The Dynamic Process and Model Simulation of Soil Moisture in Wheat Growth Period

PurposeThe soil moisture status in the field is the basis of irrigation management, and the dynamic process of soil moisture is an important basis for irrigation forecasting.

MethodBy monitoring the soil moisture at different depths and meteorological data during the growth period of winter wheat, the dynamic process of soil moisture in the field of wheat growth and its response to precipitation and crop water requirement were analyzed, and the soil water balance model was used to simulate the change process of soil moisture.

ResultDuring the whole growth period of wheat, the soil moisture of each layer in the main active layer (0-50 cm) was between 12.00% and 34.53%, and the variance was between 5.74 and 34.05. The soil moisture of 20 cm was the best correlation with the soil moisture of the main active layer (0-50 cm) of winter wheat, and the correlation coefficient was 0.96%. The response of soil moisture at 20 and 40 cm depth to precipitation and crop water requirement had a 12-hour lag. Light and moderate drought occurred in winter wheat fields after jointing stage. In the tenth scale, the maximum simulation error of the soil water balance model was less than 10%.

ConclusionUnder the influence of precipitation and crop water requirement, soil depth had an effect on the change process of soil moisture, and the effect decreases with the increase of depth. The soil moisture at 20 cm depth was the closest to the change process of soil moisture in the main active layer of the root system, which can be used as the representative depth of soil moisture monitoring. In the P=25% hydrological year, supplementary irrigation is needed for winter wheat fields. The water balance model with less than one-tenth time scale can well simulate the dynamic process of soil moisture.