Integrated Irrigation and Drainage Practices to Enhance Water Productivity and Reduce Pollution in a Rice Production System

Water‐saving irrigation and controlled drainage have been separately practised in many countries to increase water use efficiency and reduce non‐point source pollution while maintaining crop yields. In a two‐year field experiment in the Gaoyou Irrigation District of South China, water use, crop yield, and pollution loads were monitored in an integrated water‐saving irrigation and controlled drainage (WSI‐CD) system and an unregulated system. For both 2007 and 2008, irrigation water productivity (WP I ) and gross water productivity (WP G ) of the WSI‐CD were 45.3 and 31.6% higher than those of the unregulated system. While evapotranspiration water productivity (WP ET ) of the WSI‐CD was similar to or even less than that of the unregulated system, this indicated that a reduction in irrigation water did not cause water stress and the WSI‐CD only reduced non‐productive water use. In 2008, the amount of drainage water from WSI‐CD (1956 m 3 ha ‐1 ) was far less than the unregulated system (4255 m 3 ha ‐1 ), and TN and TP loads were significantly reduced by 50.9 and 52.3%.The water‐saving irrigation practice contributed to lower drainage potential, while the controlled drainage reduced irrigation requirements. The integrated WSI‐CD practices seemed to have the desirable functions of water saving and pollutant reduction.