Alternate Wet/Dry Irrigation in Rice Cultivation: A Practical Way to Save Water and Control Malaria and Japanese Encephlitis

Abstract

"Due to increasing scarcity of freshwater resources that are available for irrigated agriculture, in the future, it will be necessary to produce more food with less water. More irrigated land is devoted to rice than to any other crop. One method to save water in irrigated rice cultivation is the intermittent drying of the rice fields instead of keeping them continuously flooded. This method is referred to as alternate wet/dry irrigation (AWDI). Apart from the water saving potential of AWDI there are also potential human health benefits. Rice fields provide a habitat for mosquitoes to lay their eggs, and rice agrosystems have traditionally been associated with mosquito-borne diseases, especially malaria and Japanese encephalitis. If rice fields are dried, as in AWDI, the mosquito larvae will die and less adult mosquitoes will be produced in the rice fields. This could lead to a lower incidence of malaria and Japanese encephalitis. In certain areas and under the right conditions, AWDI is a promising method in irrigated rice cultivation with dual benefits of water saving and human disease control, while maintaining rice yields at least at the same level. However, many factors play a role in determining the success or failure of AWDI. Some of these factors can be influenced, such as irrigation infrastructure and irrigation management capacity, while others cannot be, such as rainfall and soil conditions. The increased productivity of water, not the mosquito control is likely to be the critical factor that will make farmers and irrigation department officials adopt AWDI in water-scarce areas. This report reviews previous studies on AWDI with a focus on mosquito vector control, water saving, and rice yields. Examples are given from a number of countries and recommendations are provided for further studies."