Indonesia; 2 Department of Geology and Soil Science, Laboratory of Soil Science, 

Ghent University, Krijgslaan 281/S1, B- 9000 Gent, Belgium; 3 Department of Land Management, Faculty of 

Agriculture, Universiti Putra Malaysia, Serdang 43400 Selangor, Malaysia 

Abstract 

An evaluation of the response of airfall ash from Mt. Talang on acid deposition and weathering 

rates was studied by using a controlled laboratory leaching experiment. Airfall ash from Mt. 

Talang was collected a few days after it was blown up by a phreatic eruption at the upper NE 

side of the volcano. The ash samples were leached with de-ionized water and nitric acid 0.05 M 

(pH 2) for seven weeks. Solutions leachates were collected after 2 and 48 hours, and after 7, 14, 

21, 28, 35 and 42 days for chemical analyses. Measured cations were Ca and Fe. Two sets of 

sample containers were constructed, namely (1) successive incubation and (2) separated 

incubation. The successive incubation set up consisted of the addition of new solutions to the 

containers after each collection of leachate to simulate the leaching conditions in the field. The 

containers for separate incubation were set up according to the respective time and discharge 

afterward. 

Acidic input increased iron leaching; Fe was increased by 1.75-folds in successive incubation 

and 47 times in separated incubation, while Ca was elevated 1.5 times in successive mode and 4folds 

in separate set. The Fe release was increased sharply after 3 weeks and started to level off 

after 6 weeks. Meanwhile, Ca was released sharply after 1 week and started to level off after 2 

weeks. In total, 0.08 to 0.13 % of iron was released after addition of de-ionized water in 

successive mode and 0.05 – 0.08% in separate mode. Treating the airfall ash with nitric acid 

yielded more Fe, in the range of 0.34 – 0.37% and 1.41 to 2.42 %, in successive and separate 

modes respectively. Addition of de-ionized water resulted in higher concentration of Ca in 

contrast to addition of nitric acid. The value of Ca between 2.54 to 6.64 % was obtained in the 

reconstructed field condition and between 6.04 – 6.84 % in separated sets. The total 

concentration of calcium after applying nitric acid was between 2.06 – 3.03 %, and 5.10 – 5.91 

%. 


Owing to its position in the mid-western part of the Barisan Mountain Range of Sumatra, to its 

shape and size and to its activity, Mt. Talang is one of the most important and active volcano in 

Sumatra. Mt. Talang is a strato volcano, formed of lava flows alternating with pyroclastic 

materials, emitted from various eruptive cases over the centuries. Summit elevation of Mt. 

Talang reaches 2896 m above sea level and located at 100° 40' 41.9304" E and 0° 58' 40.8072" S 

258


and the distance from the city of Padang to Talang is about 35 km. (Figure 1). Historical 

eruptions from Talang volcano have occurred many times from flank vents and most of the 

eruptions are moderate in size. On April 12 th , 2005 an explosion was heard 25 km from Talang 

and grayish ash was emitted to the sky. Ash fell to the south and eastern-northern slope of Mt. 

Talang. 

Volcanic ash, the smallest tephra fragments, is highly disruptive to economic activity 

because it covers just about everything, infiltrates most openings, and is highly abrasive. On the 

other hand, from these ashes of devastation arise some of the most productive soils in the world 

with the capacity to sustain high human population densities. 

Figure 1. Satellite image of Mt. Talang and surrounding area 

Airfall volcanic ash has fine particle size, vesicular nature with high surface area, high 

porosity and permeability enhance weathering rates [4]. Rapid weathering of the ash liberated 

cations through surface exchange with aqueous hydrogen ions [13]. Volcanic ash is believed to 

release elements faster than other primary or secondary crystalline minerals [11]. The primary 

proton donors in the weathering of airfall ash are both acidic aerosols, carbonic and organic acids 

[3]. Proton donors or acids affect weathering by providing H + which may attack rocks or 

minerals [12] The acidic aerosols, such as sulfuric acid (H2SO4), hydrochloric acid (HCl), 

fluoric acid (HF) and nitric acid (HNO3), which come from eruption plume during the eruption 

while the carbonic and organic acids derived from biota [3]. 

Both mineral and organic acids play an important role in soil environments and provided 

evidence that weathering of rocks and minerals are facilitated by these acids through 

259


organometallic complex formation or through metal chelation process [9]. Furthermore, [7] 

found out that the ratio between anion or cation released over protons-added from organic acids 

are greater than those from mineral acids. The ability of organic acids to complex metals is more 

important than the strength of mineral acids that have lower dissociation constant (pK1). Mineral 

acids are considered as strong noncomplex forming acids [12]. 

Solutions leached from the tephra layer indicate incongruent dissolution resulting in 

formation of a cation-depleted, silica-rich leached layer on glass and mineral surfaces [4] As 

reported by [1] the initial lechates from the 1980 eruption of Mt. St. Helens composed primarily 

of base cations (Ca 2+ > Na + >> Mg 2+ > K + ) and strong acid anions (SO4 2- >> Cl - > F - >> NO 3- ). 

The rate of aluminum release from colored volcanic glass in order of 10 -12 mol g -1 s -1 at pH 4.00. 

Colored volcanic glass release cations 1.5 times greater than non-colored glass, reflecting its 

lower stability [11]. As weathering progresses, dissolution rates are controlled by surface 

dissolution with concurrent diffusion of cations through the leached layer near the glass surface. 

A shift from incongruent to congruent dissolution presumably occurs when the increase in the 

diffusion length equals the rate of retreat of the solution-solid interface [14]. 

The primary objective of this study was to provide a direct measurement of acid 

dissolution from unweathered airfall ash deposits in a warm, humid climate regime. The 

questions addressed in this research concerning the initial stages of volcanic ash weathering 

including: (1) what are the initial cations releases from fresh volcanic ash; (2) does the volcanic 

ash dissolve stoichiometrically or incongruently? 

To answer these questions fresh airfall ash of Mt. Talang were subjected into laboratory 

dissolution experiment for 7 weeks with nitric acid, which is considered as strong mineral acid, 

de-ionized water as weak noncomplex acid and acetic acid of the organic acid. Lechates from ash 

deposits were collected weekly for chemical analysis and are used to calculate elemental fluxes 

and weathering rates of airfall ash. 

2.1. Study area 

2. MATERALS AND METHODS 

Mt. Talang is considered as type-A volcano and has been in continuous eruption for decades 

either from flank vent, radial fissures or summit of volcano. The area affected by volcanic 

activity covers at about 42103.6 ha and mostly from Quaternary age. The recent eruption of 

April 12, 2005, blew away airfall ash tephra over portions of Solok District of West Sumatra, 

Indonesia. The maximum thickness of ash was 5 cm in the upper NE slope of Mt. Talang and 

the minimum thickness of 1 mm blanketed the area in the foot slope. 

2.2. Collection and Analysis of Ash Lechates 

Airfall ash was collected from the affected areas of tea-plantation shortly after the April 12 th 

2005 eruption. The ash was collected prior to any rainfall and sealed in watertight containers 

until it was used for mineralogical and chemical analysis as well as applied it for the dissolution 

experiments. The airfall ash fractions were analyzed in grain mounts with a polarizing 

microscope. Elemental analyses of airfall ash were done by X-ray fluorescence spectrometry 

after ignition at 1100 0 C. 

260


The dissolution experiment was carried out as follows. One gram of airfall ash was 

placed in each 250 ml plastic container with a stopper, and 200 ml of de-ionized water and nitric 

acid 0.05 M (pH 2) for seven weeks at room temperature. Mixing of the solution was made by 

shaking the containers once a day for 60 minutes during the dissolution. The solution was 

separated after 1 hour, 24 hours, and after 2, 7, 14, 21, 28, 35 and 42 days. Chemical analysis of 

lechates were conducted to determine the pH, cations (Ca and Fe) were measured by AAS. 

Two sets of sample containers were constructed, namely (1) successive incubation and 

(2) separated incubation. The successive incubation set up consisted of the addition of new 

solutions to the containers after each collection of lechates to simulate the leaching conditions in 

the field. The containers for separate incubation was set up according to the respective time and 

discharge afterward. All values represent the mean of duplicate analyses. 

3. RESULTS AND DISCUSSION 

3.1. Mineralogical Characteristics of Mt. Talang Airfall Ash 

The mineralogical composition of the ash consisted of noncrystalline and crystalline 

components. The noncrystalline mineral is volcanic glass (30%) and the rest are crystalline 

minerals. The glassy materials of volcanic glass appear optically isotropic under crossed 

polarizer microscope and usually present as clusters of small particles with vesicular 

morphology. Volcanic glass, as it was believed [2], is the most weatherable components as a 

result of its amorphous nature in volcanic deposits. Weathering of volcanic glass can be 

described in term of a combination of parabolic and linear kinetics, reflecting the hydration of 

glass and the formation of secondary clay minerals. Furthermore they stated that the 

mineralogical composition of volcanic ash varies widely as a function of particle-size and that 

volcanic glass increases in relative proportion to plagioclase as the particle size decreases. 

The crystalline minerals include andesine (1%), quartz ( 32 mm). As it is, the 

mineralogical composition of volcanic ash varies according to rock types. Ash of rhyolite, dacite 

or andesite composition is dominated by noncolored volcanic glass with lesser amounts of 

plagioclase, pyroxenes, and ferromagnesian minerals. On the other hand, volcanic ash having the 

composition of basalt and basaltic andesite composition is dominated by colored volcanic glass 

accompanied by plagioclase, olivine, pyroxenes and ferromagnesian minerals [2]. 

261


3.2. Elemental Composition of Mt. Talang Airfall Ash 

Air fall ash, as a parent material of soils, controls soil formation more than any other parent 

materials. The behavior of chemical elements in airfall ash can be inferred by comparing the 

total elemental analysis. The elemental composition of the airfall ash is depicted in Tables 1. 

Each element is expressed in oxide percentage on the basis of an oven-dried weight (105 0 C). 

Based on the silica content of 54%, the airfall ash of Mt. Talang can be considered as basalticandesitic 

type. A classification of volcanic ash was proposed by [10] into five groups based on 

the silica (SiO2) content: rhyolite (100-70%); dacite (70-62%); andesite (62-58%); basaltic 

andesitic (58-53.5%) and basalt (53.5-45%). The result of this study is different with the report 

of [5] that volcanic ash of Mt. Marapi, located 140 km north of Mt. Talang, are considered as 

andesitic type since the silica contents was higher 15%. Japanese soil scientists stated that silica 

content of volcanic ash from Japan in the range of 48 – 73% and exists strong correlation 

between silica content and most of chemical elements except for K [15]. Similar findings were 

also reported for volcanic ash originating from New Zealand [8]. SiO2 is regarded as one of the 

immobile element found in tephra as well as Al2O3 and Fe2O3 [2]. 

Element 

Composition (%) 

Fresh Oxalate-treated 

SiO2 54.37 64.36 

Al2O3 18.33 15.00 

Fe2O3 4.82 5.95 

CaO 4.19 4.25 

MgO 1.33 1.42 

K2O 1.15 1.49 

Na2O 0.61 0.67 

LOI 4.2 4.88 

Table 1: Contents of major elements in fresh and oxalate-treated 

airfall ash of Mt. Talang 

The molar ratio between SiO2/Al2O3 is 6.14 in fresh volcanic ash and decrease into 4.29 

in oxalate-treated ash of Mt. Talang. The down shift value of the molar ratio is assumed to be 

largely due to presence of the amorphous and noncrystalline components of volcanic materials. 

This is in accordance with the report else where in Japan [15]. Meanwhile the SiO2, Al2O3 and 

Fe2O3 are originated from both volcanic glass and plagioclase while Fe2O3 can be found also in 

mafic minerals [10]. 

The alkaline earth elements (CaO and MgO) found in the studied ash are higher then the 

alkaline elements (K2O and Na2O). The higher contents of CaO and MgO because the samples 

are very new and is not subjected to any weathering process yet. These data are in line with 

those obtained by [10] that CaO and Na2O are originated from volcanic glass and plagioclase, 

MgO is from mafic mineral and K2O mainly occurs in volcanic glass. They added that 

proportion of CaO, Na2O and MgO were decreased as weatherings proceed contrary to K2O 

content. Both CaO and Na2O have high solubility and easily lost by leaching. The mobility 

sequence found in volcanic ash parent materials are in order: CaO, Na2O >SiO2 >MgO > Al2O3, 

Fe2O3, K2O [7, 10, 2]. 

262


Removal of the amorphous constituents by using oxalate increased the concentration of 

all elements except for the aluminum oxide concentration, which is down from 18% to 15%. 

Although SiO2 concentration is exceeding the requirement for basaltic andesitic, it is our belief 

that treated the samples with chemical solutions does not necessary change the rock type of the 

airfall ash from basaltic andesitic into dacitic. The ammonium oxalate acid dissolution is 

intended to remove the amorphous fraction that is coating some of the crystalline particles. 

Unfortunately, we do not have any value of dissolved cations from the lechates to be reported 

and compared with the concentration of cations from ash-residue or solid components after 

ignition to 1100 0 C. 

3.3. Dissolution Rate of Calcium 

The solubility of solid-phase of calcium upon leaching with different acids in successive and 

separate mode incubation is shown in Table 2 and 3. Different results obtained from the two 

mode of incubation. Ca obtained from the successive mode, reflecting the leaching conditions in 

the field, are lower than the separated incubation mode. Comparable results were also reported 

by [3] maximum solute concentrations in solutions draining from tephra layer during rainy 

season during initial weathering study (12 months) and there was a distinct decrease in the 

annual concentrations of several solutes such as calcium, sodium, silicon and bicarbonate after 4 

years of study. 

Location 

Bukit Sileh 

1.300 m a.s.l 

Aie Batumbuk 

1.100 m a.s.l 

Ca concentration in the lechates (g/kg) 

Treatments 

After 2 h After 24 hAfter 1 w After 2 w After 3 w After 4 w After 5 w After 6 w 

H2O 13.83 18.82 102.47 57.40 13.18 31.89 15.56 0.39 

Acetic acid 19.72 20.48 229.17 85.46 28.49 25.09 39.86 0.52 

HNO2 17.38 13.35 161.99 30.19 4.68 15.73 16.25 0.27 

NH4 OACe 14.02 14.78 339.71 161.14 60.80 23.38 65.56 0.61 

H2O 18.05 20.08 451.96 92.26 31.04 31.04 19.72 0.34 

Acetic acid 20.41 19.02 503.83 296.34 45.49 18.28 32.22 1.06 

HNO2 20.27 19.02 192.60 46.34 6.38 2.98 14.86 0.31 

NH4 OACe 19.04 21.01 416.24 304.00 86.31 26.79 32.92 0.76 

Table 2: Ca concentration in the lechates as a function of residence time and type of acids in successive 

mode of incubation 

263


Location 

Ca concentration in the lechates (g/kg) 

Treatments 

After 2 h After 24 hAfter 1 w After 2 w After 3 w After 4 w After 5 w After 6 w 

Bukit Sileh 

H2O Acetic acid 

13.83 

19.72 

18.82 

20.48 

158.59 

130.53 

117.77 

122.02 

105.02 

99.06 

96.51 

109.27 

90.56 

88.47 

3.24 

2.36 

1.300 m a.s.l 

HNO2 NH4 OACe 

17.38 

14.02 

13.35 

14.78 

117.77 

140.73 

94.81 

123.72 

105.87 

67.60 

81.21 

102.47 

78.06 

105.83 

2.02 

3.60 

Aie Batumbuk 

1.100 m a.s.l 

H 2O 18.05 20.08 144.13 141.58 109.27 138.18 109.31 2.92 

Acetic acid 20.41 19.02 157.74 134.78 126.28 123.72 107.22 2.77 

HNO 2 20.27 19.02 120.32 108.42 107.57 111.82 100.97 2.53 

NH 4 OACe 19.04 21.01 149.23 139.88 80.36 168.79 138.47 4.48 

Table 3: Ca concentration in the lechates as a function of residence time and type of acids in separate 


Comparing the source of proton donors used to age the airfall ash of Mt. Talang, acetic 

acid released cations more than deionized water, nitric acid and sulfuric acid as well as 

ammonium acetate. Acetic acid is one of the organic acids, nitric acid is considered as strong 

mineral acid, deionized water is a weak acid while ammonium acetate is an alkaline solution 

with pH value of 7. Organic acids, as explained by [12], are capable of dissolving and 

complexing the cations from the surface layer of colloid or clay particles. Deionized water as a 

weak acid, is a source of protons in soil. It can be involved in hydrolytic reactions leading to 

partial dissolution (incongruent) and total dissolution (congruent) of minerals as time progresses. 

Furthermore, they discussed that strong acid, like nitric acid with a pKa of -1, capable of 

lowering the pH and to dissolve cations congruently, leaving no residue in the mineral surfaces. 

Changes in leachates chemistry of progressive weathered of ash during incubation are 

illustrated in Figure 2 and Figure 3. As indicated, the amount of Ca in leachates increases with 

time, especially after 24 hours of contact time between the ash and the proton donor of each 

respective solution and started to level off after 5 weeks. Similar trend was also observed by 

[14] both in field and laboratory experiments of the Mt. St. Helens ash fall. They explained that 

increasing of the cations (ca and Mg) from field study reflecting retention of the cations in the 

soils after 2 years. Meanwhile higher amount of cations in lechates obtained from the leaching 

experiments as surface layer of the ash become cations-depleted. The same author presumed that 

rapid weathering of the ash liberated cations through surface exchange with aqueous hydrogen 

ions. 

