List of Contributors xi
Preface xiii
1 Science and Organic Agriculture: An Introduction 1David Atkinson and Christine A. Watson
1.1 What is the Role of this Volume? 1
1.2 What is Organic Agriculture? 2
1.3 So What is Distinctive About its Science Base? 5
1.4 The Ecological Roots of Organic Production 6
1.5 Key Elements in the Science Context of Organic Agriculture 8
1.6 Some Areas of Different Science 10
1.7 Production Systems Compared 13
1.8 A Science Base for All Production 15
1.9 The Changing Context of Farming 18
References 21
2 Science, Research and Organic Farming 25Lawrence Woodward
2.1 Introduction 25
2.2 The Roots of the Approach 25
2.2.1 Is it a philosophical or political movement and cannot therefore be scientific? 26
2.2.2 Does it lack coherence except as a marketing exercise? 27
2.2.3 Is it inherently unscientific because it is based on concepts that are not explicable in rational scientific terms? 28
2.3 Agricultural Science: Some Reflections 30
2.4 Conclusion 32
References 32
3 Framing and Farming: Putting Organics in a Societal Context 33Pete Ritchie
3.1 Introduction 33
3.2 The Origin of Organics 34
3.3 The Argument from Economics: Is More Better? 35
3.4 The Argument from the Environment: Externalities Matter 37
3.5 The Argument from Ethics: Theres Something Wrong with the System 37
3.5.1 What is the Place of Humans in Nature? 38
3.5.2 What is Farming For, and What Makes for Good Farming? 40
3.5.3 How can the way we produce food promote social justice? 41
3.6 Aligning Organics with Social Justice 42
3.7 Conclusion 43
References 43
Further Reading 43
4 Soil Health and Its Management for Organic Farming 45Elizabeth A. Stockdale, Tony C. Edwards and Christine A. Watson
4.1 Introduction 45
4.2 Soil Components 47
4.2.1 Soil Parent Material and Profile Formation 47
4.2.2 Soil Organic Matter 48
4.2.3 Soil Organisms 48
4.3 Key Soil Processes in Agricultural Systems 51
4.3.1 Decomposition 51
4.4 Soil Structure Formation and Stabilisation 53
4.5 BelowGround Ecological Interactions 54
4.6 Nutrient Cycling and Management 56
4.6.1 Potassium (K) and Other Cations (Mg, Ca) 56
4.6.2 Nitrogen (N) 57
4.6.3 Phosphorus (P) 59
4.7 Impact of Agricultural Management Practices on Soil Function and Health 61
4.8 Cropping Systems 63
4.9 Intensive Grassland 65
4.10 Conclusion 66
References 68
5 Cropping Systems and Crop Choice 79Robin L. Walker
5.1 Farming Systems 79
5.2 Land Capability and Cropping System Choice 81
5.2.1 Rainfall 81
5.2.2 Temperature 81
5.2.3 Altitude and Topography 82
5.2.4 Soil 83
5.2.5 Markets 83
5.2.6 Traditions 83
5.2.7 Government Policy 84
5.3 How Land Capability is Used in Practice 84
5.4 Conclusion 85
References 85
6 Crop Rotations: The Core of Organic Production 87David Atkinson and Robin L. Walker
6.1 Introduction 87
6.2 The History of Crop Rotations 88
6.3 Rotations in Organic Production 91
6.4 The Ecological Science Base of Organic Production 94
6.5 Impact of Rotations on Soil Properties 95
6.5.1 Impact of Rotations on Soil Condition 95
6.5.2 Impact of Rotations on Nutrient Availability 98
6.5.3 Nitrogen Supply in Rotations 99
6.5.4 Phosphorus Supply in Rotations 100
6.6 Impact of Rotations on Crop Protection 103
6.7 Stockless Rotations 105
6.8 Conclusion 105
References 107
7 What Can Organic Farming Contribute to Biodiversity Restoration? 111Ruth E. Feber, Paul J. Johnson and David W. Macdonald
7.1 Why Conserve Farmland Biodiversity? 111
7.2 What Can Organic Farming Contribute to Biodiversity Conservation? 116
7.3 Effects of Organic Farming Vary with Taxa 118
7.4 How Rapid is the Effect of Conversion to Organic on Biodiversity? 120
7.5 Landscape Context and Species Traits 121
7.6 Wider Considerations 123
Acknowledgements 126
References 126
8 Optimising Crop Production in Organic Systems 133David Atkinson and Robin L. Walker
8.1 Introduction 133
8.2 Basic Issues 134
8.3 Light Interception: The Basis of All Production 136
8.3.1 Energy Capture 136
8.3.2 Canopy Duration 137
8.3.3 Stomatal Functioning 138
8.3.4 Crop Species 138
8.3.5 Crop Growth and Resource Partitioning 140
8.3.6 SoilRelated Factors 141
8.3.7 Consequences 142
8.4 What Current Issues Affect Choice of Crop Production System? 142
8.5 What Options Exist for Regulating Yields? 144
8.6 How Different are Conventional and Organic Yields? 145
8.7 The Environmental Impact of Organic Systems 147
8.8 Conclusion 148
References 148
9 Crop Production: Meeting the Nutrient Needs 151David Atkinson and Robin L. Walker
9.1 Introduction 151
9.2 Getting Nutrients into Organic Crops 152
9.3 What is the Impact of Differences in Soil Nutrient Supply? 154
9.4 Organic Manures: Recycling of Nutrient Sources 155
9.5 Crop Rotations 157
9.6 Cover Crops 158
9.7 Legumes 158
9.8 Soil Microbial Populations and Inoculation 159
9.9 The Impact of Different Soil Nutrients 160
9.9.1 Nitrogen: How Much N Does a Crop Need? 160
