A central theme of this book is the demonstration of the need for the development and widespread adoption of alternatives to the high-energy-input agriculture of the green revolution - alternatives characterized by low energy use, small-scale intensive use of labour, concern for long-term sustainability, low use of commercial fertilizers and insecticides, and often combining trees and other crops (agroforestry). The studies which form the basis of the book were undertaken on the initiative of the Committee on Population Resources and the Environment of the American Association for the Advancement of Science, which set up 3 working groups covering the subjects of food and population, soil and water and agroforestry. The results of this work are presented in 11 chapters, which are grouped into 4 parts: I, Overview (chapters 1-2); II, Soil and water resources (chapters 3-5); III, Productive sustainable systems: agroforestry (chapters 6-10); and IV, Summary (chapter 11). The work of the different members of the study groups has been restructured from the original drafts produced, so the chapters do not each have separate authors, although those primarily responsible for each contribution are noted at the beginning of each part of the book. The chapters are: (1) Food production; (2) Population change: global trends and future implications; (3) Soil and land; (4) Soil erosion; (5) Water; (6) Integrated resource management systems - definition and assessment; (7) Examples, case studies, and models; (8) Research challenges: ecosystems and economics; (9) Social aspects of resource management systems; (10) A sociological analysis of alternative agriculture; and (11) Observations and conclusions. References are given at the end of each chapter and there are 2 appendices (listing members of the Committee on Population, Resources and the Environment 1984-89, and of its working groups; and giving acronyms of relevant organizations), and a subject index. (CAB Abstracts)