264


Ca dissolution (%) 

8.000 

7.000 

6.000 

5.000 

4.000 

3.000 

2.000 

1.000 

0.000 

Bukit Sileh (Successive incubation mode) 

After 2 h After 24 h After 1 w After 2 w After 3 w After 4 w After 5 w 

265 

Times 

H2O H Acetat HNO2 NH4 OACe 

Figure 2: Concentration of Ca after leached with different acids for 5 weeks 

Ca Dissolution (%) 

7.000 

6.000 

5.000 

4.000 

3.000 

2.000 

1.000 

0.000 

Bukit Sileh (separate incubation mode) 


Times 


Figure 3: Concentration of Ca after leached with different acids for 5 weeks 

3.4. Dissolution Rate of Iron 

The solubility of solid-phase of iron upon leaching with different acids in successive 

mode incubation is shown in Table 4 and Figure 4, whereas the result of the separated mode 

incubation is displayed in Table 5 and Figure 5. Fe concentrations are much lower compared to 

concentration of Ca. Aqueous concentration of iron is low because of the low solubility of the 

iron during initial period of weathering. As explained by [3] that Fe display low solubility 

during the first two years of experiments and increase slightly during the last two stages of their 

study. The dissolution of iron by soluble organic acids involving complexation process for quite 

long period of time [12].


Location Treatments 

After 2 h After 24 h 

Fe concentration in the lechates (g/kg) 

After 1 w After 2 w After 3 w After 4 w After 5 w After 6 w 

Bukit Sileh 

H2O Acetic acid 

0.45 

1.91 

0.97 

2.08 

0.01 

1.66 

2.00 

3.57 

8.27 

2.29 

0.43 

1.74 

0.24 

2.18 

0.15 

1.30 

1.300 m a.s.l 

HNO2 NH4 OACe 

5.35 

0.05 

6.25 

0.06 

2.46 

0.26 

6.27 

0.42 

3.56 

0.50 

4.15 

0.43 

4.48 

0.52 

1.89 

0.39 

Aie Batumbuk 

1.100 m a.s.l 

H2O 0.09 0.13 0.01 2.22 4.44 0.14 0.94 0.37 

Acetic acid 1.93 1.49 1.41 4.54 2.36 2.20 2.33 1.38 

HNO2 5.10 6.13 1.66 6.76 4.24 5.72 5.12 2.75 

NH4 OACe 0.00 0.05 0.30 0.45 0.16 0.40 1.15 0.37 

Table 4: Fe concentration in the lechates as a function of residence time and type of acids in successive 


Location 

Bukit Sileh 

1.300 m a.s.l 

Aie Batumbuk 

1.100 m a.s.l 

Treatments 

After 2 h After 24 h 

Fe concentration in the lechates (g/kg) 

After 1 w After 2 w After 3 w After 4 w After 5 w After 6 w 

H2O 0.45 0.97 0.72 0.72 0.72 0.72 0.72 0.00 

Acetic acid 1.91 2.08 0.72 0.72 7.93 10.09 10.81 0.29 

HNO2 5.35 6.25 58.36 7.20 48.27 54.76 61.96 0.29 

NH4 OACe 0.05 0.06 2.88 4.32 4.32 3.60 8.65 0.24 

H2O 0.09 0.13 0.72 2.88 2.16 0.72 0.72 0.11 

Acetic acid 1.93 1.49 2.88 6.48 6.48 4.32 7.93 0.26 

HNO2 5.10 6.13 3.60 17.29 36.02 36.02 36.74 0.17 

NH4 OACe 0.00 0.05 0.72 4.32 0.72 0.72 5.76 0.09 

Table 5: Ca concentration in the lechates as a function of residence time and type of acids in separate 


Fe dissolution (%) 

0.400 

0.350 

0.300 

0.250 

0.200 

0.150 

0.100 

0.050 

0.000 

Aie Batumbuk (successive incubation mode) 


266 

Times 


Figure 4: Concentration of Fe after leached with different acids for 5 weeks


Fe dissolution (%) 

0.800 

0.600 

0.400 

0.200 

0.000 

Aie Batumbuk (Separate incubation mode) 

After 2 h After 24 

h 

After 1 w After 2 w After 3 w After 4 w After 5 w 

267 

Times 


Figure 4: Concentration of Fe after leached with different acids for 5 weeks 

4. CONCLUSIONS 

The preceding data and discussion indicate that the recent airfall ash of Mt. Talang considered as 

basaltic andesitic rock type with higher amount of volcanic glass and plagioclase. Other primary 

minerals exists are hypersthene, augite, hornblende, opaque or ferromagnesian minerals. The 

elemental composition of the ash reaches the value of 55% for silica, with lesser amount of 

calcium, magnesium, potassium and sodium oxides. The calcium concentration detected in the 

leachates increased sharply up to 4 weeks and started to level off after 5 weeks. Among the 

proton donors, acetic acid is capable to dissolve more cations from air fall ash compared to other 

source proton donors such as deionized water, nitric acid and ammonium acetate. Concentration 

of Ca is higher thru the experimental study compared to Fe concentration. 


This work is supported by Directorate of Higher Education Department of National Education of 

Republic of Indonesia under Fundamental Research Grant no: 005/SP3/PP/DP2M/II/2006, 

granted to the first author. Total elemental analyses with XRF Spectrophotometer were 

performed at the Laboratory of Research and Development of PT. Semen Padang, Indonesia. 

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New Zealand case study. In: S. M. Colman and D. P. Dethier (eds.), Rates of Chemical Weathering of Rocks and 

Minerals. Academic Press, Inc. Orlando. 265-330 pp. (1986). 

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Interactions of Soil Minerals with Natural Organics and Microbes. P. M. Huang and M. Schnitzer (eds). Soil Sci. 

Soc. Am. Spec. Publ. 17. Madison, WI, pp.453-495. (1986). 

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influencing the mobilities of major chemical elements. Soil Sci. 132:331-346. (1981). 

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Elsevier, Amsterdam, the Netherlands. 288 p. (1993). 

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Studies. Soil Sci. Vol. 151, No. 1:61-75. (1991). 

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Acta. 47, 805-815. (1983). 

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(1975). 

268


STONE LINES AND WEATHERING PROFILES OF FERRALLITIC 

SOILS IN NORTHEASTERN ARGENTINA 

Morrás, H. 1* , Moretti, L. 1 , Píccolo, G. 2 , Zech,W. 3 

1INTA-CIRN, Instituto de Suelos, 1712 Castelar, Buenos Aires, Argentina, 2 INTA-EEA Cerro Azul, 3313 Cerro 

Azul, Misiones, Argentina, 3 Institute of Soil Science, University of Bayreuth, Bayreuth, Germany 

Abstract 

A ferrallitic pedological mantle with Ultisols and a lower proportion of Oxisols, is found in the Province of 

Misiones, in northeastern Argentina. This ferrallitic material usually has a depth of 3 to 7 m above the weathered 

basalt, and frequently a “stone line”, many times lying on a thin structured layer, appears in its lower part, close to 

the limit with the saprolite. 

The autochthonous or allochthonous origin of materials composing this type of profile, frequent in tropical and 

subtropical environments, is controversially discussed in the literature. Referring specifically to the area of Misiones 

and to neighbouring regions in Brazil and Paraguay, Iriondo and Kröhling [5] postulated that the material that covers 

the basaltic rock and in which the red soils have developed is an eolian sediment (a “tropical loess”) of upper 

Pleistocene age, deflated from the alluvial plains of the Paraná and Uruguay rivers. 

The work we have carried out in this region, allows us to distinguish two basic types of “stone lines”: the first one is 

a “nodular line”, more typical for the southern part of Misiones, composed by goethitic nodules of gravel size, and 

appearing to derive from differential weathering of more resistant basaltic layers. The second one is a “siliceous” 

layer of quarzitic nature, characterizing profiles in central Misiones: these silica concentrations in some instances are 

in situ relicts of former quartz veins in the basalt, and in other cases the “line” may be defined as a “silcrete”; a 

secondary accumulation of quartz on relictic quartz veins seems to happen in other cases. Concerning the blocky 

structured subsurface levels below the “stone lines”, the results lead to conclude that they are not paleosols, and that 

they can not be considered as an evidence of paleosurfaces. 

Consequently, according to our field observations and to our laboratory results (clay and sand mineralogy, magnetic 

susceptibility, geochemical data, granulometry, micromorphology and stable carbon isotope analysis), we consider 

that the “stone lines” as well as the surface ferrallitic soil materials in Misiones have an autochthonous origin, 

deriving from in situ weathering of basaltic rock. 

INTRODUCTION 

A ferrallitic pedological mantle with Ultisols and a lower proportion of Oxisols, covers most part 

of the landscape in the Province of Misiones, in northeastern Argentina. This ferrallitic material 

usually has a depth of 3 to 7 m above the weathered basalt, and frequently a “stone line’, many 

times lying on a thin structured layer, appears in its lower part, close to the limit with the 

saprolite. 

The nomenclature of different layers and the autochthonous or allochthonous origin of 

materials composing this type of complex profile, frequent in tropical and subtropical 

environments, is a controversial matter that has deserved numerous interpretations and proposals 

[19, 20]. The presence of the “stone lines” suggests the existence of an unconformity and this 

feature has been generally considered to be of sedimentological rather than of pedological origin. 

Thus, most part of diverse hypotheses proposed considers processes of generation, movement 

and accumulation of pebbles, though differing in the interpretation of their genesis and that of the 

overlying material. 

269


According to Segalen [19] the different interpretations currently admitted concerning the 

origin of the “stone lines” can be grouped in the following way: 1) processes of pediplanation 

related to climatic changes, producing the erosion of laterites and quartz veins followed by the 

transport of their fragments; 2) colluvial processes in steep slopes, producing the erosion and 

transport of hardened horizons and veins; 3) autochthony or in situ sinking of hardened laterites 

previously fragmented by chemical weathering. The activity of the soil fauna has also been 

proposed to be responsible for the downward movement of the pebbles within the profiles, and 

for covering them with fine textured materials. 

For the origin of surface material above the stone lines different interpretations have also 

been suggested. A two stages process made up by a first one of deflation and exposure of pebbles 

and a second one of covering due to a later sedimentation is among the older explanations; this 

would be eventually possible at certain localities but it is considered unacceptable as a general 

interpretation [3, 19, 20]. At present, two explanations of general application about the origin of 

the fine textured surface materials are a colluvial deposition and an upward vertical transport of 

fine material by termites from the saprolite [19, 20]. Segalen [19] also mentions that several 

authors have presented interpretations involving the simultaneous effect of different processes in 

the development of these soil profiles. Recently, Johnson [7, 8] proposed a general explanation 

combining different theories and principles of geomorphology, pedology and hydrology that he 

named “the dynamic denudation theory”, and in which the dynamic processes and conditions are 

driven by gravity, water and biotic agents. 

With regard to Misiones in Argentina, the red soils were traditionally considered to be the 

result of in situ weathering of the tholeiitic basalt of the Serra Geral Formation [18]. On the 

contrary, Iriondo and Kröhling [5] referring to Misiones as well as to neighbouring regions in 

Brazil and Paraguay, postulated that the material covering the basaltic rock and in which the red 

soils have developed is an eolian sediment of upper Pleistocene age, deflated from the alluvial 

plains of the Paraná and the Uruguay rivers. The authors consider this surface material to be a 

“tropical loess” and have formally named it “Oberá Formation”, identifying an “Upper member” 

and a “Lower member” separated by the “stone line”. Besides some analytical data, the main 

arguments are the presence of a “stone line” described as platy-gravel sized silica and, less 

frequently, the presence of a buried soil (classified as Ultisol) represented by a moderately 

structured B horizon below the ¨stone line¨ and therefore regarded as an evidence of a 

paleosurface. 

Similarly, Lichte y Behling [10] referring to the Quaternary landscape evolution in 

southeastern Brazil, also consider that the “stone lines” have developed on a now fossil surface 

that was subsequently covered by an eolian sediment. For these authors the quartz pebbles derive 

from quartz veins included in the Precambrian crystalline rocks, which were distributed by heavy 

rains along the slopes, and later on covered by fine eolian sediments deriving at least partly from 

the lateritic cover of the Sudamericana plain. 

Consequently, taking into account the diversity of hypotheses concerning the origin of this 

type of ferrallitic soils with “stone lines”, and due to the role they play with respect to the 

interpretation of landscape evolution, we focus since some years on this phenomena in Misiones 

[13, 14, 15, 16]. In the following our results will be summarized. 

270


MATERIAL AND METHODS 

The Province of Misiones is located in northeastern Argentina, around 28º S and 54º W (Fig. 1). 

The climate is subtropical humid without dry season; the mean annual temperature is around 

20°C and the mean annual rainfall increases from 1750 mm in the south to 1950 mm in the north. 

The present vegetation is a subtropical forest, except a narrow strip along the southern border 

with a savanna type vegetation. 

The field work for the study of ferrallitic soils was for the most part done on exposed 

profiles along the main roads in the Province. The sites observed and described up to the present 

are more than sixty, and several of the profiles in different sectors of the Province have been 

selected and sampled for detailed studies. Some soil profiles in concave topographic positions 

have also been sampled and analyzed. The samples were characterized by conventional analysis; 

in addition clay mineralogy (DRX and TEM), sand mineralogy (optical microscopy and SEM), 

magnetic mineralogy (magnetic susceptibility), micromorphology, geochemistry (macro- and 

micro-elements), and stable carbon isotopes analysis were taken into consideration. 

Figure 1: Map of the Misiones Province, and location of some of the surveyed sites. 

RESULTS 

Considering that the genesis of ¨stone lines¨ and associated ¨structured horizons¨ is unclear, we 

have focused our study on these features. The work we have carried out in this region, allowed 

us to distinguish several morphological types of ¨stone lines¨, from which two basic 

compositional types were identified. 

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a) The ¨nodular lines¨ 

The first type of “stone line” we named “nodular line” (Fig. 5-A), typical for the southern part 

but also observed in other sectors of Misiones, is composed by ferruginous nodules of gravel 

size, usually with a mean size of around 15 mm. According to their mineralogy and morphology 

three groups were distinguished: the first one consists of hematitic nodules, dark red in colour 

and bright, and being the smallest in size; the second group is composed by goethitic nodules, 

reddish yellow in colour, opaque, and the bigger in size; the third group is composed by nodules 

of intermediate aspect and composition. The hematitic nodules occur in low proportion along the 

profile, as well above as below of the ¨stone line¨ with a slight maximum at that level; the 

goethitic nodules are in a high proportion within the ¨stone line¨ and appear only in this layer, 

while the intermediate nodules are in low proportion above and below the ¨stone line¨ showing 

there a sharp quantitative increment though the increases in size is progressive (Fig. 2). 

Though the nodules are more abundant at a particular level thus defining a ¨stone line¨, the 

fact that those ïron gravels¨ are not restricted to that level, together with their verticals variation 

in quantity, size and composition, suggest that they are not the result of a sedimentary process of 

accumulation. Secondly, the goethitic nature of gravels appearing exclusively at the “stone line” 

level, would not be compatible with their residence at a surface under an arid climate. 

Moreover, transitional vertical or horizontal steps of rock weathering observed in several 

profiles have furnished the evidence of the in situ formation of this type of “stone line”: thus for 

example, it was observed the transition from homogeneous saprolite bodies to levels with an 

incipient individualisation of soft rounded and more yellowish nodules, in turn passing to 

rounded hardened fragments increasingly individualised and sparsed, giving finally rise to a kind 

of relictic ¨stone line¨ (Figs. 5-C, 5-E, 5-F). Microscopic analysis of the nodules forming the 

“stone line” shows an internal porphyric texture with weathered phenocrysts, partially filled with 

goethitic iron, thus revealing its relationship with the basaltic rock. 

b) The ¨siliceous lines¨ 

The second type of ¨stone line¨, mainly observed in the central part of the Province, is a 

“siliceous” level of quartzitic nature (Fig. 5-B). In this type of ¨line¨ the silica appears as 

horizontal levels of variable thickness, from a few millimeters (in this case usually fractured and 

with the appearance of laminar fragments) up to 30 cm or more. 

In some instances these silica concentrations are clearly in situ relicts of former quartz 

veins in the basalt. Lateral as well as vertical transitions from weathered basalt levels including 

quartz veins to pedogenized red materials including quartz ¨lines¨ have been observed (Figs. 5-E, 

5-F). In some cases these siliceous levels into the pedogenized material seem to result from a 

secondary crystallisation of quartz, thus developing as ¨silcretes¨. Besides, in several instances, a 

secondary crystallisation of quartz seems to happen on relictic quartz veins; the upper face of 

these levels shows an irregular morphology that could be the result of dissolution as well as 

crystallization of silica. 

In every case it is clear that the siliceous levels are basically massive and continuous, i.e. 

they are not constituted by pebbles or fragments that were submitted to transport. Some 

fragmentation of thick siliceous ¨lines¨ observed in some cases on vertical walls is the artificial 

result of the excavation, which is not observed when the ¨levels¨ are carefully exposed removing 

272


the covering material. Thin veins may be naturally fragmented, but the fragments appear 

perfectly accommodated as the pieces of a floor (Fig. 5-D), this being the result of internal 

movements and eventually from processes of dissolution, during the processes of rock 

weathering and soil formation. 

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In these profiles, the ferruginous nodules are scarce and its vertical distribution is different to 

the profiles with ¨nodular lines¨. In some cases levels showing a relatively higher 

concentration of iron nodules, dark red and hematitic, and appearing regularly with depth, 

coincides with a higher concentration of quartz gravels (Fig. 3). The last may be interpreted as 

fragments of presently dissolved thin relictic quartz veins; it may be hypothesized that those 

former veins have slowing down the process of lixiviation thus contributing to an 

accumulation of iron and promoting the development of iron nodules. 

c) The ¨structured horizons¨ 

Concerning the blocky structured subsurface levels below the “stone lines” (Figs. 5-A, 5-F), 

field and analytical results lead to the conclusion that they are not buried paleosols and that 

they can not be considered as an evidence of paleosurfaces. Two processes may be 

responsible for the formation of these structured layers: 1) The first one is similar to the 

“stone line” development described above, to which sometimes they are associated: in this 

case a lateral sequence of weathering, from the weathered rock to a structured and fine 

textured material, can be observed (Figs. 5-E, 5-F). 2) In a second one, nodular or siliceous 

layers derived from the above mentioned processes, may exert a “protection” effect on the 

underlying fine textured materials against the weathering front, thus allowing the 

development or conservation of structural blocky units. As a consequence, places are found in 

which a well defined “stone line” covers a continuous structured horizon, as well as places 

where short discontinuous ¨lines¨ or even isolated gravels preserve structured micro-horizons, 

surrounded by a differently organized material. 

