Myths and Scientific Realities of Agroforestry as a Strategy for Sustainable Management for Soils in the Tropics

Abstract

The introduction (Part I) to this discussion and review notes that rapid deforestation in rain forest zones is a major environmental issue. Two strategies for halting deforestation are by increasing production from existing (cleared) lands in a sustainable way, and by restoring the productivity of degraded soils. For either of these strategies the use of trees and tree-based farming systems may be the key to achieving sustainability. In this context, in Part II the paper gives an outline of farming systems in the tropical rain forest zone, indicating the predominant types, the characteristics of traditional farming systems in regions of shifting cultivation, and their classification (on the basis of type of rotation, cropping intensity, crop type, and crop/animal associations). Part III discusses the need for introducing permanently sustainable farming systems under 3 headings: Causes of success of traditional farming systems; Some alternative farming systems (large-scale mechanized farming; ranching and pasture development; and forestry systems, including monocultures, taungya, woody species in natural and planted fallows, and trees with crops on compound farms or in home gardens); and Agroforestry systems (rotational agroforestry, including shifting cultivation and improved fallows intercropping; and agrosilvopastoral systems). Part IV is an account of the practice of alley cropping, and includes data on food crop growth and yield, erosion control, and soil fertility. Part V discusses the transfer of alley cropping technologies, and Parts VI-VIII research priorities, approaches to research, and linking training with research. The final part (IX, Potential of agroforestry: myth or reality) addresses the question of sustainability under the headings agronomic yield, economic assessment, soil properties and research priorities.