Grain Legumes and Green Manures for Soil Fertility in ... - cimmyt

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Seed collection Seed collection was considered an important entry point for farmer involvement, and would enhance farmers' capacity to identify the legumes. No spe cific assignment was given to individual farmers. All volunteers made collections for more than one species, taking into consideration the spatial distri bu tion, time differences in reaching maturity and the differences in growth patterns among the differ ent species. Results Species diversity and abundance Thirty-three indigenous herbaceous legume species, mainly of the genera Crotalaria, Indigofera and Tephrosia, were identified among the three agrozones. Using the Gwezu smell technique, participating farmers and field assistants were able, not only to identify the legumes, but also to collect seed. The highest number of 28 legume species (Table 1) was recorded in Chinyika resettlement area. Ten of the total of 33 species were only present in Chinyika and not in the other two Communal Areas, while a further 10 species were commonly found in all areas. There was a critical lack of information on indigenous names for the diverse legumes identified. Farmers attributed this to fact that these species were generally not rated as problem weeds, neither were they used as a source of food at household level. They were therefore unlikely to be given specific names because of their little economic importance. Seed collection by farmers was feasible for all species except Alysicarpus ovalifolius. Because of a severe drought that started mid-way through the growing season, the determination of species abundance under cropped areas was rendered impossible. Weeds failed to germinate after the first weeding due to lack of moisture. Results on legumes species abundance were therefore only available from fallowed areas (Scenario II). Rothia hirsuta was the most dominant species in Chinyika where it constituted 71% of total legume biomass, while Indigofera astragalina was predominant in Chikwaka contributing 47% (Figure la and b). Crotalaria pisicarpa, predominated in semi-arid Zimuto where it contributed 39% to the total legume biomass, followed by R. hirsuta with 32% (Figure lc). .. Apart from R. hirsuta and I. astragalina which featured prominently across all agro-regions, there were significant differences in the abundance of species from one region to another. For instance, Crotalaria cylindrostachys only featured prominently in Chinyika while the most significant amounts of Zornia glochidiata biomass were measured in Zimuto (Figure 1). At Mr Zindoma's additional field site 70 Table 1. Species of indigenous herbaceous legumes identified to grow as weeds on smallholder farms in three agro·ecological regions in Zimbabwe legume species Agro·ecological region (NR) and site NR II: NR III: NR IV: Chikwaka Chinyika Zimuto Alysicarpus ovalifolius NI I NI Eflosema ellipticum NI I NI Crotalaria cylindrostachys I I I C. glauca NI I NI C. laburnifolia I NI I C. microcarpa I I I C. ochreleuca I I NI C. pisicarpa NI NI I C. rhodesiae I NI NI C. sphaerocarpa I NI Chamaecrista absus I I C. mimosoides I I Indigofera antunesiana NI NI I. astragalina I I I. brachynema NI NI I. demisa I NI I. fla vicans NI I I. nummularifolia NI NI I. praticola I NI I. vicioides I NI I. wildiana I NI NI Macrotyloma daltonii NI I I Neonotonia wightii I I I Rothia hirsuta I I I Stylosanthses fruticosa NI I NI Tephrosia acaciifolia NI I NI T. longipes NI I I T. lurida NI I NI T. purpurea NI I NI T. radicans I I I T. reptans I I NI Vigna vexillata NI NI I Zornia glochidiata I I I Total number of species 18 28 15 identified I - identified; NI - not identified in the area; NR II - 750 mm annual rainfall; NR III - 650·750 mm; NR IV - 450·650 mm (outside the regular sampling domain), there was a dense natural stand of legumes dominated by C. cylindrostachys with legumes contributed up to 88% of the above ground biomass (Figure '2), suggesting populations of the existing species are highly dynamic within a single growing season depending on soil management. No observable patterns in species distribution across catenary pOSitions were apparent in all areas during transect walks. The only notable exception was the growth and abundance of Vigna vexillata and Zornia glochidiata in bottomland positions (seasoIlally waterlogged or dambo fields) where the rest of the species were excluded. While the former was only restricted to dambo fields, the latter also occurred on topland and mid-slope positions down the catena. Grain Legumes and Green Manures for Soil Fertility in Southern Africa