Besides the profiles showing one of the above mentioned two types of ¨stone lines¨, 

other situations have been also observed: profiles with several superimposed ¨lines¨ of the 

same type; profiles with different types of ¨lines¨ superimposed at different depths; ¨lines¨ 

with dark and bright gravels of laminar morphology; profiles without ¨lines¨; ¨stone lines¨ 

appearing above, below as well as inside of structured layers, thus do not having a fixed 

positional relation with structured horizons, and “lines” lying directly on or within the 

saprolite. It is also to be mentioned that besides the horizontal facies, many times “stone 

lines” and structured layers show sub-horizontal directions and bifurcations or branchings 

(Fig. 5-A). ¨Lines¨ with an undulated morphology, sometimes described as ¨funnel-like¨ [20], 

are also common. 

d) Clay mineralogy. 

The XR-diffractometry of the clay fraction from different profiles, those having a nodular 

“stone line” as well as those with a siliceous line, shows a similar composition and gradual 

mineralogical variation from the saprolite up to the soil surface (Fig. 4). The more abundant 

components of the fraction are kaolinitic minerals, i.e mainly kaolinite and some halloysite, 

the last evidenced clearly by TEM; the content of these phyllosilicates decrease progressively 

from the saprolite up to the surface. At the same time, a continuous increase of chloritic 

minerals is observed from the “stone lines” up to the surface, where they comprise around the 

15% of the clay fraction. These last minerals known under different names, v.g. pseudochlorites, 

aluminous chlorite, aluminous vermiculites, develop in pedogenic environments. 

This mineralogical vertical variation suggests that these profiles are the result of in situ 

weathering of the basalt rock. Besides, it can be observed that the mineralogical composition 

of structured levels below the “stone lines”, which have been interpreted as paleosols, have a 

mineralogical composition similar to that of the saprolite and thus differing from that of the 

upper B soil horizons. 

274


e) Sand mineralogy and quartz exoscopy 

The sand fraction of the ferrallitic soils in Misiones is almost exclusively composed by quartz 

and magnetite, the first being more abundant in the finer fractions while the second is more 

abundant in the coarser ones. Variable proportions of pseudosand grains and small iron 

nodules are also observed by microscopy. Other stable minerals as ilmenite, anatase and rutile 

have been detected by XRD [2, 12]. The mineralogical composition of sands is thus typical 

for highly weathered materials. 

On the other hand, the morphological study of quartz grains by optical microscopy and 

by SEM, recording their general morphology and the features on their surfaces, provides 

information about their history, i.e. processes of transport and chemical environment that have 

affected the materials where the grains are included [4, 9]. 

Microscopic analysis of the sand fraction from soils of Misiones reveals that a 

considerable part of quartz grains have experienced a high degree of weathering, characterised 

by deep and interconnected pits of dissolution (Fig. 5-G). On the other hand, many of the 

grains are clearly the result of secondary crystallisation of quartz. This secondary quartz can 

be observed as individualized single grains, or as a secondary crystallisation on the surface of 

other quartz grains acting as a nucleus or template for silica deposition (Fig. 5-G). Some of 

the grains appear rounded under optical microscopy, but under the SEM these grains show 

sharp and well developed crystal faces (Fig. 5-H). Besides, these grains show on their surface 

typical marks of dissolution with an inverted trigonal symmetry [12] 

The exoscopy performed on sand grains from different horizons of ferrallitic soils from 

Misiones, do not show evidences of eolian transport. On the contrary clear traces of quartz 

crystallisation and of chemical dissolution appear. Very interesting are those grains showing 

both processes, a first one of quartz crystallisation, with silica supposedly mainly coming 

from more weatherable minerals, followed by the dissolution of that secondary quartz (Fig. 5- 

275


H). Thus, morphology and surface textures of quartz grains are consistent with a in situ 

development of these ferrallitic soils. 

f) Magnetic susceptibility 

Magnetic susceptibility was measured in the field and in the laboratory, in this case at high 

and low frequency. Results obtained show high values, fitting the concept of “magnetic” soils, 

increasing progressively from the saprolite up to the soil surface. The difference between high 

and low MS –the frequency dependent MS– is low in the saprolite, shows a rapid increase 

from the “stone line” to lower B horizons, and then keeps similar differences up to the surface 

(Figs. 2, 3). 

The gradual increase of MS from the saprolite towards the surface can be related to a 

gradual increment in the magnetite content, a highly resistant mineral found in the basalt rock 

[2]. In turn, the high value of the frequency dependent MS above the “stone line”, is an 

indication of the existence of superparamagnetic magnetite, which is of pedogenic origin. 

Thus, both results suggest that these soil profiles are developed through in situ ferrallitic 

processes of weathering from the basalt. Besides, data from the structured horizons below the 

stone line differ from the soil horizons above it, thus being an additional indication that they 

are not paleosols. 

g) Granulometry 

The granulometric data show a gradual increase of clay and silt fractions from the surface to 

the middle part of the B horizons, and then a progressive decrease towards the base of the 

saprolite (Figs. 2, 3). The maximum of fine materials observed in the B horizon would be the 

result of a twofold process, in a one hand the result of the process of illuviation typical for 

Ultisols, and in the other hand a process of argilogenesis due to rock weathering and soil 

development. Particularly, the progressive increase of fine fractions from the saprolite 

towards the middle part of B horizons suggests that the materials are in situ. Besides, the 

content of fine fractions in the structured horizons below the “stone lines” are quite different 

from the B horizons, and do not seem to correspond to a paleo Ultisol as has been proposed. 

h) Geochemistry 

Total amounts of selected chemical elements and their ratios generally show continuous 

transitions from the saprolite up to the soil surface, evidencing the weathering process and the 

neoformation of minerals that have occurred in these soils. Total content of silica increases 

rapidly above the saprolite, due to the neoformation of clay minerals as well as quartz 

crystallisation. The Si/Al ratio increases progressively towards the surface, running parallel 

with the increase of chloritic minerals in the same direction (Fig. 3). A stable element as Zr 

increases progressively towards the surface, which would reflect the increasing intensity of 

weathering in the same direction. Weathering indices such as the one of Parker and 

homogeneity indices such as Ti/Zr do not show discordances (Fig. 3). But the same elements 

and certain ratios shift significantly below the “stone lines”. These results indicate that the 

reddish materials and the “structured horizons” below the “stone lines” do not correspond to a 

paleosol and to a lower member of a sedimentary formation as has been interpreted [5], but to 

slightly pedogenized transitional levels between the saprolite and the B horizons of the soils. 

276


i) Stable Carbon Isotopes 

The stable carbon isotope composition of plants differs according to their photosynthetic 

pathway (C3, C4, and CAM). δ 13 C values of C3 plants like trees and almost all the plants in 

temperate and cold regions, range from approximately –32‰ to –20‰ PDB, with a mean of – 

27‰. In contrast δ 13 C values of C4 plants, adapted to conditions of higher hydric stress, range 

from –17‰ to –9‰, with a mean of –13‰ [11, 17]. Isotopic fractionation depends not only 

on the type of vegetation but also on the plant environment, the CO2 atmospheric 

concentration, the temperature and on the humidity level. During litter decomposition and 

humification the isotopic signal of plants is transferred into the soil organic matter (SOM). 

Thus, the analysis of carbon isotopic composition of SOM may allow to deduce information 

about the environments and climatic conditions under which plants have grown in former 

times. 

Results obtained in Misiones [16] show that surface soil horizons (0-50 cm) have δ 13 C 

values around –25‰ in accordance with the present humid climate and a C3 vegetation cover. 

At around one meter depth the isotopic signature shows a significant enrichment in δ 13 C of up 

to –15‰ (Figs. 2, 3).This result indicates that the SOM has derived from a vegetation 

dominated by C4 plants developed under conditions of hydric stress in a savanna 

environment. Such conditions have probably existed in Misiones during the Last Glacial 

Maximum and the first half of the Holocene, as it is reported by several authors in southern 

Brazil [6, 17]. 

In the lower part of the profiles, the measurement of δ 13 C gives intermediate values 

(around -21‰) that are more difficult to be explained. Anyway, and in accordance with the 

interpretations made for similar situations, it is considered that these δ 13 C values result from a 

vegetation dominated by C3 plants in an open forest and under intermediate climatic 

conditions. Consequently, in the vicinity of the “stone lines” there are no evidences of arid to 

semiarid environmental conditions suitable for a denudation, accumulation of gravels on a 

paleosurface, and a later eolian sedimentation several meters thick during the LGM as has 

been proposed by Iriondo and Kröhling [5]. 

DISCUSSION AND CONCLUSIONS 

According to our field and laboratory results, it is possible to attribute an autochthonous 

origin to the “stone lines” appearing in the red soils of Misiones. 

In the case of the “nodular lines”, the rounded goethitic gravels seem to derive from a 

differential weathering of relatively more resistant basaltic layers. Transitional situations 

between the weathered basalt and the well defined “stone lines” clearly show the origin and 

the process of individualisation and accumulation of single nodules. Besides, the ferruginous 

nodules are not restricted to the “stone lines”. The hematitic ones as well as those with a 

partial covering of hematite at their surfaces, both appearing in an increasing proportion with 

depth down to the “stone line”, may also be interpreted as relictic fragments of the basaltic 

saprolite, i.e. formed similarly to the ones in the “stone line” but that has been progressively 

weathered, sparsed and covered by hematite as the result of soil development. 

In the case of the “siliceous lines” several evidences indicate that they are also 

autochthonous, and derived from pre-existing quartz veins within the basalt. Here also 

transitional situations between the weathered basalt intruded by quartz veins, and silica 

accumulations into pedogenized materials have been observed. Besides it has clearly appeared 

that platy siliceous gravels are not transported and that they result from in situ fragmentation 

of quartz veins. Some additional complexity in the evolution and morphology of these 

277


“siliceous lines” is given by the frequently evident secondary accumulation of quartz on the 

relictic veins, which in cases make difficult to distinguish relictic features from newly formed 

levels that would better fit with the concept of “silcretes”. 

Concerning the “structured horizons” below the “stonelines”, field and analytical data 

indicate that they are not paleosols. Though the process of structuration is not so clear, it also 

seems to be associated to the existence of the relatively more resistant layers within the basalt. 

In the case of profiles with “nodular lines”, it seems that during the process of nodules 

development, the material in between and immediately below gets a polyhedric structure. In 

this process of aggregates development, the “lines” seem to play as a sort of “protection” 

against the weathering front. This “protective” effect would be the origin of structuration in 

the case of “siliceous lines”. Several field evidences seem to support these interpretations: in 

many cases the “structured horizons” conserve many morphological features from the 

saprolite. In the cases where the “nodular” or “siliceous” lines have subhorizontal directions 

or when they bifurcate, “structured horizons” follow the orientation of those gravelly “lines”. 

Moreover, in the cases where the horizontal gravelly “lines” are interrupted, a feature that 

may be interpreted as the result of weathering proceeding through pockets into the parent 

rock, the “structured horizons” also disappear. 

Thus, both types of gravelly ”lines” identified in the ferrallitic soils of Misiones as well 

as the “structured horizons” are considering to be in situ relictic features deriving from the 

ferrallitic weathering of two types of basaltic flows appearing in the area. The soils showing 

both types of “stone lines” superposed within the same profile, the “nodular” one above the 

“siliceous” one -as was consistently observed up to the moment- in agreement with the usual 

lying of both types of basalt layers at the surface, are additional evidences of its 

autochthonous origin. 

ACKNOWLEDGMENTS 

The authors thank the Ägencia Nacional de Promoción de la Investigación Científica y 

Técnica¨ –ANPCyT- of Argentina, for supporting a great part of this research through the 

Project PICT 07-08879. 

REFERENCES 

[1] H. Behling, M, Lichte, A., Miklós. Evidence of a forest free landscape under dry and cold climate conditions 

during the Last Glacial Maximun in the Botocatu region (Sao Paulo State), Southeastern Brazil. Quaternary of 

South America and Antartic Peninsula, 11, 99-110, (1998). 

[2] H. Causevic, H. Morrás, A. Mijovilovich, C. Saragovi. Evidences of the stability of magnetite on a soil from 

Northeastern Argentina by Mössbauer spectroscopy and magnetization measurementes. Physica B: Physics of 

Condensed Matter, 354 (1-4): 373-376, (2004) 

[3] Y. Chatelin, Influence des conceptions géomorphologiques et paléoclimatiques sur línterpretation de la 

genèse et la classification des sols ferrallitiques dÁfrique Centrale et Australe. Cah. ORSTOM, sér. Pédol., 

V(3): 243-255, (1967) 

[4] H. Eswaran, G. Stoops. Surface textures of quartz in tropical soils. Soil Science Society of America Journal. 

43(2):420-424, (1979). 

[5] M. Iriondo, D. Kröhling. The tropical loess. Proc. 30 th International Geological Congress, (An Zhisheng et 

al., Eds.), Vol. 21, p. 61-77, (1997). 

[6] T. Desjardins, F. Andreux, B. Volkoff., C. Cerri, Distribution de l’ isotope 13 C dans des sols ferrallitiques du 

Brésil. Cah. ORSTOM, sér. Pédol., XXVI (4): 343-348, (1991). 

[7] D. Johnson. Dynamic denudation evolution of tropical, subtropical and temperate landscapes with three 

tiered soils: toward a general theory of landscape evolution. Quaternary International, 17: 67-78, (1993). 

278


[8] D. Johnson, J. Domier, D.N. Johnson. Animating the biodynamics of soil thickness using process vector 

analysis: a dynamic denudation approach to soil formation. Geomorphology, 67, 23-46, (2005). 

[9] L. Le Ribault. Léxoscopie des quartz. Masson, Paris, 150 p, (1977) 

[10] M. Lichte, H. Behling, Dry and cold climatic conditions in the formation of the present landscape in 

Southeastern Brazil. Z. Geomorph. N.F., 43(3):341-358, (1999). 

[11] A. Mariotti. Le carbone 13 en abondance naturelle, traceur de la dynamique de la matière organique des sols 

et de l’évolution des paléoenvironments continentaux. Cah. ORSTOM, sér. Pédol., XXVI (4): 299-313, (1991). 

[12] A. Mijovilovich, H. Morrás, C. Saragovi, G. Santana, J. Fabris. Magnetic fraction of an Ultisol from 

Misiones, Argentina. Hyperfine Interactions, C, 3: 332-335, (1998) 

[13] H. Morrás, L. Moretti, G. Píccolo, W. Zech. Algunas observaciones sobre la composición y el origen del 

material edafizado y las líneas de piedra sobreyacentes a los basaltos de Misiones. Actas X Reunión Argentina de 

Sedimentología, San Luis, pp. 106-108, (2004) 

[14] H. Morrás, L. Moretti, G. Píccolo, W. Zech. New hypotheses and results about the origin of stonelines and 

subsurface structured horizons in ferrallitic soils of Misiones, Argentina. 2 nd Assembly of the European 

Geosciences Union, Vienna, Geophysical Research Abstracts, Vol. 7, 05522, (2005). 

[15] H. Morrás, L. Moretti, B. Glaser, G. Píccolo, W. Zech. Eolian transport vs. in situ weathering: evidences for 

supporting an autochthonous origin of ferrallitic soil parent materials in subtropical norhteastern Argentina. 

Abstracts, INQUA International Workshop, Lower Latitudes Loess - Dust transport. Past and Present, 

Lanzarote, Canary Islands, (2006) 

[16] H. Morrás, L. Moretti, B. Glaser, G. Píccolo, C. Hatté, W. Zech. Paleoenvironments in the subtropical 

northeastern Argentina as deduced from stable Carbon isotopes composition of ferrallitic soils. V South 

American Symposium on Isotope Geology. Punta del Este, Uruguay, pp. 267-271, (2006) 

[17] L. Pessenda, S. Gouveia, R. Aravena, R. Boulet, E. Valencia. Holocene fire and vegetation changes in 

southeastern Brazil as deduced from fossil charcoal and soil carbon isotopes. Quaternary International, 114, 35– 

43, (2004). 

[18] G. Sanesi. I souli di Misiones. Academia Italiana di Scienze Forestali, 343 p., (1965). 

[19] P. Ségalen. Les sols ferrallitiques et leur répartition géographique. Orstom Éditions, Paris, Tome 1, 198 p., 

(1994). 

[20] G. Stoops. Le profil dálteration au Bas-Congo (Kinshasa). Sa description et sa genèse. Pédologie, XVII (1): 

60-105, (1967). 

279


Figure 5. A: soil profile with a ¨nodular line¨ (profile M0 in the locality of Leandro N. Alem); see the 

complex morphology of the ¨line¨. B: a profile with a ¨siliceous line¨ (M10, in the locality of 

Aristóbulo del Valle). C: goethitic nodules developing in the saprolite, and giving rise to a ¨nodular 

line¨. D: vertical view of a ¨siliceous line¨ deriving from a quartz vein into the basalt; E: at left, two 

superposed weathered basalt layers; the lower layer includes quartz veins; at right, the same profile in 

a more advanced step of weathering. F: the same sequence of basalt layers showed in figure E, 

already pedogenized; remark the superposition of a ¨nodular line¨ above a ¨siliceous line¨, each one 

with its own ¨structured horizon¨ G: sand fraction from a Bt horizon, composed by magnetite, quartz 

and pseudosands (optical microscopy); remark the presence of very weathered quartz grains together 

with secondary quartz. H: a grain of secondary quartz from the sand fraction; remark the dissolution 

pits. 

