To feed the earth : agro-ecology for sustainable development

This paper defines, describes, and argues the importance of, especially for tropical zones, an ecological approach to agriculture that differs profoundly from the industrial approach which has dominated agricultural research and development for decades. The ecological principles that form the basis for sustainable food production are covered in detail, including such concepts as: the distinction between ecosystems that are allowed to evolve undisturbed over time and those that are exploited prematurely; a notion of ecosystem stability based on balanced interactions among species (rather than on the mere presence of biological diversity) and a system"s ability to persist in the face of change; and a flexible use of the concept of ecosystem carrying capacity. A discussion of the ecosystem specific to agriculture - the agroecosystem - focuses on polyculture systems (in contrast to the monoculture systems which dominate industrial agriculture); included is a case study of such a system in Mexico and a review of recent agroforestry efforts. Stressing that ecology offers agriculture a set not of easy answers but of difficult questions, the authors outline some emerging agroecological principles: the need to understand the system as a whole, and the importance of maintaining energy efficiency. An analysis of policy issues covers the importance of agroecosystem research, and the need for national agricultural policies and international donors to support the development of ecologically sound agricultural systems. The final section presents an action plan for sustainable agriculture based on maintaining soil quality, ecological efficiency, agroecosystem stability, and diversity. Includes extensive references.