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.

To identify interventions which reduce health risks of consumers where highly polluted irrigation water is used to irrigate vegetables in West Africa, scientists worked over 5 years with farmers, market traders and street food vendors in Ghana. The most promising low-cost interventions with high adoption potential were analyzed for their ability to reduce common levels of pathogens (counts of fecal coliforms and helminth eggs). The analysis showed the combination potential of various interventions, especially on-farm and during vegetable washing in line with the World Health Organization (WHO) guidelines. The tested market-based interventions were important to prevent new or additional contamination.