280


PEDOGENESIS ALONG A HILLSLOPE TRAVERSE IN THE 

UPPER AFRAM BASIN, GHANA 

T. Adjei-Gyapong, 1 E. Boateng, 1 * C. Dela Dedzoe, 1 W.R. Effland, 2 M.D. Mays 2 and J.K. 

Seneya 1 


1 Ghana Soil Research Institute and 2 USDA/NRCS Soil Survey Division 

E-mail: soilri@ncs.com.gh, Tel: 23321778226, Fax: 23321778219 

In March 2004, six pedons were sampled during a collaborative Ghana-U.S. inter-laboratory 

soil characterization project. This poster presents results from three pedons located along a 

hillslope traverse. The objectives of this research are: (1) to compare the morphology of the 

soils; (2) to examine the chemical, physical and mineralogical composition of each soil; and 

(3) to understand the genesis and variation of soil properties along the hillslope. 

Three locations were selected to represent soil variation along a hillslope traverse with 

consistent parent materials, climate, and native vegetation. Standard soil characterization 

analyses were conducted at the USDA/NRCS National Soil Survey Laboratory in Lincoln, 

NE (Soil Survey Staff, 1996),and the Soil Research Institute , Ghana. Analytical results for 

particle size distribution, pH, clay and sand mineralogy, and citrate-dithionite extractable 

“free” Fe are discussed. Thin sections were prepared from oriented clods 

The soils are developed over relatively similar parent materials (fine-grained Voltaian 

sandstones) and in similar macro-climates. Occurring at the forest-savannah transition, they 

display contrasting morphological properties, which affect their soil classification, land use 

and management. The Techiman series (Typic Rhodustalfs) on the summit to shoulder is well 

to excessively drained, moderately deep (80-100 cm), grayish brown, loamy fine sand with 

many (35%) ironstone concretions and nodules over a reddish brown, dominantly ironstoneconcretionary 

(65%) sandy clay loam subsoil. On the linear (middle) back slopes, the 

Amantin series (Typic Kandiustalfs) is moderately well drained, very deep (> 190 cm), 

grayish brown, loamy fine sand over yellowish brown sandy clay loam free of coarse 

fragments. The Denteso series (Oxyaquic Dystrudept) on the foot (lower) slope is poorly 

drained, grayish brown, loamy fine sand over structureless, single-grained pinkish gray sand. 

Iron concretions and ironpans occur within, and in some cases beneath, the soils 

studied along the hillslope in the Upper Afram Basin. The genesis of ironpans involves cycles 

of Fe mobilization, redistribution and concentration within the landscape. The higher Fe 

content results from element release through mineral weathering from overlying horizons and 

neighboring upslope soils. 

Further research is planned with an evaluation of terrain data on elevation, slope 

classes, slope aspect and other derivatives for the Afram Basin study area. 

Current environmental conditions (elevation, slope classes, aspect) within the Afram 

Basin study area are displayed with derivatives from a 200 ft resolution digital elevation 

model (DEM). 

REFERENCES 

[157] S.V. Adu, J. A. Mensah-Ansah. "Soils of the Afram Basin, Ashantiand Eastern Regions, Ghana", 

CSIR-Soil Research Institute, Memoir No. 12. Kwadaso-Kumasi, Ghana. 90pp., (1995). 

281


[158] T.W. Awadzi, R.D. Asiamah. "Soil Survey of Ghana", Soil Survey Horizon. 43 (2): 44-52, (2002). 

[159] E. Boateng, TR. E. Chidley, D. J. Savory, J. Elgy. "Soil Information System Development and Land 

Suitability Mapping at the Ghana Soil Research Institute", Poster Presentation at 16 th World Congress of Soil 

Science, Montpellier, France. August 20-26, (1998). 

[160] Soil Survey Staff. "Soil Survey Laboratory Methods Manual". USDA/NRCS Soil Survey 

Investigations Report No. 42, January, (1996). 

282


INFLUENCE OF TITANOMAGNETITE ON DITHIONITE- 

CITRATE-BICARBONATE (DCB) AND OXALATE 

EXTRACTIONS IN WEATHERED DOLERITE 

C. G. Algoe 1* , E. Van Ranst 2 , G. Stoops 3 

1* Anton de Kom Universiteit van Suriname, Faculteit der Technologische Wetenschappen, POB 9212, 

Paramaribo, Suriname, Tel: +597 465558 ext. 413, Fax: +597 495005, Email: c.algoe@uvs.edu 

2 Laboratorium voor Bodemkunde, Universiteit Gent, Krijgslaan 281, S8, B-9000 Gent, Belgium 

3 Laboratorium voor Mineralogie, Petrologie en Micropedologie, Universiteit Gent, Krijgslaan 281, S8 B-9000 

Gent, Belgium 

Abstract 

Four dolerite boulders were collected in weathered profiles in the Precambrian Guiana Shield 

occurring in Suriname. These spheroidally weathered boulders were sub-sampled in the 

laboratory to obtain shells of different weathering grades, which were analysed using 

chemical and mineralogical techniques. The high amount of ammonium-oxalate extractable 

iron as compared to the dithionite-citrate-bicarbonate (DCB) extractable iron and the presence 

of titanomagnetite in the fresh rock questions the influence of (titano)magnetite on either type 

of extraction technique. Highly magnetic fractions were separated from the fresh rock and 

studied using microprobe analyses, oxalate and DCB extractions. Oxalate and DCB 

extractions were also carried out on thin sections. The results confirm the influence of 

titanomagnetite on the extractable iron content. 

INTRODUCTION 

Two techniques are most commonly used to extract pedogenic iron from soil and regolith 

samples: the ammonium-oxalate method (Ox) and the dithionite-citrate-bicarbonate (DCB) 

method. The oxalate extraction is presumed to remove X-ray amorphous and organic bound 

iron oxides, whereas the dithionite extraction is supposed to remove in addition the finely 

crystalline iron oxides [9, 10, 21]. The amount of iron released by the dithionite extraction 

should therefore be equal to or greater than the amount of iron released by the oxalate 

extraction method [21]. 

In order to study the spheroidal weathering of dolerite, four boulders were collected in 

a weathered profile within the Precambrian Guiana Shield occurring in Suriname. These 

boulders were sub-sampled in the laboratory, to obtain shells of varying weathering grade, 

which were analyzed with various chemical and mineralogical techniques, among which the 

oxalate and DCB extractions. The amount of iron extracted by the ammonium-oxalate method 

was unexpectedly higher than the amount of Fe extracted by the DCB method carried out on 

fresh rock (Table 1). One of the possible explanations for this result could be the presence of 

magnetic minerals in the samples, influencing the extraction methods. This study aims at 

determining the influence of magnetic minerals on the ammonium oxalate extractable and 

DCB extractable iron. Analyses are made on bulk samples as well as thin sections of the fresh 

rock. 

A number of studies have been dedicated to investigate the influence of magnetite on 

both the dithionite and oxalate extraction methods. The results are sometimes however a bit 

contradictory. It has been demonstrated that oxalate extraction dissolves magnetite and that 

283


dithionite extraction does not attack primary magnetite [10] but does attack hematite in or on 

the magnetic grains [19, 20, 21]. Other studies however reveal that the presence of magnetite 

or maghemite does influence the DCB extraction method [4, 5, 6, 7, 8]. 

DCB extraction depends on the extraction temperature, as well as on the concentration 

of the magnetic minerals [18]. Athough some distinction between fine grained maghemite and 

magnetite could be made the DCB extraction treatment alone was proven not to be suitable 

for distinction between fine-grained magnetic iron oxides [18]. 

It was stated [18] that the results of reported DCB extraction studies varied 

considerably. In some cases the DCB method was reported to dissolve only the pedogenic 

maghemite [5, 16, 17] while in other cases the fine-grained magnetite was dissolved as well 

[8]. The results of different studies were found difficult to compare, because the extraction 

procedure of each study was not always clearly specified. Factors such as amount of sample, 

type of sample, amount of dithionite and extraction temperature varied with each study. 

The reductive dissolution of iron oxides is a kinetic process and factors such as pH, 

crystallinity and temperature have a major effect on the dissolution rate [11, 13, 22]. 

Therefore, results of extraction studies with differences in extraction procedures do not 

necessarily reflect the same dissolution behaviour. The sample type (natural or synthetic) also 

determines the results obtained by DCB extraction. 

Chemical extractants, including acid ammonium oxalate and DCB, have also been 

used for studying the spatial distribution of iron and other oxides in thin sections of 

undisturbed soil [1, 2, 3], proving the usefulness for these techniques for extractions carried 

out on thin sections. 


The material selected for this study consisted of dolerite samples obtained in the 

Central-North area of Suriname in a village called Berg en Dal (Figure 1). The dolerite 

boulders showing spheroidal weathering patterns were collected in the field and shells were 

sub-sampled in the laboratory. For this study samples of the unweathered dolerite were 

selected for analyses. Ammonium-oxalate extractions and DCB extractions were carried out 

on bulk samples, their highly magnetic fraction, and on thin sections. The highly magnetic 

fraction was separated from the bulk sample by passing a hand magnet over the sample at a 

distance of 1 cm. The highly magnetic fraction was studied using microprobe analyses, 

ammonium-oxalate extractions, DCB extractions, and X-Ray analyses. The extracts were 

measured using atomic absorption spectrophotometry (AAS). 

The ammonium oxalate extraction is based on solubilisation of the amorphous 

sesquioxides after reduction reactions with ammonium oxalate in the dark. The method 

followed was retested by Schwertmann [14, 15] who found out that in the darkness the 

ammonium-oxalate extraction only dissolved X-ray amorphous oxides [9]. Fe, Al, Si and Mn 

are measured by atomic absorption spectrophotometry (AAS). A 0.2M ammonium oxalate 

solution and a 0.2M oxalic acid solution were prepared and mixed to obtain an ammonium 

oxalate-and oxalic acid mixture with pH = 3. The sample (250 mg) was weighed in a plastic 

centrifuge tube to which 50 ml ammonium oxalate mixture was added. This mixture was 

stirred in the dark for 4 hours and centrifuged during 10 minutes at 2000 rpm. The supernatant 

clear solution was decanted to a volumetric flask of 50 ml and the volume was made up with 

the oxalate mixture. This solution was used for the measurement of Fe, Al, Si and Mn. The 

same procedure was followed for extraction of thin sections, varying the extraction time from 

4 to 6, and finally 12 hours [1, 2, 3]. 

284


Figure 1: Location of the study area Berg en Dal in Suriname (Modified after [12]) 

285


Using the DCB extractions, amorphous coatings and crystals of free iron oxides and 

other sesquioxides are removed using sodiumdithionite as reducing agent. The removal of free 

iron oxides aids in dispersion of the silicate proportion [11]. The DCB extractions were 

carried out following the procedure outlined by Mehra and Jackson [11]. The concentration of 

Fe, Al, Si and Mn are determined from a solution in which the solubilized cations are kept in 

solution by complexation with Na citrate. A Na citrate bicarbonate buffer is added to the 

sample, which is placed in a waterbath, for 20 minutes after which sodium dithionite powder 

(0.75 gram) is added, while stirring and the solution is again left for 20 minutes. After 

cooling, the mixture is centrifuged at 3000 rpm, decanted, washed, again centrifuged and 

decanted. The collected extraction solution is used for determination of Fe, Al, Si and Mn 

using AAS. The same procedure was followed for DCB extraction on thin sections. In some 

cases multiple DCB extractions were carried out on the same thin section. The total values for 

Fe, Al, Si and Mn were measured for the fresh rock using AAS. 

The mineralogical composition of the opaque minerals was determined by wavelength 

dispersive spectrometry (WDS) microprobe analyses on uncovered thin sections and Energy 

dispersive spectrometry (EDS) microprobe analyses on magnetic grains, as well as X-Ray 

Diffraction analyses on the highly magnetic fraction. The XRD patterns were collected with a 

Phillips X’PERT system with a PW 3710 based diffractometer (Laboratory of Soil Science, 

Ghent University), equipped with a Cu tube anode, a secondary graphite beam 

monochromator, a proportional xenon-filled detector, and a 35-position multiple sample 

changer. The incident beam was automatically collimated. The irradiated length was 12 mm. 

The secondary beam side comprised a 0.1 mm receiving slit, a soller slit, and a 1° anti-scatter 

slit. The tube was operated at 40 kV and 30 mA, and the XRD data were collected in a θ/2θ 

geometry from 3° 2θ onwards, with a step of 0.02° 2-theta and a count time of 1 second per 

step. The highly magnetic samples were analysed using unoriented powder samples (3° to 60° 

2θ) that were placed on a glass plate using collodium solution. 


Mineralogical composition - Microprobe analyses 

In order to determine the composition of the opaque minerals, 12 WDS microprobe analyses 

were carried out in thin sections. All analysed grains are Fe-Ti oxides. Three analyses gave 

Fe/Ti ratios equal to 1, pointing to an ilmenite composition (FeTiO3). For the remaining 

analyses, the Fe/Ti ratio was close to 2, which is compatible with an ulvospinel composition 

(Fe2TiO4). Investigation of the opaque grains at a magnification of 400 times shows the 

intergrowth of ulvospinel in a mass of ilmenite. EDS microprobe analyses of the highly 

magnetic fraction give similar results, and point to an ulvospinel composition. 

Mineralogical composition – X-Ray Diffraction 

The mineralogical composition of the highly magnetic fraction was determined using X-ray 

diffraction. The X-Ray diffraction pattern obtained is presented in Figure 2. The peaks 

indicate the presence of spinel, magnetite and/or (titanian) maghemite. The peaks do not 

indicate the presence of ilmenite. 

286


Oxalate and DCB extraction on samples 

Table 1 shows the results of the extractions carried out on the samples. The higher amounts of 

oxalate extractable iron in the bulk samples as apposed to the amounts of DCB extractable 

iron are clear. The same can be stated for Al2O3. In order to infer whether the difference can 

be attributed to the presence of magnetic minerals in the fresh rock, the analyses were 

repeated on magnetic fractions. 

Intensity 

400 

350 

300 

250 

200 

150 

100 

50 

0 

0.483 Sp/Mt/Mgt 

0.374 Mgt 

0.336 Mgt 

0.322 u 

0.318 u 


0.275 Ilm/Mgt 


15 18 21 24 27 30 33 36 39 42 45 48 51 54 57 60 

287 


2θ 

0.223 Mgt 

0.214 u 


Figure 2: XRD Diffraction pattern for highly magnetic samples , Sp: Spinel, Mt: Magnetite, Mgt: 

maghemite, U: Unidentified 

DB1-C: Bulk Sample DB1-C: highly magnetic sample 

Wt % 

Fe2O3DCB 1.73 4.64 

Fe2O3OX 3.91 12.42 

Fe2O3-total 15.60 - 

Al2O3DCB 0.18 0.14 

Al2O3OX 0.52 0.31 

Al2O3-total 12.80 - 

MnO2DCB 0.01 0.01 

MnO2OX 0.01 0.02 

MnO2-total 0.23 - 

SiO2DCB 0.90 0.32 

SiO2Ox 0.49 0.27 

SiO2-total 48.90 - 

Table 1: Total oxide values, ammonium-oxalate and DCB extractable oxides in bulk and magnetic 

samples 

0.187 u 

0.172 Sp/Mt 

0.161 Sp/Mgt


Figure 3: Image of untreated section (A), ammonium-oxalate treated section (B) and DCB treated 

section (C) 

The results indicate that the oxalate extractable Fe and to some extend Al are much higher 

than the DCB extractable ones. 

Oxalate and DCB extractions on thin sections 

After treatment of the thin sections digital photographs were taken in order to visually detect 

changes in the minerals present. Figure 3 gives three photomicrographs of the fresh rock, one 

before treatment (A), one after 4 hours of oxalate treatment (B) and one after DCB treatment 

(C), each taken in plain polarised light. 

The fresh rock is composed of predominantly lathshaped plagioclases which are 

colourless and bright in the pictures. The second most abundant are the pyroxenes, which are 

also colourless but have higher relief as compared to the plagioclases. The treatments were 

focused on the black opaque grains of either ulvospinel or ilmenite composition. 

After the ammonium-oxalate treatment the thin section appears brighter. The opaque 

grains show no visible changes. There is however the appearance of a black spot (outlined 

with an ellipse) that was not present in the untreated sample. After DCB treatment the section 

is far less bright, the black spot is no longer present and no changes have been noticed in the 

opaque grains. The DCB and oxalate extractions on thin sections of fresh rock material did 

not show any sign of mineral dissolution. For this reason the oxalate extraction period was 

extended to 6, 8 and 12 hours, however still without signs of apparent dissolution. 

CONCLUSIONS AND DISCUSSION 

This study demonstrates that the amount of oxalate extractable Fe was much greater than the 

DCB extractable Fe. These differences are even more pronounced in the magnetic fraction 

288


suggesting influence from the magnetic fraction. The XRD pattern of the magnetic fraction 

point to the presence of magnetite, spinel or maghemite. The percentage of the magnetic 

fraction was however not determined. The data presented does suggest attack of the magnetic 

mineral (ulvospinel) by the oxalate solution. The higher values for DCB extractable iron 

measured in the magnetic fraction, also point to attack of the magnetic grains by the DCB 

extraction technique. This means that Fe values obtained from samples containing a magnetic 

mineral (magnetite or ulvospinel) can be overestimated. The XRD pattern of the magnetic 

fraction did not point to the presence of ilmenite, and consequently the influence of ilmenite 

was not investigated. Although this is apparent in the chemical data the extractions on the thin 

sections do not reveal attack or dissolution of the opaque (and possibly magnetic) mineral. A 

possible dissolution of the opaque grains should be confirmed by studying the thin sections 

using scanning electron microscopy and microprobe analyses before and after treatment. This 

would also investigate the influence of ilmenite on the extraction techniques. 

