Water-Efficient Irrigation Technique for Rice

Abstract

Water used for growing irrigated rice in most Asian countries is very high. For a 4.0 t/ha rice yield about 5,000 liters of water is used on the farm to produce each kg of rice. A major portion of the water is lost through deep percolation. Studies of alternative methods of managing water conducted on farmer's fields rice with day loam soil and average water table depth of 95 cm for four consecutive dry seasons showed that if soil saturation condition is maintained in stead of the traditional shallow flooding of water throughout the season, about 40% or more of water used in the traditional practice could be saved without yield reduction. But, when weed control was inadequate, yield was reduced by an average of 30%. In such conditions, continuous shallow flooding up to panicle initiation and then continuous saturation thereafter saved about 35% of irrigation water without yield reduction. Soil nitrate and ammonium concentrations were similar in both continuously shallow- flooded and saturated soil water regimes, implying that plant N availability is not adversely affected when the latter water regime is maintained.