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close this bookAbstracts on Sustainable Agriculture (GTZ; 1992; 423 pages)
Open this folder and view contentsAbstracts On Traditional Land-Use Systems
Open this folder and view contentsAbstracts on farming systems research and development
Open this folder and view contentsAbstracts on integrated systems
Open this folder and view contentsAbstracts on cropping system
close this folderAbstracts on agroecology
View the documentAcknowledgements
View the document1. Rural common property resources: a growing crisis.
View the document2. Making haste slowly: strengthening local environmental management in agricultural development.
View the document3. Farming for the future: an introduction to low-external-input and sustainable agriculture.
View the document4. Public policies affecting natural resources and the environment.
View the document5. Human development and sustainability.
View the document6. Caring for the earth - a strategy for sustainable living.
View the document7. Agriculture and natural resources: a manual for development workers.
View the document8. Environmental guidelines for resettlement projects in the humid tropics.
View the document9. Saving the tropical forests.
View the document10. Values for the environment, a guide to economic appraisal.
View the document11. Alcohol fuels - options for developing countries.
View the document12. Diffusion of biomass energy technologies in developing countries.
View the document13 When aid is no help: how projects fail, and how they could succeed.
View the document14. Natural resources and the human environment for food and agriculture.
View the document15. World development report 1992 - development and the environment.
View the document16. Species interactions and community ecology in low external-input agriculture.
View the document17. Development strategies and natural resource management for humid tropical lowlands.
View the document18. Environmental management of the northern zone consolidation project in Costa Rica: strategies for sustainable development.
View the document19. Environmental assessment: the valles altos project in Bolivia.
View the document20. Environmental crisis in Asia-Pacific.
Open this folder and view contentsAbstracts on agrometeorology
Open this folder and view contentsAbstracts on agroforestry
Open this folder and view contentsAbstracts on homegardens
Open this folder and view contentsAbstracts on seed production
Open this folder and view contentsAbstracts on plant protection
Open this folder and view contentsAbstracts on water management
Open this folder and view contentsAbstracts on soil fertility
Open this folder and view contentsAbstracts on erosion and desertification control
Open this folder and view contentsAbstracts on potential crops for marginal lands

16. Species interactions and community ecology in low external-input agriculture.

American J. of Alternative Agriculture, II, No. 4, 1987, pp. 160

External production inputs have contributed greatly to the remarkable increases in crop yields achieved during the past several decades. These inputs take many forms, including fertilizers, pesticides, irrigation water, various soil amendments, machinery and labour. Most of these inputs have been developed to both stimulate farm system output as well as replace materials that have been removed with the harvest. Limited concern has been given to the long-term availability of these inputs as long as farming produced a net profit. Relatively little attention was paid to understanding the biological and ecological bases of interactions occurring within the cropping system as long as such interactions were not considered detrimental to yields. But today agriculture is confronted with the need to assess the long-term sustainability of its production practices. It must consider the availability and cost of inputs and the impacts of conventional practices on the environment, food safety, and the quality of life for people involved in food production and consumption. In essence it is now as or more important to understand agroecosystems processes that promote productivity in the short term and sustain it over the long term than it is to concentrate on how much is produced.

Polyculture systems can be managed for nutrient cycling efficiency and pest and disease regulation using knowledge of multi-trophic level interactions and application of recent developments in mutualism and competition theory. A mechanistic model of additive and removal reactions on the environment is proposed as a means of studying species interactions.

The agroecosystem can be examined as a complex set of species assemblages with many levels of organization that build upon the basic understanding of the ecology of interactions at the individual organism level, emerging at the ecosystem level to understand the dynamics of what makes the entire system function. This is especially important as the understanding of ecosystem level processes of sustainable agriculture then interface with yet more complex aspects of the social and economic systems within which agroecosystems function. Eventually such an integration of social system and ecological system knowledge about agricultural processes will not only lead to a reduction in external inputs used for maintaining productivity, but will also permit the evaluation of such emergent qualities of agroecosystems on long-term environmental quality, the importance of the human element to production, the long-term effects of different farm input/output strategies, and the relationship between economic and ecological components of sustainable agroecosystem management.

It is time to redirect a large portion of the resource that have generated all of the knowledge about single-species cropping systems towards the integration of both ecological and agronomic knowledge, with a broader goal of developing the ability to quantify the ultimate mergent quality of the agroecosystem - its sustainability. This is an extremely complex process, requiring a systems-level approach and the interaction of many disciplines, but with the outcome of being able to understand where and how effective change in agriculture can come about.

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Latin America, humid tropics, lowlands, review, conference, natural resources, development strategies, protected areas, ecotourism, nontimber forest products, indigenous agriculture, pastures, plantation agriculture, plantation forestry


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