REFERENCES 

[1] J.M. Arocena, G. De Geyter, C. Landuyt and U. Schwertmann. “Dissolution of soil iron oxides with 

ammoniumoxalate: comparison between bulk samples and thin sections”. Pedologie, 29, pp. 275-297, (1989) 

[2] J.M. Arocena, G. De Geyter, C. Landuyt and G. Stoops. “A Study on the Distribution and Extraction of Iron 

and Manganese in soil thin sections”. In: Douglas L.A (ed.). Soil Micromorphology: A Basic and Applied 

Science. Elsevier, Amsterdam, pp. 621-626, (1990) 

[3] P. Bullock, P.J. Loveland and C.P. Murphy. “A technique for selective solution of iron oxides in thin sections 

of soil”. Journal of Soil Science, 26: 247-248, (1975). 

[4] P. Fine, and M.J. Singer. “Pedogenic factors affecting magnetic susceptibility of northern California soils”, 

Soil Science Society of America Journal, 53, pp. 1119-1127, (1989). 

[5] P. Fine, M.J. Singer, R. La Ven, K.L. Verosub and R.J. Southard. “Role of pedogenesis in distribution of 

magnetic susceptibility in two California chronosequences”, Geoderma, 44, pp. 287-306, (1989). 

[6] P. Fine,. M.J. Singer and K.L. Verosub. “Use of magnetic susceptibility measurement in assessing soil 

uniformity in chronosequence studies”, Soil Science Society of America Journal, 56, pp. 1195-1199, (1992). 

[7] P. Fine, M.J. Singer, K.L. Verosub and J. TenPas. “New evidence for the origin of ferrimagnetic minerals in 

loess from China”, Soil Science Society of America Journa, 57, pp. 1537-1542, (1993). 

[8] C.P. Hunt, M.J. Singer, G. Kletetschka, J. TenPas and K.L. Verosub. “Effect of citrate–bicarbonate– 

dithionite treatment on fine-grained magnetite and maghemite”, Earth and Planetary Science Letters, 130, pp. 

87–94, (1995). 

[9] J.A. McKeague, and J. H. Day. “Dithionite and oxalate extractable Fe and Al as aids in differentiating 

various classes of soils”, Canadian Journal of Soil Science, 46, pp. 13-22, (1966). 

[10] J.A. McKeague, J.E. Brydon and N.M. Miles. “Differentiation of forms of extractable iron and aluminium 

in soils”, Soil Science Society of America Proceedings, 35, pp. 33-38, (1971). 

[11] O.P. Mehra, and M.L. Jackson. “Iron oxide removal from soils and clays by a dithionite–citrate system 

buffered with sodium bicarbonate”, Clays and Clay Minerals., 7, pp. 317–327, (1960). 

[12] Narena-Celos. Suriname kaarten collectie, 1p., (2004). 

[13] D. Postma. “The reactivity of iron oxides in sediments: a kinetic approach” Geochimica Cosmochimica 

Acta, 57, pp. 5027–5034, (1993). 

[14] U. Schwertmann. “Differenzierung der Eisenoxide des Bodens durch photochemische Extraktion mit saurer 

Ammoniumoxalat-Lösung”. Z. Pflanzenernähr. Düng., Bodenkunde, 105, pp. 194-202, (1964). 

[15] U. Schwertmann. “Use of oxalate for Fe extraction from soils”. Canadian Journal of Soil Science., 53: pp. 

244-246, (1973) 

[16] M.J. Singer and P. Fine. “Pedogenic factors affecting magnetic susceptibility of Northern California soils”, 

Soil Science Society of America Journal, 53, pp. 1119–1127, (1989). 

[17] M.J. Singer, L.H. Bowen, K.L. Verosub, P. Fine and J. TenPas. “Mössbauer spectroscopic evidence for 

citrate–bicarbonate–dithionite extraction of maghemite from soils”, Clays and Clay Minerals, 43, pp. 1-7, 

(1995). 

[18] I.H.M. van Oorschot, and M.J.Dekkers. “Dissolution behaviour of fine-grained magnetite and maghemite in 

the citrate–bicarbonate–dithionite extraction method”, Earth and Planetary Science Letters, 167, pp. 283–295, 

(1999). 

289


[19] I.H.M. van Oorschot and Mark J. Dekkers. “Selective dissolution of magnetic iron oxides in the acid– 

ammonium oxalate/ferrous iron extraction method—I. Synthetic samples, Geophysical Journal International, 

145, pp. 740–748, (2001). 

[20] I.H.M. van Oorschot, M. J. Dekkers and P. Havlicek,. Selective dissolution of magnetic iron oxides with the 

acid-ammonium-oxalate/ferrous-iron extraction technique—II. Natural loess and palaeosol samples . 

Geophyisical Journal International, 149, pp. 106–117, (2002). 

[21] A.L. Walker. “The effects of magnetite on oxalate and dithionite extractable iron”, Soil Science Society of 

America Journal, 47, pp. 1022-1026, (1983). 

[22] B. Zinder, G. Furrer and W. Stumm. “The coordination chemistry of weathering, II. Dissolution of Fe(III) 

oxides”, Geochimica Cosmochimica Acta, 50, pp. 1861–1869, (1986). 

290


Sub-theme : DEVELOPMENTS IN SOIL MICROMORPHOLOGY 

Abstract 

Stoops, G., Marcelino, V., Mees, F. 

Department of Geology and Soil Science, Ghent University, Gent, Belgium 

This contribution brings an overview of latest research in soil micromorphology conducted at 

the Department of Geology and Soil Science of the Ghent University, and a short introduction 

to two important current themes in this field. 

INTRODUCTION 

Although soil microscopy has been totally excluded from the new curriculum of “Physical 

Land Resources” studies in Ghent, research in this field is still being continued. 

Apart from applications of micromorphological techniques to soil genesis and 

development [1-23] and to archaeology (the latter especially by Prof. R. Langohr and coworkers), 

attention has also been paid to the development and/or critical evaluation of special 

methodologies such as image analysis and X-ray-tomography, and observation and 

description techniques. A book on genetic interpretation of micromorphological data is in 

progress (Stoops et al.). 

APPLICATIONS IN SOIL GENESIS AND DEVELOPMENT 

Amongst the applications in soil genesis and development the following will be summarised: 

1° circumgranalar bassanite formation around quartz grains in a natural gypsum crust. 

Heating experiments suggest that differences in heat capacity between the components can 

explain the observed patterns, but in the natural crust they were found to be related to the 

availability of space around the enclosed detrital mineral grains. Coatings of the studied type, 

or derived relict features, are potential palaeosurface indicators [9]. 

2° zeolite neoformation in the Olduvai (Tanzania) stratigraphic sequence of lacustrine and 

fluvial sediments, related to the interaction of volcanic material with saline alkaline lake water 

or groundwater [10]. The conditions formation of the various zeolite minerals were 

investigated (analcime, chabazite, phillipsite, erionite, clinoptilolite), based on their mode of 

occurrence, including their relationship with other pedogenic materials. 

3° differentiation of pedogenic and geogenic calcite in soils from Iran, using UV and blue 

light fluorescence techniques combined with cathodoluminescence [7]. 

4° impact of land use (forest, afforested pasture and crop land) and seasonal freezing on the 

(micro)morphological properties of silty Norwegian soils [20]: platy and lenticular 

microstructures due to frost are present in the upper part of all soils studied but occur at 

shallowest depth (35 cm) under forest than in the other soils (50 cm); planar voids associated 

with these structures are not or partially accommodating, meaning that when the soil is wet 

they do not completely close and water can still move parallel to the soil surface. Dusty clay 

coatings (agricutans) and infillings and compound layered infillings are observed immediately 

below the plough layer in the cropland but not at the same depth in the other soils. They thus 

reflect the increased internal soil erosion associated with cultivation. 

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5° soil evolution on volcanic ash in Europe [19, 22]: as a first step coatings of fine material 

develop around the coarse particles (chitonic c/f related distribution pattern), or form hypocoatings 

in the case of pumice; with increasing amount of fine material an enaulic c/f r.d.p. is 

formed, that gradually grades into a fine granular microstructure. The latter is preserved as an 

intrapedal microstructure in the more clayey Bw horizons where a (sub)angular blocky 

microstructure prevails. In the case of Icelandic soils a lenticular microstructure developed, 

related to freeze-thaw cycles [21] and a microstratification, often with organic layers, is 

throughout preserved, pointing to the quasi absence of biological activity, in contrast to what 

happens in temperate and tropical areas [1]. The transformation of volcanic glass to 

alteromorphs of allophane, with a palagonite like appearance, is discussed [2]. Throughout the 

profiles an undifferentiated b-fabric is noticed in the fine mass of the European soils on 

volcanic ash. Alteration products of volcanic ash in Mexico give rise to specific opaline 

features [3, 4]. 

6° research on micromorphological concepts and terminology lead to the publication of a new 

manual [19], in order to replace the standard work of Bullock et al. (1985) out of print since 

many years. 

IMAGE ANALYSIS 

Presently, low-cost software-based image analysis systems make automated analysis of soil 

pore space and other features very attractive. Large amounts of data on feature characteristics 

can be easily generated. Although it is currently possible to use 3D image analysis associated 

with non-destructive tools such as X-ray CT to observe and quantify soil porosity, 2D image 

analysis procedures are still commonly applied because of their lower cost and easier 

accessibility. With the aim of investigating whether different sorts of images analysed with 

different methods produce comparable results, three widely used sample preparation and 

image acquisition procedures and three 2D-image analysis methods with different levels of 

manual intervention were compared. The quality of the image, determined by the image 

acquisition and sample preparation method used, affects average porosity measurements 

significantly: fluorescent images compared with BSE-images clearly underestimate porosity. 

On the other hand, different interventions and methods used to increase image quality and to 

segment images also affect porosity measurements significantly. Moreover, in the particular 

case of manual thresholding, porosity values obtained by the same observer are more 

reproducible than those from different observers. These results stress the need for 

standardization of image analysis protocols and warn of the dangers of comparing soil 

porosity measurements performed on different types of images. 

X-RAY TOMOGRAPHY 

X-ray computed tomography (X-ray CT) is a non-destructive imaging technique that provides 

information about the internal structure of objects. X-ray CT images are obtained by 

recording radiographs for successive positions during step-wise rotation of a sample relative 

to an X-ray source and a detector. These radiographs are then used to create images showing 

variations in X-ray attenuation values, determined by density and element composition, for 

cross-sections perpendicular to the axis of rotation. One of the advantages of X-ray CT is the 

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possibility of obtaining a large number of parallel cross-sections, which can be used for 3D 

imaging and analysis. 

Since its development as a medical technique, X-ray CT has been applied in various 

other fields of research, including earth sciences and engineering (e.g. [28]). In soil science, it 

has mainly been used for the study of pore characteristics. Aspects of soil porosity that have 

been investigated with X-ray CT include the effects of faunal activity (e.g. [24]), soil 

compaction (e.g. [27]), erosion control measures (e.g. [31]), and tillage practices (e.g. [30]). 

Examples of other applications are the study of root development (e.g. [26]), water movement 

(e.g. [25]), and soil surface morphology (e.g. [25]). 

Ghent University has X-ray CT facilities for material research, operated by the 

Department of Geology and Soil Science and the Department of Subatomic and Radiation 

Physics. The available scanners can handle a wide range of sample types, for studies 

requiring CT images with specific requirements regarding spatial resolution and material 

contrasts. 

REFERENCES 

Most important micromorphological contributions from the Department of Geology and Soil 

Science over the last five years 

[1] Fauzi, A.I., Stoops, G. Influence of Krakatau ash fall on pedogenesis in West Java. Example of a 

toposequence in the Honje Mountains, Ujung Kulon Peninsula, Catena, 56, 45-66, (2004). 

[2] Gérard, M., Caquineau, S., Pinheiro, J., G. Stoops. Weathering and allophane neoformation in soils on 

volcanic ash from the Azores, Europ. J. Soil Sci.(in press). 

[3] Gutierrez Castorena, M.d.C., Stoops, G., Ortiz Solorio, C.A., Lopez Avila, G. Amorphous silica materials in 

soils and sediments of the Ex-Lago de Texcoco, Mexico. An explanation of its subsidence, Catena, 60, 205-226, 

(2005). 

[4] Gutierrez Castorena, M.d.C., Stoops, G., Ortiz Solorio, C.A., Sanchez-Guzman, P. Micromorphology of 

opaline features in soils on the sediments of the Ex-Lago de Texcoco, Mexico, Geoderma, 132, 89-104, (2005). 

[5] Heidari, A., Mahmoodi, Sh., Stoops, G., Mees, F. Micromorphological characteristics of Vertisols in Iran, 

including non-smectitic soils, Arid Land Research and Management, 19, 29-46, (2005). 

[6] Khormali, F., Abtahi, A., Mahmoodi, S., Stoops, G. Argillic horizon development in calcareous soils of arid 

and semi-arid regions of southern Iran, Catena, 53, 273-301, (2003). 

[7] Khormali, F., Abtahi, A., Stoops, G.. Micromorphology of calcitic features in highly calcareous soils of Fars 

Province, Southern Iran, Geoderma, 132, 31-46, (2006). 

[8] Marcelino V., Cnudde V., Vansteelandt S., Carò F.. An evaluation of 2D-image analysis techniques for 

measuring soil microporosity, European Journal of Soil Science (in press). (2006). 

[9] Mees, F., Stoops, G. Circumgranular bassanite in a gypsum crust from eastern Algeria - a potential 

palaeosurface indicator, Sedimentology, 50, 1139-1145, (2003). 

[10] Mees, F., Stoops, G., Van Ranst, E., Paepe, R., Van Overloop, E. The nature of zeolite occurrences in 

deposits of the Olduvai Basin, northern Tanzania, Clays and Clay Minerals, 53,659-673,. (2005). 

[11] Mees, F., De Dapper, M. Vertical variations in bassanite distribution patterns in near-surface sediments, 

southern Egypt, Sedimentary Geology, 181, 225-229, (2005). 

[12] Mees, F. Salt mineral distribution patterns in soils of the Otjomongwa pan, Namibia, Catena, 54, 425-437, 

(2003). 

[13] Mees, F., Singer, A. Surface crusts on soils/sediments of the southern Aral Sea basin, Uzbekistan, 

Geoderma, (in press). 

[14] Mulyanto, B., Stoops, G.. Mineral neoformation in pore spaces during alteration and weathering of andesitic 

rocks in humid tropical Indonesia, Catena, 54, 385-392, (2003). 

[15] Oleschko, K., Parrot, J-F., Ronquillo, G., Shoba, S., Stoops,, G. Marcelino, V. Weathering: towards a fractal 

quantifying,. Mathematical Geology,. 51: 607-627, (2004). 

[16] Stoops, G., Van Ranst, E., Verbeek, K. Pedology of soils within the spray zone of the Victoria Falls 

(Zimbabwe), Catena, 46, 63-83, (2001). 

[17] Stoops, G.,. Achievements in micromorphology,. Catena, 54, 317-319, (2003). 

293


[18] Stoops, G. Guidelines for the Analysis and Description of Soil and Regolith Thin Sections. SSSA. Madison, 

WI., 184pp + CD. ISBN 0-89118-842-8, (2003). 

[19] Stoops, G., Gérard, M., Micromorphology. In: Arnalds, O., Bartoli, F., Buurman, P., Garcia-Rodeja, E., 

Oskarsson, H., Stoops, G. (eds), Soils of Volcanic Regions of Europe, (in press). 

[20] Stoops, G., D. Dedecker. Microscopy on undisturbed sediments as a help in planning dredging operations. 

A case study from Thailand. Proceedings International Conference Pnom Penh, KAOW. (in press). 

[21] Stoops, G., Gérard, M., Arnalds, O. A micromorphological study of andosol genesis in Iceland, Geoderma, 

(accepted). 

[22] Stoops.G. Micromorphology of soils on volcanic ash in Europe. A review and synthesis. Europ. J.Soil 

Science, (accepted). 

[23] Sveistrup T. E., Haraldsen T.K., Langohr R., Marcelino V., Kværner J.. Land use impact on seasonally 

frozen silty soils in South Eastern Norway, Soil and Tillage Research, 81: 39-56, (2005). 

Cited papers – X-ray tomography 

[161] Bastardie, F., Capowiez, Y., Cluzeau, D. 3D characterisation of earthworm burrow systems in natural 

soil cores collected from a 12-year-old pasture. Applied Soil Ecology 30, 34-46, (2005). 

[162] Fohrer, N., Berkenhagen, J., Hecker, J.M., Rudolph, A. Changing soil and surface conditions during 

rainfall - Single rainstorm/subsequent rainstorms, Catena, 37, 355-375, (1999). 

[163] Gregory, P.J., Hutchison, D.J., Read, D.B., Jenneson, P.M., Gilboy, W.B., Morton, E.J. Non-invasive 

imaging of roots with high resolution X-ray micro-tomography, Plant and Soil, 255, 351-359, (2003). 

[164] Langmaack, M., Schrader, S. & Rapp-Bernhardt, U., Kotzke, K. Soil structure rehabilitation of arable 

soil degraded by compaction, Geoderma, 105, 141-152, (2002). 

[165] Mees, F., Swennen, R., Van Geet, M., Jacobs, P. (eds). Applications of X-ray Computed Tomography 

in the Geosciences. Geological Society Special Publication 215, 328 pp. Geological Society Publishing 

House, Bath, United Kingdom. (2003). 

[166] Mooney, S.J. Three-dimensional visualization and quantification of soil macroporosity and water flow 

patterns using computed tomography, Soil Use and Management, 18, 142-151, (2002). 

[167] Pedrotti, A., Pauletto, E.A., Crestana, S., Holanda, F.S.R., Cruvinel, P.E., Vaz, C.M.P. Evaluation of 

bulk density of Albaqualf soil under different tillage systems using the volumetric ring and computerized 

tomography methods, Soil & Tillage Research, 80, 115-123, (2005). 

