• Contour cropping and terracing;

• Biocontrol and other integrated pest management strategies;

• A variety of agroforestry systems that mix crops, trees, livestock, and other components; and

• Intercropping, double cropping, and other mixed cropping methods that allow for more efficient uses of on-farm resources.

Sustainable practices to improve productivity and conserve soil, water, and biotic resources can provide farmers with alternatives to continued clearing of forests. Based on recent research in Peru, for example, it is estimated that for every 1 ha of land put into sustainable soil management technologies by farmers, 5 to 10 ha per year of forest could be spared (Sanchez, 1991; Sanchez et al., 1990). The potential of sustainable agricultural practices to reduce deforestation will depend on the location. For example, the sustainable use of secondary forest fallows provides a viable alternative to primary forest clearing. Many of the degraded or unproductive pastures or croplands resulting from poor management practices can also be reclaimed.

The particular methods that are most appropriate in any given locality will vary both within and among the world's humid tropic regions. Local needs and opportunities, ecological circumstances, economic opportunities, and social and cultural mores, as well as the status of land and water resources, will determine which methods are most suitable. Sustainable agricultural systems cannot, in this sense, be imported. Although specific technologies can be more freely introduced, they must be adopted to the inherent opportunities and limitations of local agroecosystems.

The transition to more sustainable agricultural and land use systems is not without difficulty, particularly in the early stages. In many cases, substantial initial investments of time, labor, and money are required (for example, to construct terraces or to reforest steep slopes). In some cases, the transition requires significant changes in current farming practices and land uses (for example, restrictions on the burning of biomass). Against these short-term effects must be weighed the long-term benefits of these investments and changes. They include the following:

• Reduced pressure on primary forests and the mitigation of deforestation 's effects;

• Preservation of species and germplasm diversity within the agroecosystem;

• Reduction in the amounts of carbon dioxide and other greenhouse gases released into the atmosphere;

• Conservation of soil, nutrients, and water resources;