9.9.2 Phosphorus 162
9.9.3 Potassium 163
9.9.4 Sulphur 164
9.10 Conclusion 164
References 165
10 Crop Attributes Facilitating the Use of Soil Resources 169David Atkinson
10.1 Introduction 169
10.2 Nutrient Capture and Utilisation 171
10.2.1 Basic Issues 171
10.2.2 Nutrient Availability 172
10.3 The Functional Requirements of a Root System 172
10.3.1 Basic Issues 172
10.3.2 Relation of Root Activity to Soil Processes 172
10.3.3 The Impact of Root System Form 174
10.3.4 Variation Between Crop Species 175
10.3.5 Variation Within Crop Species 178
10.4 Case Studies 180
10.4.1 Case Study 1:Betula pendula 180
10.4.2 Case Study 2: Spring Barley 182
10.5 Root Dynamics and Carbon Inputs to the Soil 183
10.5.1 Root Dynamics 183
10.5.2 Root Longevity 184
10.6 Variation in Root Systems in Practice 185
10.6.1 Variation in Root Systems with Functional Significance 185
10.6.2 The Ability of the Crop Plant to Extract Nutrients from the Soil 188
10.7 Case Study 3: Apple 188
10.8 So How Much Root Does a Plant Need? 191
10.9 Conclusion 192
References 193
11 Mycorrhizal Activity, Resource and Microbial Cycles 199David Atkinson
11.1 Introduction 199
11.2 Mycorrhizal Establishment 199
11.3 Mycorrhizal Effects 201
11.4 The AMF Association 202
11.5 Effects on Plant Nutrition: Basic Mechanisms 203
11.6 Impact on Crop Nutrition 204
11.7 The Impact of AMF on Soil Structure 204
11.8 Carbon Flows into the Soil 204
11.9 The Impact of AMF on Adaptation to the Soil Physical Environment 205
11.10 The Impact of AMF on Plant Pathogens 206
11.11 Impact of AMF on Roots 206
11.12 Arbuscular Mycorrhizal Fungi and the Management of Soils 209
11.13 Conclusions: AMF and Root Functioning 209
References 209
12 Crop Protection and Food Quality: Challenges and Answers 213David Atkinson and Robin L. Walker
12.1 Introduction 213
12.2 Crop Protection Against Pests, Weeds and Diseases 214
12.3 Weed Control 215
12.4 Living with Crop Diseases 219
12.4.1 The Impact of AMF on Plant Pathogens 220
12.4.2 Plant VarietalBased Resistance 222
12.5 Pest Control 224
12.6 The Quality of Organic Crops and CropBased Foods 226
12.6.1 Varietal Selection 227
12.6.2 The Production System 228
12.6.3 Inputs Used as Part of the Cultural System 228
12.6.4 Inherent Attributes 230
12.6.5 Microbial Content and Chemical Contamination 231
12.7 Conclusion 231
References 232
13 Plant Breeding and Genetics in Organic Agriculture 237Thomas F. Döring and Martin S. Wolfe
13.1 Introduction 237
13.2 Plant Diversity in AgroEcosystems 238
13.2.1 Genetic Diversity 239
13.2.2 Species and Ecosystem Diversity 241
13.2.3 Effects of Crop Diversity: Types of Mechanisms 242
13.3 Crop Genetics in Complex and Dynamic Environments 244
13.3.1 The Organic Principle of Ecology 244
13.3.2 The Ecology of G × E Interactions 244
13.3.3 Implications of G × E Interactions for Testing Varieties for Organic Agriculture 245
13.3.4 Genetic Properties of Crops for Suitability in Organic Systems 248
13.3.5 Crop Genetics for Ecological Cropping Systems Design 249
13.3.6 Limitations of Crop Genetics and the Role of Plant Genetic Diversity 250
13.4 Crop Genetics for Health 250
13.4.1 The Organic Principle of Health 250
13.4.2 What is Health? 251
13.4.3 Connections Between Crop Genetics and Health 251
13.4.4 The Role of Plant Genetic Diversity for Health 256
13.5 Socioeconomics, Policies and Regulations 257
13.5.1 The Organic Principle of Fairness 257
13.5.2 Traditional Landraces and the Protection of Plant Genetic Resources 258
13.5.3 Sharing the Costs and Benefits of Plant Breeding 259
13.5.4 Hybrid Varieties in Organic Farming 259
13.6 Indeterminism and Crop Genetics 260
13.6.1 The Organic Principle of Care 260
13.6.2 Implications of the Care Principle for Crop Breeding 260
13.6.3 The Role of Plant Genetic Diversity for the Care Principle 261
13.7 Conclusion 261
References 262
14 Exploring the Systems Concept in Contemporary Organic Farming Research 273Christine A. Watson and Bruce D. Pearce
14.1 Introduction 273
14.2 The Importance of the Systems Concept in Organic Farming 274
14.3 How are Systems Reflected in Regulation? 275
14.4 Applying the Systems Concept to Organic Production 275
14.5 How is the Systems Concept Reflected in Organic Farming Research? 277
14.5.1 Example 1. Comparison of Production Systems 280
14.5.2 Example 2. Food Quality and Its Relation to Production Systems 281
14.5.3 Example 3. Weed Control 282
14.5.4 Example 4. Plant Breeding 282
14.6 Cautionary Tales 283
14.7 Are the Research Needs of Organic Farming Different from Conventional Farming? 283
References 284
15 Science Base of Organic Agriculture: Some Conclusions 289David Atkinson and Christine A. Watson
15.1 Introduction 289
15.2 Increasing the Contribution of Organic Agriculture to Global Food Production 291
15.3 Challenges to Organic Production 295
15.4 Conclusion 297
References 297
Index 299
