ABSTRACT
Management of the resources of land, soils, and water in the lowland reaches of major watersheds involves heavy investment in irrigation and drainage in addition to the investment concentrated in the urban areas. As in upper watersheds, detailed land-use planning and management are required in the lowland areas of river basins. Tropical lowland alluvial areas often combine cultivatable soils, accessible water supplies, and year-round growing temperatures. Although technical solutions to most management problems of alluvial lowlands are now known, land affected by salinity is still the largest remaining undeveloped food resource in the Third World. In order to sustain crop productivity, commercial farmers throughout the world use fertilizers, but most subsistence farmers of the tropics do not yet do so. In 1966, population growth and poor weather had brought the subcontinent to the brink of famine. By a courageous decision, the government imported 20,000 tons of the new dwarf wheats from Mexico, together with extra fertilizers to grow them.