[168] Rachman, A., Anderson, S.H., Gantzer, C.J., Computed-tomographic measurement of soil 

macroporosity parameters as affected by stiff-stemmed grass hedges, Soil Science Society of America 

Journa, 69, 1609-1616, (2005). 

Some new publications on micromorphology 

[169] Eswaran, H., Drees, R. Soil under the Microscope: Evaluating Soil in Another Dimension. CD. Soil 

Micromorphology Committee of the Soil Science Society of America. 

[170] FitzPatrick, E.A., Soil Microscopy and Micromorphology. CD. Interactive Soil Science, 76 Burns Road, 

Aberdeen, AB15 4NS, UK, (2006) 

[171] Kapur, S., Mermut, A., Stoops, G., (Eds.), Special Issue of Geoderma (papers presented during the 

International Working Meeting on Soil Micromorphology, 2004, Adana, Turkey) (in preparation 

[172] Stoops, G. (Ed.), Achievements in Micromorphology. Special Issue of Catena, Vol. 54, Issue , pp 317- 

678 (papers presented during the International Working Meeting on Soil Micromorphology, 2001, Gent, 

Belgium) (2003) 

294


SPHEROIDAL WEATHERING OF DOLERITE IN SURINAME: 

EVIDENCE FROM PHYSICAL, CHEMICAL AND 

MINERALOGICAL DATA 

C. G. Algoe 1* , E. Van Ranst 2 , G. Stoops 3 

1* Anton de Kom Universiteit van Suriname, Faculteit der Technologische Wetenschappen, POB 9212, 

Paramaribo, Suriname, Tel: +597 465558 ext. 413, Fax: +597 495005, Email: c.algoe@uvs.edu 

2 Laboratorium voor Bodemkunde, Universiteit Gent, Krijgslaan 281, S8, B-9000 Gent, Belgium 

3 Laboratorium voor Mineralogie, Petrologie en Micropedologie, Universiteit Gent, Krijgslaan 281, S8 B-9000 

Gent, Belgium 


Suriname consists geologically for about 80 % of a Precambrian basement, the Guiana shield. 

At numerous places this shield is intersected by Permo-Triassic NS striking dolerite dike 

suites. In the regolith they appear as spheroidally weathered boulders with an “onion-skin” 

fabric. 

Four weathered boulders were collected in profiles near the locality Berg en Dal and 

shells of different weathering grades sub-sampled in the laboratory. These shell-samples were 

analysed using physical, chemical and mineralogical methods in order to characterize the 

spheroidal weathering process and the resulting weathering products. The chemical analyses 

comprise total elemental contents, oxalate and dithionite-citrate-bicarbonate extractions, 

cation exchange capacities and pH values. The mineralogical data is obtained from thin 

section studies, WDS microprobe analyses, X ray diffraction data, and scanning electron 

microscopy. 

The bulk densities show a vast decrease with increasing weathering grade. The total 

elemental data show a progressive and complete loss of the alkaline and earth alkaline 

elements in course of the weathering process. These data also allow the calculation of a 

number of weathering indices, used to define the behaviour of elements during the weathering 

process. The total elemental data and bulk densities are used to calculate the isovolumetric 

weathering in the boulders. Special attention is given to the behaviour of both free and 

amorphous Fe as revealed from the oxalate and dithionite-citrate-bicarbonate extractions. 

The unweathered parent material consists predominantly of lath-shaped plagioclases 

(andesite and labradorite), pyroxenes (augite and pigeonite), chlorites, opaque minerals 

(ilmenite and titanomagnetite), granophyric intergrowths of quartz, feldspars, apatite and 

ilmenite. In addition amphiboles and apatite occur in small amounts. All mineral data of the 

weathered samples point to an end system with residual weathering products consisting 

mainly of clay minerals (kaolinite and chlorite) and Fe- and Al-hydroxides (goethite and 

gibbsite). Weathering of minerals takes place abruptly, and although the original minerals are 

completely altered, their alteromorphs can still be recognised in the thin sections upto the 

latest weathering stages. 

The isovolumetric condition of spheroidal weathering and the mobility of Al and Ti in 

the weathering system are discussed as well as the in situ character of the boulders based on 

the sharp contrasts in data between weathered dolerite samples and the residual soil. Another 

point of discussion is the influence of magnetic minerals on the oxalate and DCB extractable 

components. 

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MICROMORPHOLOGICAL CHARACTERISTICS OF ANDISOLS 

IN WEST JAVA, INDONESIA 

Abstract 

Mahfud Arifin * , Rina Devnita 

Dept. of Soil Science, Faculty of Agriculture, Padjadjaran University, Bandung, Indonesia 

mahfud_arifins@yahoo.com 

Tel. ++62-22/779.63.16 Fax. ++62-22/779.63.16; ++62-22/779.72.00 

Micromorphological characteristics have been studied for six pedons of Andisols developed 

in volcanic materials in West java, Indonesia. The pedons represent deposits of different 

volcanoes (Mt.Tangkuban Perahu A and C, Mt. Patuha, Mt. Kendeng, Mt. Papandayan, Mt. 

Guntur), with different ages (Pleistocene, Holocene) and different types of volcanism 

(andesitic, basaltic), in three agroclimatic zones (A, B1, B2). Undisturbed soil samples for 

thin section preparation were taken from every identifiable horizon (49 samples in total). 

Observations were made with a magnifying lens, binocular stereomicroscope, polarization 

microscope, and scanning electron microscope. The results demonstrate that the study of 

micromorphological characteristics is very useful to identify pedogenetic processes in 

Andisols. 

INTRODUCTION 

Soil micromorphology is a method to study undisturbed soil samples using microscopic and 

submicroscopic techniques to identify soil components and establish their spatial, temporal, 

genetic and functional relationships [3, 13]. 

Historically, micromorphological investigations have mainly been used for soil 

genesis studies, but they also have wider applications, e.g. in soil physics, biology and 

chemistry [3]. Two basic principles of micropedology are the use of undisturbed (oriented) 

samples and the concept of functional research whereby all observations are directed towards 

reaching as an understanding of the function of soil components and the relationship between 

one another. 

Micropedology covers all microscopic analyses of undisturbed soil samples [14], 

including the study of soil thin sections, microchemical and microphysical methods, and 

submicroscopic techniques. The most advanced analysis is the study of the entire soil fabric 

(soil micromorphology) and its quantitative aspects (soil micromorphometry). 

Many soil micromorphology studies have been conducted and published, especially on 

Ultisols, Oxisols, Spodosols and Paleosols [3]. However, research on Andisols is still rare, 

especially in Indonesia. Therefore, there is only a few information concerning 

micromorphological features of Andisols in Indonesia, particularly the Andisols developing 

on different parent materials and in different agroclimatic zones. 

For this study, research has been done on the micromorphological characteristics of 

Andisols in six pedons in the tea plantation area of West Java, Indonesia. The studied soils 

represent six different volcanic eruptions, ages, and parent materials, in three agroclimatic 

zones [11]. 

296



Pedon CTR-A2 (Acrudoxic Durudan) represents eruption C (middle Holocene) of Mt. 

Tangkuban Perahu (Ciater District, andesitic, agroclimatic zone A), and pedon CTR-B4 

(Acrudoxic Thaptic Hydrudand) represents eruption A (early Holocene) of Mt. Tangkuban 

Perahu (Ciater District, andesitic, agroclimatic zone A), both located in Subang Regency. 

Pedon SNR-A2 (Acrudoxic Hydrudand) at Mt. Kendeng (Sinumbra District, Pleistocene, 

andesitic, agroclimatic zone B1), pedon SNR-B5 (Lithic Hapludand) at Mt. Patuha (Sinumbra 

District, Holocene, basaltic, B1), pedon SDP-A3 (Typic Hapludand) at Mt. Guntur Cs (Sedep 

District, Pleistocene, basaltic, agroclimatic zone B2), and pedon SDP-B5 (Hydric Thaptic 

Hapludand) at Mt. Papandayan (Sedep District, Holocene, basaltic, agroclimatic zone B2) are 

all located in Bandung Regency. 

Undisturbed soil samples for the preparation of soil thin sections were obtained for 

every identifiable horizon in all profiles. The total number of samples was 49. 

Preparation of the soil thin sections involved hardening of the samples by impregnation. 

Observations of the undisturbed samples were made with the naked eye, a magnifier lens, 

binocular stereomicroscope, polarization microscope and scanning electron microscope. The 

terminology and concepts of the Handbook for Soil Thin Section Description [3] were used, 

with a few modifications. 

Micromass Colour 


The colour of the micromass as observed in thin sections partly depends on thickness, light 

source properties and magnification. 

In this study, only small variations in colour were observed. Horizon A/Bw has a 

brown to dark brown colour. Horizon BC generally has a lighter colour compared to the other 

genetic horizons. Surface horizons and buried A horizons have the darkest colour. In 

general, the horizons of pedons CTR-A2, SNR-A2, SNR-B5 and SDP-A3 have a brown 

colour, except pedon SDP-A3, which was lighter. Pedon CTR-B4 and SDP-B5 have a dark 

brown colour. 

The micromass colour in the thin sections was generally more brownish than the field soil 

capacity colour. Rainfall, age and parent material appear to have no significant effect on 

micromass colour. However, in Ciater District pedon CTR-A2 generally has a lighter colour 

than CTR-B4, in Sinumbra District pedon SNR-A2 has a lighter colour than SNR-B5, and in 

Sedep District SDP-A3 is lighter than SDP-B5. This indicates that the older parent 

materials have a lighter colour than the younger parent materials. 

Microstructure 

Microstructure refers to the shape, size and arrangement of soil aggregates and pores, 

generally observed at rather low magnification. 

Pedality 

The complete results of observation of the microstructure are presented in Table 1. Some 

examples of soil microstructure features are presented in Figure 1. The microstructure of the 

Andisols ranges from granular to massive. The surface horizon generally has crumb and 

297


granular microstructures (Fig. 1.a and 1.b), whereas the subsurface horizon has a blocky to 

subangular blocky microstructure. 

The surface horizons (Ap) of soils developed in areas with high rainfall (e.g. Ciater) 

have a more strongly developed pedality (and darker colour) than those developed in 

relatively drier areas (Sinumbra and Sedep), which generally also have a lighter colour and 

tend to show rounded and subangular peds. This suggests a relationship between organic 

matter content and pedality. Besides, the granular peds in the Ap horizon of soils developing 

on older parent materials are generally larger and have a denser groundmass than the younger 

soils. Chemical analysis indicates that the Ap horizon has a high organic carbon content and 

also contain Al- and Fe-bearing organic complexes. Those materials are predicted to play a 

role in forming a stable granular microstructure. 

In all horizons, the size of the peds shows a rather wide range (0.02-11.00 mm). The degree 

of accommodation ranges from well accommodated to unaccommodated, and is generally 

partly accommodated (Fig. 1.f). 

Types of voids 

In surface horizons, compound packing voids are observed (Fig. 1.a and 1.b). The voids are 

equant to elongate, interconnected, occurring between granular, crumb and angular blocky 

peds, which are unaccommodated. Other void types that are recognized are planar voids, 

chambers and vughs (Fig. 1.a, 1.b, 1.f) 

Subsurface horizons, which show crumb, granular or angular blocky microstructures, 

with or without pores, generally have planar voids, or planar voids with compound packing 

voids (Fig. 1.f). In a subsurface horizon (A’’, Bw) developed on old parent material (e.g. 

pedon SNR-A2 and SDP-A3), planar voids, vughs, channels, chambers and vesicles are 

recognized. 

a 

c 

b 

d 

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e 

g 

Figure 1. Photomicrograph of thin section with plane polarized light. Hor. Ap, CTR-A2 (a); Hor. Ap, 

SNR-B5 (b); Hor B’wb, SDP-A3 (c); Hor. 2Ab SNR-A2 (d); Hor. 3Ab, CTR-A2 (e); Hor. Ap, SNR-A2 

(f); Hor. A’b2, SDP-A3 (g); Hor. Bw SDP-A3 (h) 

f 

h 

Planar voids in the surface horizon (Ap) generally developed along roots residues or 

microfauna remains. In the subsurface horizon, planar void mainly formed by development 

of cracks in dense groundmass material. 

Abundance of voids 

The abundance of voids in the thin sections was determined, expressed as percentage of the 

total area of the thin section [5]. The results show that surface horizons have a higher 

porosity than the subsurface horizons. Hence, the percentage of voids decreases with depth. 

This can be clearly seen in old pedons such as SNR-A2 and SDP-A3. This was predicted 

referring to processes of infilling of voids by illuvial material derived from the groundmass by 

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percolation of water, gravity, and biological activity, taking place during a long period. 

Therefore several pores have been closed by material derived from upper horizons. 

Related Distribution Patterns 

Horizons in Andisols have porphyric and enaulic c/f related distribution patterns, i.e. they are 

composed of coarse material embedded in finer material (porphyric) or they have a skeleton 

of larger fabric units with aggregates of fine material in the interstitial spaces (enaulic) [1,8]. 

In the latter, the aggregates do not completely fill the interstitial spaces, and the larger units 

support each other. 

Surface horizon generally have enaulic c/f related distribution patterns (Fig. 1.a and 

1.b), especially in Andisols developed on young parent materials. Andisols developed from 

old parent material have porphyric c/f related distribution patterns in their surface horizon. 

The granular or crumb structure in the surface horizon could be related to high biological 

activity (e.g. termites, ants), and the intensive growth of roots. The allophane content in the 

surface horizon is generally lower than in subsurface horizons due to the strong accumulation 

of organic matter in the surface horizon, preventing the formation of allophanes because of 

the formation of Al-humus complexes [9]. 

The subsurface horizons have porphyric c/f related distribution patterns. These 

horizons have a high total density, with porous and non porous parts. Pores in the porous parts 

can be filled with material derived from upper horizons. With time, they can develop into 

non-porous materials in this way. 

Pedons SNR-A2 and SDP-A3 have porphyric c/f related distribution patterns (Fig. 1.c 

and 1.d). Both pedons represents the older parent materials. The partly short range-order 

minerals have been weathered to crystalline minerals like halloysite, metahalloysite and 

gibbsite. The change in mineral composition was predicted to be accompanied by a change in 

c/f related distribution pattern from enaulic to porphyric. 

The subsurface horizons of pedon CTR-B4 still have enaulic c/f related distribution 

patterns, although the age of this pedon is older than that of CTR-A2, which shows porphyric 

c/f related distribution patterns. This indicates that the accumulation process in the subsurface 

horizons (pedon CTR-A2) was intensive due to the presence of impervious layers that prevent 

transportation of material to the lower horizons. 

Pedon/ Depth Shape Size Pedality Acc. Proportion 

Hor. (cm) 

(mm) 

(%) 

Pedon CTR-A2 

Ap 0-17 gr 0.042-0.2 s no 80 

ab 0.4-4.0 w pr 20 

Bw 17-31 gr 0.04-0.4 m-w no 45 

sab 0.4-1.6 w pr 55 

BC 31-43 ab-sab 1.6-2,8 w pr 30 

gr 0.4-0.8 w no 30 

gr 0.04-0.12 w no 40 

2Ab 43-60 gr < 0.08 w-m pr 20 

gr 0.4-0.8 w-m pr 40 

gr 1.6-2.4 w no 40 

2Bw 60-70 cr-gr 0.04-0.2 m-s pr 40 

ab 0.08-4.4 m-s pr 60 

2BC 70-94 mv - - - 90 

ab - m no 10 

300


3Ab 94-110 sab 0.4-0.8 m pr 40 

cr 0.04-1.2 w no 60 

3Bw 110-128 ab 4.8 s-m pr 80 

gr 0.08-0.4 s-m no 20 

Pedon CTR-B4 

Ap 0-15 gr 0.04-0.2 m no 60 

gr 0.2-0.4 m no 20 

gr 0.4-3.2 m no 20 

Bw 15-30 cr 0.04-11.0 m no 70 

ab 2.0-5.0 m no 30 

BC 30-38 mv - - - 100 

2Ab 38-52 cr 0.02-0.04 m no 80 

ab 0.4-1.0 m pr 20 

2BCb1 52-65 gr 0.02-0.2 m no 60 

ab 0.7-2.0 m pr 40 

2BCb2 65-90 ab 5.0 m pr 100 

2A’b1 90-105 ab 0.04-0.4 m pr 50 

ab 1.0-7.0 m pr 50 

2A’b2 105-120 ab 1.0-8.0 m pr 85 

gr 0.04-0.8 m no 15 

Pedon SNR-A2 

Ap 0-10 gr 2.0-3.0 m no 100 

Bw1 10-23 ab 2.0-5.0 s no 50 

sab 5.0-5.9 s no 50 

Bw2 23-40 ab 3.0-5.0 s gd 100 

Bw3 40-54 sab 1.0-10.0 s pr 70 

BC 54-73 sab 5.0-10.0 m pr 70 

2Ab 73-84 ab,sab 5.0-7.0 m pr 80 

2BCb 84-98 ab 2.0-7.0 m pr 100 

2A’b -120/130 ab 2.0-3.0 m pr 80 

2BC’b -142/148 sab,ab 1.0-2.5 m pr 100 

Pedon SNR-B5 

Ap 0-10 ab,sab 0.04-4.0 m pr 70;30 

Bw 10-19 ab,gr 0.04-3.6 m pr 70;30 

A’b 19-44 ab,gr 0.2-1.2 m pr 70;30 

Bcb 44-60 ab,sab 0.5-5.0 m pr 

Pedon SDP-A3 

Ap 0-14 ab 1.0-5.0 m pr 100 

A2 14-24 ab,gr 1.0-4.0 m no 50:50 

Bw 24-35 ab 0.05-5.0 m pr 60 

gr 0.12-0.24 m pr 40 

A’b1 35-46 ab 1.0-10.0 m gd 100 

A’b2 46-65 ab 0.1-5.0 m pr 100 

B’wb 65-81 ab 0.4-10.0 m gd 100 

A”b 81-95 ab 1.0-5.0 m pr 100 

B”wb 95-105 ab 0.4-2.8 m pr 100 

BCb 105-130 ab,mv - w pr 

Pedon SDP-B5 

301


Ap 0-11 sab 1.0-8.0 m pr 100 

Bw 11-30 gr,sab - m pr 25:75 

A’b 30-45 sab,gr - m pr 70:30 

B’wb 45-54 sab 0.2-2.4 m pr 70 

gr 0.08-2.4 m pr 30 

A”b1 54-72 sab - s pr 100 

A”b2 72-94 sab 0.2-1.0 m pr 70 

gr 0.02-0.04 m pr 30 

B”wb 94-115 sab 7.0-8.0 m pr 100 

BCb 115-135 sab 0.4-4.00 m pr 100 

A”’b 135-152 sab 0.4-2.4 s pr 100 

Table 1. Shape and size of aggregates, degree of pedality and accommodation of the studied profiles. 

ab; angular blocky;sab subangular blocky; gr granular; cr crumb; mv massive; w weak; m medium; s 

strong; pr part; gd good; no non 

Pedofeatures and weathering features 

The types of pedofeatures that have been recognized are textural, amorphous and 

cryptocrystalline, fabric and excrement pedofeatures [3,4]. Weathering of primary mineral 

grains is also considered in this chapter. Table 2 gives a detailed overview of the 

pedofeatures observed in every studied horizon. 

