Maize is the staple food crop for much of southern Africa and is largely produced under rain-fed conditions. Maize requires 500-800 mm of well-distributed rainfall during the growing period. Because of its shallow rooting system that cannot draw water from soil depths greater than 80 cm, maize is highly sensitive to water stress. Drought stress and poor soil fertility are the two most important physical factors limiting rain-fed crop production in southern Africa (Heisey and Edmeades, 1999). Drought stress affects maize production at three critical stages of plant growth: during establishment, at flowering, and during middle to late grain filling. A farmer confronted with an early-season drought has several management options. The options include replanting, planting a shorter maturing cultivar, or planting a different crop that matures more rapidly or is more drought tolerant than the original crop.
A mid-season drought is more devastating than drought at the beginning or end of the season. A crop such as maize is more susceptible to drought stress during the mid-season when the plant flowers. At this stage, the farmer has no management options to respond to drought stress unless irrigation is available. To minimize water stress-related fluctuations in crop yield, a number of drought mitigation strategies have evolved across southern Africa. The most common strategies include the promotion of sustainable agricultural practices such as growing drought-tolerant crops or varieties, minimum tillage systems, water conservation, building dams for small irrigation projects, building sufficient grain reserves, and having crop mixes that minimize impact of drought on food availability.
Through financial support from the United Nations Development Programme, the Belgian government, NOAA, and the World Bank, a regional Drought Monitoring Center was set up in Harare, Zimbabwe for the purpose of providing a regionally coordinated drought early warning system in 1990. The center post-processes global climatic data sets and seasonal climate prediction products received from international climate prediction centers to produce regional forecasts for seasonal precipitation. These forecasts are disseminated to national meteorological services and other concerned agencies in the subregion.
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