Soil moisture estimation based on the microwave scattering mechanism during different crop phenological periods in a winter wheat-producing region

In this research, a novel microwave scattering model-based semiempirical method for estimating the soil moisture of areas covered with winter wheat was proposed. In the proposed soil moisture estimation method, the crop and soil microwave scattering mechanisms during different crop phenological periods were considered to remove the influences of the wheat crop canopy on soil backscattering. Using RADARSAT-2 images and field-measured sample data, the validity and feasibility of the proposed soil moisture estimation method were verified in the study region of Hengshui City in the North China Plain. Among the winter wheat jointing stage, heading stage and maturity stage, the R-2, adjusted R-2 and RMSE values between the estimated soil moisture value and field-measured value were 0.762, 0.762 and 2.36%, respectively. The results indicate that high-accuracy soil moisture estimations could be obtained, and the proposed method had good performance in regional applications in the study region at key growth stages of winter wheat.