An imbalance among natural resources, population, and basic human needs exists in many regions, but is particularly acute in the developing countries of the warm seasonally dry tropics (WSDT). The WSDT are found primarily in Sub-Saharan Africa, Southwest and Southeast Asia, Central and South America, and northern Australia, and include approximately 21 percent of the world's population. Although the region's soil and water resources vary substantially, as a whole the dry tropics are resource-poor, and large areas are heavily exploited, leading to severe pressure on the resource base. Three factors render these regions particularly fragile: insufficient precipitation, low soil fertility, and rapid loss of soil organic matter in cultivated soils. As human and animal populations rapidly increase (except in Australia), and thus require more intensive cropping systems, traditional methods of coping with risk and drought in the WSDT-nomadism and long fallow periods-are being forced to change. Extensive research and scientific knowledge exists which can be used for developing sustainable management systems in the WSDT. Basic principles of managing soil and water resources are known and are transferable to these countries. Site-specific technologies based on these principles, however, must be validated and fine-tuned for different sub-ecoregions. The key elements include the care and stewardship of the land through proper methods of land clearing; early sowing with viable seed; frequent use of cover crops and multiple or mixed cropping systems; and adequate fertilization. Providing guidelines about these basic principles-the objective of this publication-may facilitate local validation and adaptation of improved technologies. The paper briefly describes the ecoregion, identifies the main constraints, and offers a series of technological options for sustainable development through the conservation of soil moisture, the prevention and control of soil erosion, and the improvement of soil fertility. The paper is designed to serve as a guide for policymakers, project managers, and agriculture operations staff in evaluating options and designing programs for the WSDT. References have been provided for those requiring additional background material or more technical information.

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