The Science Beneath Organic Production

ABOUT THE EDITORS

DAVID ATKINSON was formerly Vice Principal at the Scottish Agricultural College and Chair of Falkland Rural Enterprises, an organic farming company. He continues to study the ethical implications of emerging biotechnologies.

CHRISTINE A. WATSON leads soil science research at SRUC. She has extensive experience of research in organic farming and is involved in managing and teaching SRUC's postgraduate course in Organic Farming.

List of Contributors xi

Preface xiii

1 Science and Organic Agriculture: An Introduction 1 
David 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 25
Lawrence 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 33
Pete 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: There’s 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 45
Elizabeth 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 Below‐Ground 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 79
Robin 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 87
David 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? 111
Ruth 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 133
David 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 Soil‐Related 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 151
David 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 169
David 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 199
David 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 213
David 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 Varietal‐Based Resistance 222

12.5 Pest Control 224

12.6 The Quality of Organic Crops and Crop‐Based 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 237
Thomas F. Döring and Martin S. Wolfe

13.1 Introduction 237

13.2 Plant Diversity in Agro‐Ecosystems 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 273
Christine 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 289
David 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

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