a) Chikwaka b) Chinyika !21 C. absus [!] C. cylindrostachys • C. microcarpa 01. astragalina [j I. demisa 12:11. praticola .1. wildiana 47% BZl R. hirsuta tSI T. radicans Il§I Z. glochidiata i] C. cylindrostachys • C. microcarpa lID C. mimosoides 3% GI E. ellipticum 01. astragalina 2% 1(9/. praticola 71% 0% lID I. vicioides 1151 R. hirsuta !lim Z. glochidiata c) Zimuto range, for Zimbabwean soils, in Chikwaka and Zimuto. Overall, legumes contributed a maximum 12% of the total biomass harvested under high relative rainfall conditions (average 800 mm y r· l ) in Chikwaka, and as low as 3% in semi-arid Zimuto (Figure 3). The total biomass productivity was highest in Chinyika Resettlement Area, with slightly over 3 t ha- 1 , while Zimuto had no more than 0.75 t ha- 1 . Plant productivity was evidently reduced by drought in the second half of the season. N, P and K contents of identified species There were high variations in the tissue N, P and K concentrations of the legumes across the three study areas. About 12 out of the 35 sample entries across sites had more than 2% N (Table 3). In general there were more entries with high tissue N concentration from the semi-arid area than from the other two regions. Surprisingly high total N values of 5.02 and 5.88% were measured for C. inbul'izijolin and T. pUrpllrl!n, respectively, both of which were sampled in Zimuto. The number of samples with relatively high concentrations of P and K was generally high in Chinyika. t;] C. cylindrostachys o C. microcarpa Discussion !ill C. mimosoides The Gwezu Smell Technique for identification of legumes by farmers 13 C. pisicarpa 39% [] I. astragalina Participatory research is often constrained by lack of a common tool for as 32% D I. flavicans sessing or evaluating technologies. In &3 M. daltonii several instances, there is a technical language barrier between farmers and re ~R. hirsuta !Ill V. vexillata searchers. The Gwezu Smell Technique IIJ!l Z. glochidiata provides an identification tool that can be shared by researchers and farmers. The technique is easy and accessible to all Figure 1. The relative abundance of legume species, expressed as %of total legume farmers, and could the refore provide an biomass per unit area, identified in communal areas falling under different agro· opportunity for them to distinguish and ecoregions in Zimbabwe utilize legumes in their own environments. It could be combined with other Productivity of the legumes on abandoned infertile soils nodulation and nodule colour development used in assessment tools such as physical inspections for Most of the identified species were adapted to much the field for legume N 2-fixa tion appra!sals . There is, depleted coarse sandy soils with organic C averag however, a research challenge to identify the chemi ing less than 0.4% and mean available (Olsen) P lev cal substance responsible for giving this characteris els below 3 ppm (Table 2). About 89% of all the soils tic smell. sampled had less than 10% clay. The pH was slightly acidic in Chinyika but in the strongly acidic Grain Legumes and Green Manures for Soil Fertility in Southern Africa 71
Page 2 and 3:
Grain Legumes and Green Manures for
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Acknowledgments • The Leopard Roc
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Evall!ating mucuna green manure tec
Page 9:
INTRODUCTION AND CONFERENCE OBJECTI
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Table 1. Paradigm shifts underlying
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100 90 80 - - 0 - - Uptake by ihe m
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- 6 ~ 9 8 7 0- 5 CḎ ns 4 0::: 3
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Table 3. Millet grain and total dry
Page 20 and 21:
Dvorak KA 1996. Adoption potential
Page 23 and 24:
LEGUMES FOR SOIL FERTILITY IN SOUTH
Page 25 and 26:
to the system in such a way that th
Page 27: Muetzelfeldt, R.1. 1995. A framewor
Page 30 and 31: ing capacity. Legumes offer other b
Page 32 and 33: people/km2), land holdings are smal
Page 34 and 35: ments. It would help researchers to
Page 36 and 37: Own livestock Gununo farmers for th
Page 39: Questions and Answers ~ey Papers To
Page 42 and 43: Historical Perspective on Soyabean
Page 44 and 45: ganic amendment for resource-poor f
Page 46 and 47: MPhil. Thesis. University of Zimbab
Page 48 and 49: deal of research work has been bias
Page 50 and 51: 1600 '7 ns 1400 ~ 1200 Cl ~ 1000 "C
Page 52 and 53: Arbuscular mycorrhizal fungi (AMF)
Page 54 and 55: Boswell EP, Koide RT, Shumway DL, A
Page 56 and 57: Materials and Methods The trial was
Page 58 and 59: 0.9 0.8 ~ 0.7 Rec '-' 0.6 Vl ::9 0.
