An assessment of irrigation practices: Sprinkler irrigation of winter wheat in the North China Plain

Winter wheat production in the North China Plain (NCP) relies mainly on irrigation. To assess the effect irrigation management practices on crop production, the HYDRUS-1D model was modified by incorporating the crop growth module adopted from the EPIC model. The modified HYDRUS-1D model was calibrated and validated by using data collected from 2006/2007 and 2007/2008 winter wheat growing seasons in Beijing area. The predicted values for soil water content, soil nitrate concentration, crop growth, yield, and evapotranspiration showed good agreements with the measured values. The calibrated model was then used to evaluate the yield and water use efficiency (WUE) under different hydrologic years. The WUE for different irrigation depth was considered as the criterion for investigating the appropriate irrigation management practices. Results showed that the appropriate irrigation depth per application could be determined as 62.5% of the difference between 20 cmpan evaporation and precipitation for hydrologic years with 75%, 50% and 25% probability of rainfall occurrence, respectively, under the recommended nitrogen application rate in Beijing area. And the corresponding total irrigation amount was 244.7, 213.8 and 192.5 mm. The results of this study provide scientific implications for water management of winter wheat under sprinkler irrigation in the NCP and those areas with similar climatic and cropping practice conditions.