The first premise of this book is that farmers need access to options for improving their situation. In agricultural terms, these options might be manage­ ment alternatives or different crops to grow, that can stabilize or increase household income, that reduce soil degradation and dependence on off-farm inputs, or that exploit local market opportunities. Farmers need a facilitating environment, in which affordable credit is available if needed, in which policies are conducive to judicious management of natural resources, and in which costs and prices of production are stable. Another key ingredient of this facilitating environment is information: an understanding of which options are viable, how these operate at the farm level, and what their impact may be on the things that farmers perceive as being important. The second premise is that systems analysis and simulation have an impor­ tant role to play in fostering this understanding of options, traditional field experimentation being time-consuming and costly. This book summarizes the activities of the International Benchmark Sites Network for Agrotechnology Transfer (IBSNAT) project, an international initiative funded by the United States Agency for International Development (USAID). IBSNAT was an attempt to demonstrate the effectiveness of understanding options through systems analysis and simulation for the ultimate benefit of farm households in the tropics and subtropics. The idea for the book was first suggested at one of the last IBSNAT group meetings held at the University of Hawaii in 1993.

Preface. Acronyms. 1. Overview of IBSNAT; G. Uehara, G.Y. Tsuji. 2. Data for Model Operation, Calibration, and Evaluation; L.A. Hunt, K.J. Boote. 3. Soil Water Balance and Plant Water Stress; J.T. Ritchie. 4. Nitrogen Balance and Crop Response to Nitrogen in Upland and Lowland Cropping Systems; D.C. Godwin, U. Singh. 5. Cereal Growth, Development and Yield; J.T. Ritchie, et al. 6. The CROPGRO Model for Grain Legumes; K.J. Boote, et al. 7. Modeling Growth and Development of Root and Tuber Crops; U. Singh, et al. 8. Decision Support System for Agrotechnology Transfer: DSSAT v3; J.W. Jones, et al. 9. Modeling and Crop Improvement; J.W. White. 10. Simulation as a Tool for Improving Nitrogen Management; W.T. Bowen, W.E. Baethgen. 11. The Use of a Crop Simulation Model for Planning Wheat Irrigation in Zimbabwe; J.F. MacRobert, M.J. Savage. 12. Simulation of Pest Effects on Crops Using Coupled Pest-Crop Models: The Potential for Decision Support; P.S. Teng, et al. 13. The Use of Crop Models for International Climate Change Impact Assessment; C. Rosenzweig, A. Iglesias. 14. Evaluation of Land Resources Using Crop Models and a GIS; F.H. Beinroth, et al. 15. The Simulation of Cropping Sequences Using DSSAT; W.T. Bowen, et al. 16. Risk Assessment and Food Security; P.K. Thornton, P.W. Wilkens. 17. Incorporating Farm Household Decision-Making within Whole Farm Models; G. Edwards-Jones, et al. 18. Network Management and Information Dissemination for Agrotechnology Transfer; G.Y. Tsuji. 19. Crop Simulation Models as an Educational Tool; R.A. Ortiz. 20. Synthesis; G. Uehara.