Agriculture in the tropics is afflicted by a variety of related crises. Farmers are compelled to move to forested areas and the consequent clearing of land, together with bad soil management, has devastating consequences including soil erosion, desertification, nutrient leaching, salinization and acidity. This book tackles the difficulties farmers have faced since the beginning of agriculture and provides an overview of concepts and ideas in sustainable agriculture. It explains how biological processes need to be understood, and diversity encouraged, in order to manage soil effectively. It suggests practical ideas for improving the sustainability of farm systems in a tropical context.