Study of Spatial Water Requirement of Rice under Various Crop Establishment Methods Using GIS and Crop Models

Application of crop simulation models at larger spatial scales is very essential to develop best management practices in order to maximize yields and reduce environmental pollution. In the present study, spatial analysis of long- term simulations were carried out with DSSAT spatial analysis tool linked with GIS to estimate irrigation requirements and nitrate leaching under alternate rice establishment methods in the Wargal watershed, Andhra Pradesh, India. Rice yields were compared among three management scenarios: rainfed, aerobic and flooded systems. Grain yield, seasonal water balance components, nitrate leaching and water use efficiency were calculated, visualized and mapped with GIS. The rice productivity increased by 22% and 27% under aerobic and flooded management compared to rainfed rice. The adoption of new water efficient aerobic rice cultivation in the watershed resulted in 36% water saving with a relatively small yield reduction of 4%, thus increasing the water productivity to 0.77 g kg-1 in aerobic compared to 0.56 g kg-1 in flooded rice. The aerobic rice method reduced the overall water pumping hours to 88 h ha-1 during rice crop season compared to 299 h ha-1 with flooded rice cultivation, resulting in 71% energy savings