The problem of shortage of water to crops can be resolved by increasing total water supply available to plants, increasing water use relative to other losses and efficient management of scarce water. Biophysically, solutions to many of the problems will require the improvement of soil, water, and crop management at the field, plot, and farm level: first, to increase the capture and retention of incoming (rain) water; and second, to maximize the proportion of that water productively transpired by the crop. Dry land agriculture under rain fed conditions is found mainly in Africa, the Middle East, Asia, and Latin America. In the harsh environments of Sub-Saharan Africa (SSA) and West Asia and North Africa (WANA), water is the principal factor limiting crop yield. A review has been carried out on soil and crop management research that can increase the water use efficiency. The WANA production systems are dominated by cereals, primarily wheat in the wetter and barley in the drier areas, in rotation with mainly food legumes such as chickpea, lentil and forage legumes. The SSA production systems are generally characterized by cereal/legume mixed-cropping dominated by maize, millet, sorghum, and wheat. The major constraints in both regions to crop production are low soil fertility, insecure rainfall, and low-productive genotypes, low adoption of improved soil and crop management practices, and lack of appropriate institutional support. Different cropping systems and accompanying technologies are discussed. Results indicate that there is an advantage to apply these technologies but being function of socio-economic and bio-physical conditions. It is recommended that future research focuses on integrated technology development while taking into account also different levels of scale such as field, village, and watershed.
Adaptation of the CROPGRO Model to Simulate Yield of Fresh-market Tomato