ABSTRACT
The expansion of irrigation and increased efficiency in the use of irrigation water are among the most important opportunities for improving tropical agricultural productivity. The long-term, adverse effects of irrigation schemes also may include soil waterlogging, salinity, and alkalinity, unless adequate provisions are made for drainage and leaching. Dry season monitoring of waste disposal in rivers and of the quantity of water taken for irrigation can mitigate some problems, although the enforcement of water quality regulations is frequently difficult. The losses of forests, interred minerals, and fertile land due to reservoir inundation are environmental and economic costs that need to be weighed against the benefits generated by irrigation. Trickle irrigation not only conserves water, but can also minimize such problems as salinization and waterlogging. Sedimentation of irrigation works and excessive silt deposit on fields can cause extensive damage. The intensification of agricultural production through irrigation is closely linked with increased and sometimes excessive use of biocides and fertilizers.
