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TABLE OF CONTENTS
LIST OF TABLES ...................................................................................................................... vi
LIST OF FIGURES..................................................................................................................... vi
PREFACE .................................................................................................................................. vii
SUMMARY .............................................................................................................................. viii
RESUME.......................................................................................................................................x
1 INTRODUCTION......................................................................................................................1
1.1 Background and justification...............................................................................................1
1.2 Objectives of the study ........................................................................................................1
1.2.1 General objective ..........................................................................................................1
1.2.2 Specific objectives ........................................................................................................1
1.3 THE RESEARCH AREA....................................................................................................3
1.3.1 Characteristics of the physical environment .................................................................3
1.3.2 Socio-economic characteristics.....................................................................................6
2 FARMING SYSTEMS AND PRACTICES ..............................................................................7
2.1 Introduction .........................................................................................................................7
2.2 Methodology........................................................................................................................7
2.2.1 Site selection .................................................................................................................7
2.2.2 Participatory approach for farming system surveys......................................................8
2.2.3 Exploratory survey........................................................................................................8
2.2.4 Measurement of the size, crop density and yield of agricultural fields.........................9
2.2.5 Farmers’ priority setting ...............................................................................................9
2.2.6 Farmers’ strategies for soil fertility management .........................................................9
2.2.7 Household labour study ..............................................................................................10
2.3 Results and discussions .....................................................................................................10
2.3.1 Components of farms in the forest zone .....................................................................10
2.3.2 Socio-economic characteristics...................................................................................10
2.3.3 Cropping systems........................................................................................................13
2.3.4 Animal system ............................................................................................................21
2.3.5 Farmers' agricultural production priorities..................................................................23
2.3.6 Agricultural priority production constraints................................................................25
3 ASPECTS OF SOIL DEGRADATION UNDER VARIOUS LAND USE SYSTEMS..........28
3.1 Introduction .......................................................................................................................28
3.2 Methodology......................................................................................................................29
3.2.1 Site selection ...............................................................................................................29
3.2.2 Soil description and sampling.....................................................................................29
3.2.3 Laboratory soil analyses..............................................................................................30
3.3 Results and discussion.......................................................................................................30
3.3.1 Food crop fields and soil property changes.................................................................30
3.3.2 Fallow age and soil regeneration ................................................................................35
3.3.3 Perennial crops and soil degradation ..........................................................................41
3.3.4 Main causes of soil degradation and crop field abandonment in shifting cultivation
systems of the forest zone. ...................................................................................................42
4 TRENDS IN FIELD EXPANSION AND SOIL DEGRADATION, IN RELATION TO CROP
YIELD AND POPULATION PRESSURE ................................................................................46
4.1 Introduction .......................................................................................................................46
4.2 Methodology......................................................................................................................46
4.3 Results and discussions .....................................................................................................46
4.3.1Trends in agricultural field expansion .........................................................................46
4.3.2 Relationship between soil degradation and crop yield................................................48
4.3.3 Soil degradation and agricultural field expansion.......................................................49
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