The features most commonly found in Andisols are the weathering of primary minerals 

and the illuviation and accumulation of material derived from upper horizons, as found by 

Goenadi and Tan [6, 7]. Illuvial material can be material derived from the groundmass, or 

fine organic material mixed with silt to very fine sand (Fig. 1.c and 1.d). In addition, humic 

substances quite often penetrate the groundmass. These pedofeatures are generally found in 

the site with young parent material and high rainfall (Ciater), or in the horizon directly 

underlying the buried A horizon (thaptic) (Fig. 1.e). 

The other features generally found were the strong alteration of primary mineral, e.g. 

minerals susceptible to physical and chemical weathering in A, B, and BC horizons. Physical 

weathering can be in the form of fragmentation. Chemical weathering can be recognized by 

the change of form or colour of the mineral grains. 

Mineral grains in pedons originated from old parent material generally have anhedral shapes 

(and low c/f2µ ratios), whereas grains in younger pedons usually have subhedral to euhedral 

shape (and higher c/f2µ ratios). Iron nodules are found in old pedon like SDP-A3 in Sedep 

(Fig. 1.g). The nodules were formed by residual accumulation of iron compounds, related to 

weathering of primary minerals. Gibbsite coatings (Fig. 2.a) are found in Acrudoxic 

Hapludand. 

Weak indications for clay illuviation are only recognized for the B’wb horizon in 

pedon SDP-A3, originated from old parent material, and in horizon 2BCb of pedon SNR-A2 

(Fig. 2.b). These horizons do not fulfill the prerequisite of an argillic horizon in Soil 

Taxonomy [12] due to the small total volume of illuvial clay (< 1 %) and the low degree of 

orientation within the clay coatings. Maeda et al [10] also reported a few coatings in 

Andisols. Mohr et al [11] proposed that Andisols often include a horizon with clay 

accumulation. 

302


Pedon/horizon Pedofeatures and weathering features (and plant remains) 

CTR-A2 

Ap Partly weathered primary minerals 

Bw Voids of root residue filled by granular groundmass material [??] 

Fragment of altered root, coloured brown-black at the edge 

BC Planar voids filled by isotropic clay mixed with very fine sand 

2 Ab Fragment of yellowish weathered rock 

2Bw - 

2BC Plagioclase covered by opaque material 

3Ab Planar void filled by a mixture of clay and very fine sand 

3Bw Planar voids filled by clay 

Root residue, with black soil material at the edge 

CTR-B4 

Ap Voids of root residue, brownish, 20 % 

Bw Voids of root residue, 15 % 

BC Planar voids filled by a mixture of clay and very fine sand 

Brownish red organic fragments, 10 % 

2Ab - 

2BCb1 Voids of root residue and organic fragments, 10 % 

2BCb2 Planar void filled by granular clay aggregates and very fine sand 

Fragment of reddish weathered rocks with volcanic glass 

2A’b1 Tuff with volcanic glass and yellowish brown clay minerals 

2A’b2 Voids filled by very fine sand 

2B’wb Voids filled by very fine sand and groundmass material 

SNR-A2 

Ap Voids of tea plant’s root residue, reddish brown wall 

Bw1 Voids filled by gibbsite 

Bw2 Partly altered root fragments 

Bw3 - 

BC Voids of rounded root residue filled by granular groundmass material 

2Ab Planar void filled by clay and gibbsite 

2BCb Planar void filled by clay 

Root fragments, 7 % [or phytoliths ??] non crystalline !! 

2A”B Void of weathered mineral residue 

Planar void filled by clay and gibbsite 

2BC’b Planar voids and vughs filled by granular groundmass material 

SNR-B5 

Ap Opaque root fragments 

Bw Opaque root fragments 

A’b Opaque root fragments 

BC’b Voids of root residue, partly filled with groundmass material 

Typic nodules 

SDP-A3 

Ap Opaque and reddish brown root fragments 

Voids of root residue, partly filled with granular groundmass material 

A2 Typic and nucleic nodules 

Root fragments [or phytoliths ??] non crystalline !! 

Bw Typic and nucleic nodules 

303


BC Planar voids filled by groundmass material and very fine sand 

A’b1 Hypocoating in the planar voids 

Typic nodules 

Planar voids filled by groundmass material and very fine sand 

A’b2 Typic nodules 

Voids of root residue, reddish brown wall, partly coated by groundmass 

material 

B’wb Typic nodules 

Voids of root residue (Chamber), filled with groundmass material 

Typic hypocoating in planar voids 


A”b Planar voids coated by groundmass material and very fine sand (Typic) 

[type ?] 

B”wb Typic coating in planar voids 

Planar voids filled by groundmass material 

BC”b Coating in planar voids (Typic) 


Typic nodules 

SDP-B5 

Ap Planar voids filled by groundmass material and very fine sand 

Bw - 

A’b Planar voids filled by groundmass material and very fine sand 

Voids of weathered root residue, rounded, reddish brown wall 

B’wb Planar voids and compound packing voids filled by groundmass 

material and very fine sand 

A”b1 Planar voids filled by groundmass material and very fine sand 

A”b2 - 

B”wb Chamber filled by micropeds 

BCb - 

A”’b Planar voids and vesicles!! filled by groundmass material and very fine 

sand [vesicles ?] 

Table 2. Pedofeatures of every identifiable horizon in the studied soils. 

304


A 

C 

e 

b 

d 

Fig.2 . Scanning electron microscope images (a and e) and thin section photographs. Gibbsite 

coating in hor. 2BCb, SNR-A2 (a); clay coating in hor. B’wb-SDP-A3, XPL (b); coatings of organic 

material in hor. B’wb, SDP-A3, PPL (c); pores with infilling in hor. 2BCb, SNR-A2, XPL (d); clay 

coating on sand grains, hor. Bw, SNR-B5 (e) 

305


CONCLUSION 

(1) Pedofeatures observed in thin sections are very useful to reveal pedogenetic processes. 

The pedon developed after the eruption of Mt. Guntur has clay coatings and nodules. The 

pedon developed at Mt. Kendeng has gibbsite coatings, and pedons developed at Mt. 

Papandayan and Mt. Tangkuban Perahu (eruption A and C) had coatings of organic material. 

(2) Micromorphological characteristics of Andisols developed from old parent material 

were different from those of soils developed from young parent material. The former have 

porphyric c/f related distribution patterns, low c/f2µ ratios, poor sorting, common infillings and 

coatings of voids, a few clay and gibbsite coatings, anhedral primary mineral grains, planar 

voids, a blocky to angular blocky microstructure, well-developed pedality and good 

accommodation. The soils on young parent materials have enaulic c/f related distribution 

patterns, high c/f2µ ratios, poor sorting, infillings composed of groundmass material, silt and 

organic material, subhedral to euhedral primary mineral grains, a granular microstructure, a 

crumb to blocky microstructure with medium pedality, partly accommodated peds and 

compound packing voids. 

REFERENCES 

[1] Brewer, R. “Fabric and Mineral Analysis Soils”, John Wiley & Sons, Inc., New York, (1964). 

[2] Brewer, R. “Fabric and Mineral Analysis Soils”, Robert E. Krieger Publ. Co., New York, (1976). 

[3] Bullock, P. L., Federoff, N., Jongerius, A., Stoops, G. and T. Tursina, “Handbook for Soil Thin Section 

Description”, Waine Research Publ, 152 p (1985). 

[4] Bullock, P. L. “The Role of Micromorphology in the Study of Quaternary Soil Process. Soil and Quaternary 

Landscape Evolution”, J. Boardman (ed), John Wiley & Sons Lt, (1985). 

[5] FitzPatrick, E. A. “Micromorphology of Soils”, Chapman and Hall, London, (1984). 

[6] Goenadi, D. H. and Tan, K. H. “Mineralogy and micromorphology of soils from volcanic tuffs in the humid 

tropics”, SSSAJR, 53(6):1907-1911 (1989). 

[7] Goenadi, D. H. and Tan, K. H. “Relationship of soil fabric and particle-size distribution in Davidson soil”, 

Soil Sci. 147:264-269 (1989). 

[8] Goenadi, D.H and Tan, K. H. “Micromorphology and x-ray microanalysis of an Ultisols in the tropic”, Indon. 

J. Trop. Agric, 1:12-16 (1989). 

[9] Maeda, T., H. Takenaka and B.P Warkentin. “Physical properties of allophane soils”, Advances Agronomy, 

29:229-264 (1977). 

[10] Mohr, E.J.C., F.A van Baren and I. van Schuylenborg. ”Tropical Soils, A Comprehensive Study of Their 

Genesis”, The Hague-Paris-Djakarta, (1972). 

[11] Oldeman, L. R. “An Agroclimatic Map of Java Central Research”, Institute of Agricultur, Bogor, (1975). 

[12] Soil Survey Staff. “Keys to Soil Taxonomy, SMSS, Technical Monograph No.19, Fifth Edition”, 

Pocahontas Press. Inc, Blacksburg. Virginia, (1992). 

[13] Stoops, G and A. Jongerius. “Proposal for micromorphological classification in soil materials, I. A 

classification of the related distribution of coarse and fine particles”, Geoderma, 13: 189-200 (1975). 

[14] Stoops, G and H. Eswaran. “Soil Micromorphology”, Van Nostrand Reinhold, New York (1986). 

306


MICROMORPHOLOGICAL FEATURES OF SOME SOILS IN THE 

AFRAM PLAINS (GHANA, WEST AFRICA) 

M.D. Mays 1 , W.R. Effland 2 , T. Adjei-Gyapong 3 , C.D. Dedzoe 3 and E. Boateng 4 * 

1 National Soil Survey Centre, USDA-NRCS, Lincoln NE; 2 USDA-NRCS, Washington, D.C.; 

3 CSIR-SRI, Kumasi (Ghana); 4 CSIR/SRI, Accra (Ghana) 

E-mail: soilri@ncs.com.gh, Tel: 233-21-778226, Fax: 233-21-778219 


An eight-member sampling team from Ghana’s Council for Scientific and Industrial Research 

(CSIR) / Soil Research Institute (SRI) and from the USDA-National Resources Conservation 

Service (NRCS) sampled soils in the Upper Afram Basin as part of a co-operative project that 

included providing training in modern soil survey methodologies. 

The field portion of the project included sampling six soil pedons that represent a 

variety of soil types for complete analyses. These soils are developed in Paleozoic fine- and 

coarse-grained Voltaian sandstone and shale. The objective is to relate clay and optical 

mineralogy findings to micromorphological properties of the studied soils. As in many 

tropical soils, they did not reflect strong pedofeatures, except for clay illuviation, which may 

be masked in thin sections by illuvial iron and manganese that coats peds and grains. The 

illuvial iron/ferri-argillans mask the cation exchange capacity of the soil and other clay 

expressions such as x-ray diffractions. It also fixes phosphorous and produces the red colour 

exhibited in these soils. 

X-ray diffraction analysis showed that quartz is the dominant mineral in the clay 

fraction. Faunal activity, e.g. by termites and earthworms, and vegetation differences are 

important soil developmental factors observed in thin sections. Also, iron and clay illuviation 

was dominant in soils on mature landscapes. Quartz grains in thin sections in these soils are 

highly weathered with rounded edges and striated marks in grains surfaces. These features 

are evidence of the long and continuous weathering that has taken place in these soils or 

parent materials over time. Remnants of termite and worm activity include vermiform features 

composed of kaolinitic clays that have been ingested and are plastered along the walls of 

channel. The soils in this study record a large variation in animal activities. There was a larger 

variety of activities in the surface layer of forested areas than in cultivated fields. However, 

termites were active in both forested and cultivated areas. 

REFERENCES 

[173] S.V. Adu, J. A. Mensah-Ansah. "Soils of the Afram Basin, Ashantiand Eastern Regions, Ghana", 

CSIR-Soil Research Institute, Memoir No. 12. Kwadaso-Kumasi, Ghana. 90pp, (1995). 

[174] D.A. Bates. Geology. P51-61. In J. Brian Wills (ed). "Agriculture and land use in Ghana", Oxford 

University Press, London, (1962). 

[175] R. Brewer. "Fabric and Mineral Analysis of Soils", John Wiley & Sons, Inc. New York. 304pp., (1964). 

[176] E.A. FitzPatrick. "Soil Microscopy and Micromorphology", John Wiley & Sons, Inc. New York. 

304pp., (1993). 

[177] Soil Survey Staff. "Keys to Soil Taxnomy", Ninth Edition. United States Department of Agriculture 

and Natural Resources Conservation Service. 332pp., (2003). 

[178] G. Stoops. "Guidelines for Analysis and Description of Soil and Regolith Thin Sections", Soil Science 

Society of America, Inc. Madison, WI, 184pp, (2003). 

307


WORKSHOP Theme: Soil Processes and analytical techniques 

Convenors: E. Van Ranst, G. Stoops, F. Mees, V. Marcelino 

CONCLUSIONS 

About 15 participants attended the session for this workshop theme. They were mainly 

alumni of the former “Soil Science” and “Soil Science and Eremology” programmes, in 

which more attention was given to the understanding of soil genesis and dynamics (e.g. using 

mineralogical and micromorphological methods) compared to the curriculum of the present 

“Physical Land Resources” programme. A majority of the participants is involved in teaching 

at university level, which implies that the total impact of the session will be important, due to 

the multiplication effect of dealing with teaching staff. 

The first part of the session was concentrated mainly on soil mineralogy. E. Van Ranst 

(UGent), chairing that part, illustrated the importance of physico-chemical and mineralogical 

studies of the clay fraction for understanding soil dynamics, followed by a presentation of an 

ongoing research project about authigenic mineral formation (F. Mees, UGent). Lectures by 

Fiantis et al. and Morras et al. illustrated the use of various techniques for the mineralogical 

study of soils. 

During the coffee break, attention was focussed on the presentation of posters by 

participants of this workshop theme session. 

The second part started with an introduction by G. Stoops (UGent), describing recent 

advances in soil micromorphology and the present research in this field within the 

Department, followed by more detailed discussions on the problem of comparing 

micromorphometric data obtained by different techniques (V. Marcelino, UGent) and on the 

application of X-ray tomography in soil micromorphology (F. Mees, UGent). Two alumni 

presented papers on their current research in Suriname and Indonesia, using combined 

mineralogical and micromorphological techniques to disentangle complex pedogenic 

processes. 

All presentations, during both parts of the session, were followed by a discussion with 

the audience. 

308


309

Closing Word 

CLOSING WORD 

Closing Address by Prof. E. Van Ranst, Chairman Steering Committee Physical Land 

Resources and Promotor of the Master Programme (UGent) 

310


Closing Address by Prof. E. Van Ranst, Chairman Steering 

Committee Physical Land Resources and Promotor of the Master 

Programme (UGent) 



Dear Alumni, 




On behalf of the Steering Committee and the Staff of our programme in PLR, I first want to 

congratulate all of you, alumni and staff who attended this 5 th refresher course, for your 

contributions and active participation in the discussions. I am proud to be able to announce 

that this refresher course was attended by 40 alumni coming from 22 countries spread over 

different continents. As I said already during my opening speech, our major objective was to 

come to an overall exchange of knowledge and information from alumni to staff and vice 

versa, as well as amongst alumni. I hope we have succeeded in this objective? I hope that all 

of you enjoyed the sessions, that you could establish cooperative linkages, upgrade your 

knowledge with the latest developments in the field of soil science and engineering geology, 

and that you were able to collect valuable information about the wide range of existing 

funding opportunities provided by VLIR or offered by other institutions in Belgium that are 

involved in development cooperation. 

I think that the information session we had on Monday afternoon on possibilities for cooperation, 

financial support, project planning, etc.. with presentations of VLIR, BTC, the 

Department of Research Affairs from the Ghent University and the Department for 

Development Cooperation of the Free University of Brussels was very informative to 

strengthen your academic cooperation in the near future or to help younger colleagues or 

scientists of your institute in their further training or career development. 

The flash presentations proved to be an ideal communication tool, inviting us to explore the 

differences and similarities in the problems you, the alumni, face while developing your 

scientific career. It stressed the importance of funding – through projects with professors from 

Ghent University and the Free university of Brussels - but it also highlighted opportunities for 

co-operation among the alumni themselves. 

