A review of leguminous fertility-building crops, with particular ...

CONTENTS
EXECUTIVE SUMMARY................................................................................................................................. 1
1. INTRODUCTION................................................................................................................................... 14
1.1. WHAT ARE ‘FERTILITY-BUILDING CROPS’?............................................................................................ 14
1.2. ROLE IN ROTATIONS .............................................................................................................................. 14
1.3. WHAT IS ‘FERTILITY’?........................................................................................................................... 15
1.4. NUTRIENT SUPPLY................................................................................................................................. 16
1.5. ORGANIC MATTER ................................................................................................................................. 18
1.6. OBJECTIVES OF REVIEW......................................................................................................................... 19
1.7. DEFINITION OF TERMS ........................................................................................................................... 19
1.8. KEY ISSUES............................................................................................................................................ 20
2. FERTILITY-BUILDING CROPS IN ROTATIONS........................................................................... 21
2.1. INTRODUCTION...................................................................................................................................... 21
2.2. DISEASE IMPLICATIONS OF FERTILITY-BUILDING CROPS........................................................................ 28
2.3. THE INTERACTION OF FERTILITY-BUILDING CROPS AND INVERTEBRATE PESTS...................................... 31
2.4. INTERACTIONS BETWEEN PESTS AND DISEASES ..................................................................................... 40
2.5. CONCLUSIONS ....................................................................................................................................... 44
3. HOW MUCH N IS CAPTURED? ......................................................................................................... 45
3.1. FIXATION POTENTIAL OF DIFFERENT CROPS........................................................................................... 45
3.2. FACTORS AFFECTING N ACCUMULATION............................................................................................... 69
3.3. CONCLUSIONS ....................................................................................................................................... 90
4. THE INFLUENCE OF MANAGEMENT............................................................................................. 92
4.1. EFFECTS OF CUTTING AND MULCHING ON N CAPTURE AND LOSS .......................................................... 92
4.2. EFFECTS OF FORAGE OR GRAIN HARVEST ON N CAPTURE AND LOSS...................................................... 95
4.3. EFFECTS OF GRAZING ON N CAPTURE AND LOSS.................................................................................... 98
4.4. INTERACTIONS WITH MANURES AND COMPOSTS .................................................................................. 101
4.5. EFFECTS OF SOIL MANAGEMENT AND CROP ROTATIONS ...................................................................... 102
4.6. CONCLUSIONS ..................................................................................................................................... 103
5. USE OF MODELS TO ESTIMATE N-FIXATION........................................................................... 105
5.1. SIMPLE YIELD-BASED MODELS ............................................................................................................ 105
5.2. MORE COMPLEX MODELS .................................................................................................................... 106
5.3. CONCLUSIONS ..................................................................................................................................... 109
6. UTILISING N FROM FERTILITY-BUILDING CROPS ................................................................ 110
6.1. INTRODUCTION.................................................................................................................................... 110
6.2. FACTORS AFFECTING N MINERALISATION ........................................................................................... 111
6.3. NITROGEN LOSSES............................................................................................................................... 113
6.4. INTERACTIONS WITH CROP UPTAKE ..................................................................................................... 118
6.5. PREDICTING N RELEASE ...................................................................................................................... 120
6.6. CONCLUSIONS ..................................................................................................................................... 122
7. ROTATIONAL ASPECTS................................................................................................................... 123
7.1. FARM PRACTICES................................................................................................................................. 123
7.2. NUTRIENT BALANCES .......................................................................................................................... 125
7.3. CONSTRUCTING ROTATIONS ................................................................................................................ 128
7.4. COMPANION CROPPING (‘BI-CROPPING’)............................................................................................. 129
7.5. CONCLUSIONS ..................................................................................................................................... 130
8. CONCLUSIONS.................................................................................................................................... 131
8.1. HOW MUCH N IS FIXED UNDER UK CONDITIONS? ............................................................................... 131
8.2. MANAGEMENT TO OPTIMISE N ACCUMULATION.................................................................................. 132
8.3. RATE OF RELEASE OF FIXED N AND MINIMISING LOSSES...................................................................... 133
8.4. OTHER CONSIDERATIONS .................................................................................................................... 134
9. BIBLIOGRAPHY ................................................................................................................................. 139