CROP–SOIL SIMULATION MODELS APPLICATIONS IN DEVELOPING COUNTRIES Crop–Soil Simulation Models Applications in Developing Countries Edited by Robin Matthews and William Stephens Institute of Water and Environment Cranfield University Silsoe UK CABI Publishing CABI Publishing is a division of CAB International CABI Publishing CABI Publishing CAB International 10 E 40th Street Wallingford Suite 3203 Oxon OX10 8DE New York, NY 10016 UK USA Tel: +44 (0)1491 832111 Tel: +1 212 481 7018 Fax: +44 (0)1491 833508 Fax: +1 212 686 7993 Email: [email protected] Email: [email protected] Web site: www.cabi-publishing.org ©CAB International 2002. All rights reserved. No part of this publication may be reproduced in any form or by any means, electronically, mechanically, by photocopying, recording or otherwise, without the prior permission of the copyright owners. A catalogue record for this book is available from the British Library, London, UK. Library of Congress Cataloging-in-Publication Data Crop–soil simulation models: applications in developing countries/edited by Robin Matthews and William Stephens. p. cm. Includes bibliographical references. ISBN 0-85199-563-2 (alk. paper) 1. Crops and soils—Computer simulation. 2. Crops— Computer simulation. 3. Soils—Computer simulation. 4. Crops and soils—Mathematical models. 5. Crops— Mathematical models. 6. Soils—Mathematical models. I. Matthews, Robin B. II. Stephens, William, Ph. D. S596.7.C72 2002 630’.1’13––dc21 2001052815 ISBN 0 85199 563 2 Typeset by Wyvern 21 Ltd, Bristol. Printed and bound in the UK by Cromwell Press, Trowbridge. Contents Contributors ix Abbreviations x Preface xiii 1 Introduction 1 Robin Matthews Part 1: Models as tools in research 7 2 Models as Research Tools 9 Robin Matthews 3 Crop Genotype Improvement 13 Robin Matthews 3.1 Identification and Evaluation of Desirable Plant Characteristics 14 3.2 Environmental Characterization 19 3.3 G×E Interactions 22 4 Crop Management 29 Robin Matthews 4.1 Yield Gap Analysis 29 4.2 Soil Surface Management 33 4.3 Planting 33 4.4 Water Management 37 v vi Contents 4.5 Nutrient Management 41 4.6 Pest and Disease Management 47 4.7 Weed Management 49 4.8 Harvesting 53 5 Cropping and Farming Systems 55 Robin Matthews 5.1 New Crops and Cropping Systems 55 5.2 Evaluating Sustainability 58 5.3 Farm Household Models 63 6 Regional and National Planning 69 Robin Matthews 6.1 Linear Programming Approaches 70 6.2 Dynamic Simulation Approaches 74 6.3 Limitations 76 6.4 Impact 77 7 Global Level Processes 79 Robin Matthews and Reiner Wassmann 7.1 Impact of Climate Change on Rice Production 80 7.2 Greenhouse Gas Production 86 7.3 The El Niño-Southern Oscillation 90 Part 2: Models as decision-support tools 93 8 Decision Theory and Decision Support Systems 95 William Stephens 8.1 Decisions, Decisions, Decisions 95 8.2 Characteristics of Decision Making 95 8.3 Definitions of Decision Support Systems 97 8.4 Spatial and Temporal Scale 101 8.5 Application 102 9 Tools to Support Operational Decision Making 105 William Stephens and Tabitha Middleton 9.1 Pest Management 105 9.2 Irrigation Scheduling 109 9.3 Optimizing Fertilizer Application 112 9.4 Multiple Decision Support 113 9.5 Deciding whether to Implement Emergency Relief 114 10 Tools to Support Strategic Decision Making 117 William Stephens and Tabitha Middleton 10.1 Land-use Planning 117 Contents vii 10.2 Planning for Climate Change 120 10.3 Crop Forecasting 121 10.4 Irrigation Planning 123 10.5 Assessing the Benefit of Proposed New Technologies 124 10.6 Planning Optimum Farm Management Strategies in Collaboration with Extension Services and Farmers 125 11 Why has the Uptake of Decision Support Systems been so Poor? 129 William Stephens and Tabitha Middleton 11.1 Model Construction Constraints 132 11.2 Marketing and Support Constraints 136 11.3 Technical and Operational Constraints 141 11.4 User Constraints 143 11.5 Other Constraints 144 11.6 Criteria for Success of Decision Support Systems 145 11.7 Risks Associated with using Decision Support Systems 146 Part 3: Models as tools in education and training 149 12 Using Models as Tools in Education and Training 151 Anil Graves, Tim Hess and Robin Matthews 12.1 Introduction 151 12.2 Using Existing Simulation Models 152 12.3 Model Building 163 12.4 Transferring the Systems Approach to Less-developed Countries 165 12.5 Considerations for Education and Training 173 12.6 Limitations and Constraints of Models in the Educational Context 178 Part 4: Have crop models been useful? 183 13 Who are Models Targetted at? 185 Robin Matthews 13.1 Researchers 186 13.2 Consultants 187 13.3 Educators and Trainers 188 13.4 Policy Makers 189 13.5 Extensionists 190 13.6 Farmers 191 14 Impacts of Crop–Soil Models 195 Robin Matthews, William Stephens and Tim Hess 14.1 Limitations to Use 195 viii Contents 14.2 Constraints to the Uptake of Crop Models 196 14.3 Characteristics for Impact 198 14.4 Concluding Remarks 205 Part 5: The way forward 207 15 Where to Now with Crop Modelling? 209 Robin Matthews 15.1 Modelling Rural Livelihoods 211 15.2 Contribution to Crop Improvement Programmes 217 15.3 Making Information Available – Decision Support Systems 219 15.4 Integrating Model Use into Research and Extension Projects 221 15.5 Environmental Research 224 15.6 Building Modelling Capacity 226 15.7 Further Crop–Soil Model Development 227 15.8 Summary 229 16 Concluding Remarks 231 Robin Matthews and William Stephens References 235 Appendix: Personal Communications 267 Index 271 Contributors A. Graves, Institute of Water and Environment, Cranfield University, Silsoe, Bedfordshire MK45 4DT, UK. T. Hess, Institute of Water and Environment, Cranfield University, Silsoe, Bedfordshire MK45 4DT, UK. R. Matthews, Institute of Water and Environment, Cranfield University, Silsoe, Bedfordshire MK45 4DT, UK. T. Middleton, Institute of Water and Environment, Cranfield University, Silsoe, Bedfordshire MK45 4DT, UK. W. Stephens, Institute of Water and Environment, Cranfield University, Silsoe, Bedfordshire MK45 4DT, UK. R. Wassmann, Fraunhofer Institute for Atmospheric Environmental Research, Kreuzeckbahnstrasse 19, 82467 Garmisch-Partenkirchen, Germany. ix