The most important limitation experienced by the majority of the speakers is the lack of funds 

and consequently, there’s a high necessity for cooperation with other institutes through 

projects. The funds raised as such are necessary to buy basic equipment for laboratories or 

field experiments, or to buy data such as climatic records or satellite imagery. The 

collaboration with European universities also opens opportunities for knowledge exchange, 

through guest lectures or short trainings. The insight in current leading research topics is 

broadened as the alumni get access to e-papers. 

311


However, a project starts with writing a well-prepared project proposal, and this initial 

proposal writing is not as evident as it seems if there’s no access to basic computer 

infrastructure, internet services or e-subscriptions to journals that allow the alumni to keep 

pace with the latest developments in their field of expertise. 

Once the project finishes, often, there are no funds anymore that can be used to maintain, 

repair or order spare parts of the laboratory equipment acquired. This opened the discussion 

with respect to the frequent demand of alumni for more sophisticated instruments. In reality, 

they more urgently need good basic infrastructure that is maintained correctly. This 

maintenance not only requires funds, but also a good management with continuous 

supervision. 

All speakers are also willing to exchange MSc and PhD students. These foreign students bring 

along with them their knowledge of tools, theories, and new advances in soil science. On the 

other hand, several alumni highlighted the lack of interest in soil science shown by the local 

students. Often, these students don’t choose for soil science because they don’t have any idea 

of the potential future jobs. They also need to be convinced of the persisting (or even 

increasing) importance of soil science in our modern communities. 

Upon the demand for more « upgraded » local staff, the problem of brain-drain is raised, 

faced by many developing countries. However, there are also positive, encouraging 

statements. Facing all the problems, making it difficult (at might take several years) to get a 

project proposal launched, some of the speakers already successfully got involved in national 

and international projects. Cooperation among the alumni of different universities or research 

institutes within a country or within neighbouring countries, is often a way of getting access 

to papers, to data, or to specific laboratory instruments. 

Also our newsletter “PEDON” can play a major role in all this, as I mentioned already in the 

editorial of Pedon nr. 16 (2005). I wish to remind everyone of you that Pedon is not meant as 

a one-way channel of information from our centre towards alumni. Pedon also makes room 

for your contributions, reactions, call for research partners, important events in your research 

groups, as well as activities and projects organised in the frame of the soil science – and 

engineering geology – community in your country and, perhaps, by associations of alumni. 

In 1992, a local Alumni Association was set up in Malaysia. We have about 70 alumni from 

Malaysia, and they were one of the most prominent countries represented here during the 

seventies and eighties. At present, other nationalities surface in our international student 

community. Ethiopia is certainly taking the lead. In 1996, an association of Ethiopian alumni 

from Belgian universities was founded. Although this association groups alumni from 

different programs in Belgium, it does provide a channel through which our alumni can meet 

and (we hope) keep contact. Associations like these can facilitate networking and set up of 

research activities within and across borders. 

Please send us information to be published in PEDON! 

312


Before ending this speech, I once again would like to thank the VLIR for co-financing this 

event; the Ghent University for hosting this workshop, and especially the administrative staff 

of the secretariat of the PLR for the hard work done over the past weeks making the 

organization of this refresher course possible. 

Thanks, let’s keep in touch, and have a safe journey back home. 

313 

Prof. E. Van Ranst

Agenda 

Workshop for Alumni of the M.Sc. programmes in Soil Science, Eremology 

and Physical Land Resources 

Sunday September 3, 2006 : 

NEW WAVES IN PHYSICAL LAND RESOURCES 

3-9 September 2006 

AGENDA 

04.00–06.00 pm : Registration and reception of participants, Faculty of Bioscience 

Engineering, Coupure Links 653, 9000 Gent (FBE, UGent), Bldg. E 

Monday September 4, 2006 : 

Place: Faculty of Bioscience Engineering, Coupure Links 653, 9000 Gent (FBE, UGent), 

Bldg. E, room E009 

09.00-09.30 am : Registration 

09.30-10.00 am : Welcome of the participants by 

. course promoter(s) 

. Rector UGent 

. Director VLIR-UOS (K. Verbrugghen) 

10.00-11.30 am : Opening lectures by alumni 

. Prof. Dr. Mitiku Haile, Rector, Mekelle University College, 

Ethiopia 

. Prof. Dr. Tang Hua-Jun, Director General, National Institute of 

Agricultural Resources and Regional Planning, Chinese Academy 

of Agricultural Science (CAAS), China 

. Prof. Dr. Erpul Gunay, Ankara University, Turkey 

11.30-02.00 pm : Reception - Lunch 

02.00-05.30 pm : Informative session on possibilities for co-operation, financial support, 

project planning etc. 

. UGent, Dept. Research Affairs (Dr. D. De Craemer) 

. VUB, Dept. Devt. Cooperation (J. Couder) 

. BTC (C. Michiels) 

. VLIR (F. Vermeulen) 

. DGOS (D. Molderez, A. Van Malderghem) 

314

Agenda 

Tuesday September 5, 2006 : 

Place: FBE (UGent), Bldg. E, room E009 

09.00–11.00 am : Flash presentations by alumni on background, current work, needs, 

demands for co-operation 

11.00–11.30 am : Break 

11.30-12.30 am : Discussion 

02.00–04.00 pm : Flash presentations by alumni on background, current work, needs, 

demands for co-operation (cont’d) 

04.00-04.30 pm : Break 

04.30-05.30 pm : Discussion 

6.00 pm : reception at the town hall and guided city walk 

Wednesday September 6, 2006 : 

Full day excursion: 

meeting time and meeting place: 

7.30 am: Monasterium Poortackere, Oude Houtlei 56, 9000 Gent 

8.00 am: in front of the entrance hall of the building S8, De Sterre, Krijgslaan 281, 9000 

Gent 

Expected time of return: It is expected to leave from Brussels around 4.00 pm. 

Morning : Visit to the labs of ICP staff at the VUB (Brussels) 

Afternoon : Visit to the Royal Museum of Central Africa, Tervuren, dept. 

Teledetection 

Thursday September 7, 2006 : 

Visit to the labs of ICP-staff (UGent): 

meeting time: 15 minutes before start of each tour (08.45 am and 01.45 pm respectively) 

meeting place: entrance hall of the building concerned (S8, Sterre and Bldg. B, FBE 

respectively) 

Note: a bus will pick up participants at the Monasterium at 8.30 am, with destination the 

Sterre. A bus will take the participants at 12.00 am to the FBE for lunch and continuation of 

the visit there. 

315

Agenda 

place time nr. lab/dept. 

De Sterre, S8 09.00 – 12.00 

am 

(3 groups) 

FBE, bldg B 02.00 – 05.30 

pm 

(4 groups) 

FBE, bldg A By appointment 8 

9 

10 

Friday September 8, 2006 : 

Place: FBE (UGent), Bldg. E 

09.00 – 12.30 

am 

break: 10.30-11.00 am 

02.00 – 05.30 

pm 

break: 03.30-04.00 pm 

1 

2 

3 

4 

5 

6 

7 

Lab. Soil Science 

Lab. Applied Geology & Hydrogeology 

Center for Remote Sensing 

Lab. Applied Physical Chemistry 

Lab. Analytical Chemistry & Applied Ecochemistry 

Lab. Soil Physics 

Lab. Soil Fertility & Data Processing 

Lab. Hydrology & Water Management 

Dept. Applied Ecologie & Environmental Biology 

Dept. Applied Mathematics, Biometry & Process 

Regulation 

: Parallel theme-workshops based on papers and posters: 

� Theme A : Soil and groundwater pollution and 

remediation 

� Theme C : Land evaluation and land degradation 

: Parallel theme-workshops based on papers and posters : 

� Theme B : Integrated soil fertility management 

� Theme D : Soil survey and soil inventory techniques 

� Theme E : Soil processes and analytical techniques 

7.30 pm : Workshop Dinner at Monasterium Poortackere, Oude Houtlei 56 

Saturday September 9, 2006 : 

Place: FBE (UGent), Bldg. E, room E010 

09.00 - 10.00 

am 

10.00 – 10.30 

am 

10.30 – 11.30 

am 

: 

: 

: 

Time for making reports of the workshops 

Coffee break 

Reporting on theme workshops, conclusions 

11.30 am : Closing of the meeting 

316 

Room 

E010 

E009 

Room 

E009 

E010 

E015

Agenda 

317

List of Participants 

LIST OF PARTICIPANTS 

Dr. Héctor Morrás 

Instituto Nacional de Tecnolgia Agropecuaria (INTA), Centro de Investigación de Recursos 

Naturales (CIRn) - Instituto de Suelos 

Las Cabañas y Los Reseros, 1712 Castelar, Argentina 

tel.: 54-1146211448 fax: 54-114811688 e-mail: hmorras@cirn.inta.gov.ar 

Promotion: 1972, Soil Science 

Ms. Katherine Verbeek 

Goedingenstraat 20, 9051 Afsnee, Belgium 

tel.: 0473/522513 fax: e-mail: kverbeek@skynet.be 


Prof. Boon Goh Tee 

University of Manitoba, Dept. Of Soil Science 

R3T 2NZ Winnipeg, Canada 

tel.: 204-4746046 fax: 204-4747642 e-mail: gohtb@ms.umanitoba.ca 


Dr. Youqi Chen 

National Institute of Natural Resources and Soil Science, CAAS, 

12 Zhong Guan Cun South Avenue, 100081 Beijing, China 

tel.: 0086-10-68919638 fax: 0086-10-68976016 

e-mail: 

Promotion: 

Dr. Jin Ke 

Soil and Fertilizers Institute, 

Baishiqiao 30, 100081 Beijing, China 

tel.: 0086-10-68918672 fax: e-mail: ke-jin@hotmail.com 

Promotion: 2002? Physical Land Resources 

Prof. Dr. Tang Huajun 

National Institute of Natural Resources and Soil Science, CAAS, 

12 Zhong Guan South Ave., 100081 Beijing, China 

tel.: 86-10-68919638 fax: 86-10-68976016 

e-mail: 


Prof. Dr., Dean Luhembwe Ngongo 

University of Lubumbashi, 

825 Lubumbashi, D.R. Congo 

tel.: 243-997027140 fax: e-mail: ngongoluhembwe@unilu.ac.cd 


318


Prof. Jorge Valarezo 

Universidad Nacional de Loja-Ecuador, 

Ciudad Universitaria, La Argelia, 1101 Loja, Ecuador 

tel.: 593-72546671 fax: 593-72545054 e-mail: jivg1@yahoo.es 


Ing. M.Sc. Carlos Valarezo 

Universidad Nacional de Loja-Ecuador, 

Ciudad Universitaria "Guillermo Falconi" - La Argelia, 1101 Loja, Ecuador 

tel.: 93-72545054 fax: 593-72584802 e-mail: cvalarezo@softhome.net 


Dr. Ahmed Taalab 

National Research Centre, 

Tahrrer St., 12622 Dokki, Cairo, Egypt 

tel.: 123991830 fax: 2023371362 e-mail: astaalab@hotmail.com 

Promotion: 

Prof. Dr. Mohamed El-Badawi 

National Research Centre, Soil Dept. 

El-Bohouse St., 123 Dokki, Cairo, Egypt 

tel.: 20123707177 fax: 20123370931 e-mail: badawi2712@yahoo.com 

Promotion: 1986, Ph.D. Soil Science 

Dr. Ageeb Gamil Waheeb 

National Research Centre, 

Al Bohos St., 12622 Dokki, Cairo, Egypt 

tel.: 202-0106833629 fax: 202-3370931 e-mail: gamilageeb@yahoo.com 


Prof. Dr., President Mitiku Haile 

Mekelle University, 

P.O. Box 231, 231 Mekelle, Ethiopia 

tel.: 251-344402264 fax: 251-344409304 e-mail: gualmitiku@yahoo.com 


Drs. Meklit Tariku 

Ugent, Dept. Soil Mant. & Soil Care 

Coupure Links 653, B 9000 Gent, Belgium 

tel.: fax: e-mail: Meklit.TarikuChernet@UGent.be 

Promotion: 2004, Physical Land Resources 

Mr. Enoch Boateng 

CSIR-Soil Research Institute, 

P.O. Box 1132, Accra, Ghana 

tel.: 233-244732410 fax: 233-21778219 e-mail: soilri@ncs.com.gh 


319


Mr. Ebenezer Abuaku 

University of Cape Coast, Dept. of Soil Science, School of Agriculture 

23342 Cape Coast, Ghana 

tel.: 233-244736051 fax: 233-21-774313 e-mail: ebentje@yahoo.co.uk 


Prof. Dr. Arifin Mahfud 

Padjadjaran University, Faculty of Agriculture, Dept. of Soil Science 

Jl. Raya Sumedang km 21 Jatinangor, 46000 Bandung, Indonesia 

tel.: 062-22-7797200 fax: 062-22-7796316 e-mail: mahfud_arifins@yahoo.com 

Promotion: 

ir. M.Sc. Rina Devnita 

Padjadjaran University, Faculty of Agriculture, Dept. of Soil Science 

Jl. Raya Sumedang km 21 Jatinangor, 46000 Bandung, Indonesia 

tel.: 062-22-7797200 fax: e-mail: rinabursi@yahoo.com 


Dr. Dian Fiantis 

University of Andalas, Dept. Of Soil Science, Faculty of Agriculture 

Kampus Unand Limau Manis, 25163 Padang, Indonesia 

tel.: 62-75128136 fax: 62-75172702 e-mail: dianfiantis@yahoo.com 


Dr. A. Arivin Rivaie 

Indonesian Centre for Estate Crops Research & Development, 

Jl. Tentara Pelajar n° 1, 16111 Bogor, Indonesia 

tel.: 62-251313083 fax: 62-251336194 e-mail: arivinrivaie@yahoo.com 

Promotion: 1998, Soil Science and Eremology 

Dr. Mugai Njue 

Jomo Kenyatta University of Agriculture and Technology, Horticulture Department 

P.O. Box 62000, Nairobi, Kenya 

tel.: 722-337605 fax: e-mail: nmugai@yahoo.com 


Dr. Philip Wandahwa 

Egerton University, Dept. Of Soil Science 

P.O. Box 536, Njoro, Kenya 

tel.: 254-733269460 fax: 254-5162527 e-mail: wandahwa2002@yahoo.com 


Mr. Peter Njoroge Kamande 

University of Nairobi, 

P.O. Box 29053, Nairobi, Kenya 

tel.: 254-726378491 fax: e-mail: pnkamande2002@yahoo.com 


320


Prof. Bin Jusop Shamshuddin 

Universiti Putra Malaysia, Department of Land Management, Faculty of Agriculture 

43400 Serdang, Selangor, Malaysia 

tel.: 603-89466985 fax: 603-89434419 e-mail: samsudin@agri.upm.edu.my 


Dr. Abdul Razzaq 

University of Agriculture, Dept. of Soil Science 

Faisalabad, Pakistan 

tel.: fax: e-mail: 


Dr. Renato Boniao 

MSU-NAAWAN, 

Naawan, Misamis Oriental, 9023 Naawan, Philippines 

tel.: H/P # 063 63 9164958669 fax: e-mail: natsupm@yahoo.com 


Prof. Rosa Poch 

Universitat de Lleida, Departament de Medi Ambient i Ciències del Sòl 

Av. Rovira Roure 191, 25198 Lleida, Spain 

tel.: 34973702621 fax: 34973702613 e-mail: rosa.poch@macs.udl.es 


Drs. Udayakantha Vitharana 

Ugent, Dept. Soil Mant. & Soil Care 

Coupure Links 653, B-9000 Gent, Belgium 

tel.: fax: e-mail: U.Vitharana@UGent.be 


M.Sc. Chandra G. Algoe 

Anton de Kom Universiteit van Suriname, Faculteit der Technologische Wetenschappen 

Universiteitscomplex, Leysweg, POB 9212, Paramaribo, Suriname 

tel.: 465558 ext. 413 fax: 495005 e-mail: c.algoe@uvs.edu 


Dr. Somjate Pratummintra 

Department of Agriculture, 

Chatuchak, 10900 Bangkok, Thailand 

tel.: 66-2-5790574 fax: 66-2-9405472 e-mail: spratummin@yahoo.com 


Dr. Gunay Erpul 

Ankara University, Faculty of Agriculture, Soil Science Department 

06110 Ankara, Turkey 

tel.: 90-312/5961796 fax: 90-312/5171917 e-mail: Gunay.Erpul@agri.anakara.edu.tr 

Promotion: 1996, Eremology 

321


Dr. Hasan Öztürk 

Ankara University, Faculty of Agriculture, Dept. of Soil Science 

06110 Diskapi, Ankara, Turkey 

tel.: 90-312-5961757 fax: 90-312-3178465 e-mail: hozturk@agri.ankara.edu.tr 

Promotion: 1997, Eremology 

Dr. Crammer Kayuki Kaizzi 

Kawanda Agricultural Research Institute (KARI), 

P.O. Box 7065, Kampala, Uganda 

tel.: 256-41567649696 fax: 256-41567649 e-mail: kckaizzi@hotmail.com 


M.Sc. Tran Thi Le Ha 

Hanoi Agricultural University, Faculty of Land and Environment, Department of Soil Science 

22A Duong S., Trau Quy, Gia Lam, 10700 Hanoi, Vietnam 

tel.: 84-912554602 fax: 84-48276554 e-mail: faithanoi@yahoo.com 


Mr. Dai Trung Nguyen 

Research Institute of Geology and Mineral Resources, Soil and Landuse Dvision 

Nguyen Trai Road, km 9 + 200 Chien Thang Street, Thanh Xuan, 0084 Hanoi, Vietnam 

tel.: 84-4/8543107 fax: 84-4/8542125 e-mail: trung_nd@yahoo.com 


Sr. Lecturer, Director Khoa Le Van 

Can Tho University, 

3/2 Street, Ninh Kieu District, Cantho City, Vietnam 

tel.: 84-71-832971 fax: 84-71-838474 e-mail: LVKhoa@ctu.edu.vn 

Promotion: 2002, Ph.D. 

322

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