Page 60 and 61: Series no 5. Soil Science SOciety o
Page 62 and 63: Materials and Methods Persistence o
Page 64 and 65: content resulted in increased rhizo
Page 66 and 67: (Mugwiia and Murwira, 1997). Howeve
Page 68 and 69: Table 2. Average maize yield estima
Page 70 and 71: implied that most fanners prefer to
Page 73 and 74: ] Questions and Answers Rhizobium,
Page 75 and 76: ADDING A NEW DIMENSION TO THE IMPRO
Page 77: Materials and Methods The study use
Page 81 and 82: Table 3. N, P and Kconcentrations (
Page 83 and 84: Abstract SCREENING OF SHORT DURATIO
Page 85 and 86: Table 2. Characteristics of short d
Page 87 and 88: RISK DIVERSIFICATION OPPORTUNITIES
Page 89 and 90: management technologies with differ
Page 91 and 92: Table 3. Expected annual returns (Z
Page 93: Table 6. Risk diversification indic
Page 96 and 97: een renewed interest in green manur
Page 98 and 99: unfertilised maize crop of over 200
Page 101 and 102: Questions and Answers Screening of
Page 103 and 104: GREEN MANURE AND FOOD LEGUMES RESEA
Page 105 and 106: 7000 6000 ';' €.. 5000 .~MzSole :
Page 107 and 108: Table 5. Maize grain yield (kg ha")
Page 109: Phiri, A.D.K. 1999. Effects of Sesb
Page 112 and 113: amount of roots with sl:nnhemp. It
Page 114 and 115: It was proved that a mixed farming
Page 116 and 117: Table 3. Above·ground biomass (t/h
Page 118 and 119: and horticulture in Zimbabwe: Case
Page 121 and 122: GRAIN LEGUMES AND GREEN MANURES IN
Page 123 and 124: Results Table 1. Adaptation of gree
Page 125 and 126: Four rates of fertilizer N were app
Page 127 and 128: THE ROLE OF COWPEA (VIGNA UNGUICULA
Page 129 and 130:
Table 1. Non-legume cropping patter
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Table 9. Common pests on cowpeas as
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few of the farmers interviewed acqu
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Murwira, H.K., M.J. Swift and P.G.H
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Materials and Methods On farm exper
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18000 1600) 14000 a) Zambia 12000 m
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EFFECT OF DIFFERENT GREEN MANURE LE
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.. ~ Table 2. The effect of time o
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Chivinge, O.A., E. Kasembe, and I.K
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times with regionally specific adap
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ter content at 180 cm was still wel
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to amount of biomass, quality of bi
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with the natural fallow, which did
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and K to maize as an equivalent amo
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forts to understand the mechanisms
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gen recovery rates in relation to p
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The first steps to improve soil fer
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Questions and Answers .Identificat
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MUCUNA - MAIZE ROTATIONS AND SHORT
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Table 3. Percent nitrogen (% N) con
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~e decomposition of legume residues
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Table 3. Effect of forage legumes o
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available nutrients and vice versa,
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Conclusion and Recommendation Mucun
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Specific objectives were to: • Te
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'"~ v '" ~ ~ 1400000 1200000 100000
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EFFECT OF SURFACE APPLICATION AND I
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it 4 a···· · ... - :.!! e.....
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PERFORMANCE OF GREEN MANURES AND GR
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Mungwi soil, cowpea and soyabean pr
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Among BNF systems, symbiotic system
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3500 .f"'3000 ca ,c2500 CI "" - 200
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above-ground biomass was not transl
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3000 "0 ]i >. ,5 ~ C> 800 600 400 2
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Most interventions involving green
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~ ~~----.-~r-~-------------r~~ Aoo
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stover N, followed by after pigeon
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tems in Malawi and Zimbabwe. Procee
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1965). The tailings and AgLi were a
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The significant soybean yield could
Page 218 and 219:
twice the yield is necessary. We ha
Page 220 and 221:
Table 1. Maize and Grain Legumes Pr
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Recommendations and Conclusion In v
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performance of private sector compa
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the investment costs incurred. The
Page 228 and 229:
Results and Planning Workshop. Soil
Page 231 and 232:
A SOCIO-ECONOMIC ANALYSIS OF LEGUME
Page 233 and 234:
Table 1. Gross margins from the dif
Page 235 and 236:
Abstract LINKING TECHNOLOGY DEVELOP
Page 237 and 238:
3. If households are linked to prod
Page 239 and 240:
Table 9. Average Table 8. Pigeonpea
Page 241 and 242:
ance of sorghum-pigeonpea intercrop
Page 243:
Mligo, J.K., 1995. Pigeonpea breedi
Page 246 and 247:
To Charles Nhemachena, et al. Q: 1)
Page 248 and 249:
• Assessment of the potential ben
Page 250 and 251:
few studies characterized the house
Page 252 and 253:
• Conduct more research to measur
Page 254:
Socio-Economics, Policy and Technol
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