Soil Moisture and Crop Evapotranspiration Forecast for Winter Wheat Based on Weather Information in North China Plain

Soil moisture and crop evapotranspiration (ETc) forecast based on weather information is a basis for realizing precise irrigation, which could be an innovative technique for water-saving strategy in irrigated district. Combined with longterm experimental data in People's Victory Canal irrigated district, we put forward a systematic soil moisture forecast method for winter wheat using related weather information. In this study, hourly soil moisture was automatically monitored by a soil moisture monitoring system. Weather information for the following two weeks was automatically acquired. Combined with ETc, soil moisture forecast can be used to predict irrigation time and amount which differs among growth stages of winter wheat. In particular, irrigation time can be decided by monitoring soil moisture when reaching to lower limit of soil moisture for winter wheat, and the irrigation amount can be determined by calculating soil water storage needed to meet planned wetting layer according to crop growth monitoring. Parameters in soil moisture and crop evapotranspiration forecast models were determined using Levenberg-Marquardt regression. Validation test suggests that the models we developed are reliable. We conclude that the models can serve as a useful tool for future irrigation forecast.