There is much scope to close yield gaps by some 2-4 tonnes per hectare in irrigated rice production in West and Central Africa (Table 4.1). Promising research avenues include development of low-cost water management, weed-competitive and nutrient-responsive rice varieties (Box 4.2), and site-specific soil fertility management. These actions address the current major biophysical factors limiting yields. An integrated rice management approach should raise production levels, optimize profits, preserve soil quality and protect natural resources. The step-wise integration of new technology options should take place with the full participation of farmers (Ndiaye et al., 2004).
About 40 percent of rice has been grown so far in upland rainfed conditions in West Africa. Since rice is a semi-aquatic plant, the yield is higher in lowland conditions than in upland conditions. In Africa, particularly in West Africa, there are vast areas of unused land in the inland valley bottoms, which correspond to the rainfed lowlands shown in Table 4.1. Such wet or flooded inland valleys are difficult to use for crops other than rice. Since the upland is competitive with the cultivation of upland crop species, it is preferable to grow more rice in the lowland inland valleys. Further exploitation of inland valleys with increased rice productivity is an urgent issue for food security, particularly in West Africa.