Not AvailableAmong the surface irrigated crops in general and command areas in particular, rice is the dominant one in terms of percentage share of water used for irrigation to crops. Rice is the staple food for nearly half of the world’s population, most of whom live in developing countries. More than 80 per cent of the developed freshwater resources in Asia are used for irrigation purposes and about half of the total irrigation water is used for rice production (Bhuiyan, 1992 and Dawe et al., 1998). Rice grown under traditional practices in mediumto heavy-textured soils in the Asian tropics and subtropics requires between 700 and 1,500 mm of water (Bhuiyan, 1992).Tuong and Bowman (2003) estimate that, by 2025, about 2 million ha of ...