The symposium In the next decades, agriculture will have to cope with an ever-increasing demand for food and raw basic materials on the one hand, and with the necessity to use resources without further degrading or exhausting the environment on the other hand, and all this within a dynamic framework of social and economic conditions. Intensification, sustainability, optimizing scarce resources, and climate change are among the key issues. Organized thinking about future farming requires forecasting of consequences of alternative ways to farm and to develop agriculture. The complexity of the problems calls for a systematic approach in which many disciplines are integrated. Systems thinking and systems simulation are therefore indispensable tools for such endeavours. About 150 scientists and senior research leaders participated in the symposium 'Systems Approaches for Agricultural Development' (SAAD) at the Asian Institute of Technology (AIT), Bangkok, Thailand, in December 1991. The symposium had the following objectives: - to review the status of systems research and modeling in agriculture, with special reference to evaluating their efficacy and efficiency in achieving research goals, and to their application in developing countries; - to promote international cooperation in modeling, and increase awareness of systems research and simulation. The symposium consisted of plenary sessions with reviews of major areas in systems approaches in agriculture, plus presentations in two concurrent sessions on technical topics of systems research. Subjects of studies were from tropical and temperate countries.

Approaches to research on the causes and impacts of soil erosion have changed significantly over recent years. Whereas biophysical research traditionally utilized small, carefully-managed erosion plots, models and methods are now available to study impacts of broad scale management on the hydrology and water quality of catchments and even river basins. Corresponding research tools have been developed for social and economic analysis at the household, farm and community levels. This book reviews the latest developments in such soil erosion studies. These are considered on a matrix of scales, from plot to river basin, and from farm to national policy. Some chapters review background issues while others consider specific methods. Conclusions of working groups are presented in another chapter. The book is based on papers presented at a workshop held in Indonesia in November 1997, and includes authors from Europe, America, Australia and Asia, as well as from several of the CGIAR centers.

The degradation of land and water resources resulting primarily from agricultural activities has had enormous impact on human society. In order to alleviate this problem, an advanced understanding of the state of our resources and the process of degradation is needed. "Conserving Land, Protecting Water" includes an overview of existing literature focusing on global patterns of land and water degradation and discussions of new insights drawn from successful case studies on reversing soil and water degradation and their impact on food and environmental security.

This book is based on a workshop held in Zimbabwe, May 1999, organized by the Department of Research and Specialist Services (Zimbabwe) and the International Board for Soil Research and Management (IBSRAM). Reviewing the current state of knowledge on and the practical aspects of the management of Vertisols in Africa, this book also includes comparative chapters covering other parts of the world, such as India, Australia and Texas (USA).