Application of DSSAT-CERES-Wheat model to simulate winter wheat response to irrigation management in the Texas High Plains

Winter wheat (Triticum aestivum L.) is a major crop in the semi-arid Texas High Plains. Irrigated winter wheat production in this region mainly depends on water from the Ogallala Aquifer. However declining water levels in this aquifer is a major concern for producers and policy makers. A modeling study was conducted using the DSSAT-CERES-Wheat model for accurate prediction of winter wheat grain and biomass yields and water use efficiency (WUE) responses to irrigation management in the Texas High Plains. Model calibration was performed using field observations of winter wheat response to nine irrigation treatments ranging from dryland to full irrigation. Close match of simulated crop phenology, grain and biomass yields, and evapotranspiration (ET) with observed data indicated accurate prediction of these parameters by the model. Results of simulations using historical weather data for 32 years (1980–2012) showed that a single irrigation of 100mm at jointing or booting had 35% higher grain yield than dryland while 140mm at anthesis or grain filling produced 68% higher grain yield compared to dryland. Simulation of biomass yield showed significant advantage of irrigating 100mm at jointing or booting stage compared to 140mm at anthesis or grain filling. Irrigation of 100mm at jointing and 140mm at anthesis (240mm in total) was found to produce similar grain and biomass yields as full irrigation (400mm). Deficit irrigation at grain filling significantly increased WUE compared to full irrigation. Advantage of deficit irrigation was more pronounced at seasons with below average precipitation. These results show the importance of irrigation timing in winter wheat production under water-limited conditions in the Texas High Plains.