Soil Moisture Retrieval over Soybean Fields Using Passive Microwave Data

As a crucial crop for oil and protein, soybean is highly sensitive to soil moisture during growth. Therefore, it is crucial to accurately monitor soil moisture over soybean fields during the growth period. In the L-band Microwave Emission of the Biosphere (L-MEB) model, the calculation of vegetation transmissivity may have some limitations, potentially affecting soil moisture retrieval accuracy. To improve the effectiveness of the retrieval, we introduced the improved Beer-Lambert law to describe the attenuation effect of the vegetation layer on the microwave signals more accurately, thus improving the L-MEB model. The experimental results indicate that our improved method significantly enhances the accuracy of soil moisture retrieval over soybean fields: the correlation coefficients of soil moisture results retrieved using vegetation water content and leaf area index improved by 0.9% and 9.5%, respectively, and the root mean square errors decreased by 39.78% and 19.35%, respectively.