Productive water use in aerobic rice cultivation

Studies were conducted to evaluate both lowland and aerobic rice performances under different irrigation methods and soil moisture regimes. Results showed that aerobic rice cultivated under overhead sprinkler irrigation required least amount of water but more susceptible to foliar diseases. With supplementary irrigation, grain yield obtained ranged from 2.2 to 3.6 t/ha and the seasonal field water requirement was between 442 and 763 mm. Light and frequent irrigation was better when compared to heavy and occasional irrigation to avoid unnecessary water stress that could cause yield reduction. As much as 50% yield reduction was recorded if water stress occurred during heading and early grain formation periods. Despite lower crop yield, studies showed that aerobic rice cultivation used much less water for production. This in turn improved water productivity from 0.4 to 0.6 kg/m3 compared to irrigated wetland rice. The reduction in the water used was mainly attributed to the reduced seepage and percolation losses, decrease in evaporation since there was no standing water in the field, and also water required during pre-saturation period for land puddling was completely discarded