Conventional water management in lowland rice aims at keeping the fields continuously submerged. Initially, a shallow water layer of 2-3 cm is maintained, but with the growing of the crop, the water depth is increased to about 10 cm. Because of the continuous presence of ponded water, there are large losses of water by evaporation from the water surface and by vertical percolation to below the root zone. These water outflows do not contribute to crop growth and are therefore called “unproductive”. These unproductive losses can be minimized through sound field water management strategies.

The decreasing availability of water for irrigated rice threatens food security in Asia in general and the livelihood of farmers in particular. Also, the increasing scarcity of water means that costs of its use and resource development are increasing dramatically. This is the reason why experts introduced different effective technologies to mitigate the increasing water scarcity.  It has also  been found out that  new ways of growing rice need to be developed that use less water than conventional lowland rice.

In this module, we present technology options to help farmers manage irrigation water efficiently and soundly, save water and cope with water scarcity at the field level. The way to deal with reduced (irrigation or rain) water inflows to rice fields is to reduce the nonproductive outflows by: