Functional Soil Mapping for Soil Moisture and Crop Yield Management in An Agricultural Landscape.

To advance hydropedological modeling and site-specific agriculture management, we need new ways of mapping soils for soil moisture and crop yield management in greater detail and with higher precision. In this study, integrated information of second-order soil map (SURGGO), soil properties, topography, and electromagnetic surveys was used to generate a refined soil map and a functional soil map. Significant differences (p<0.05) of soil apparent electrical conductivities among soil series can be observed in the electromagnetic surveys conducted in the winter and spring. In addition, the depth to bedrock varied significantly among soil series. Therefore, the differences of soil apparent electrical conductivities and depth to bedrock were utilized to generate the refined soil map. The accuracy of the refined soil map was validated with 70 soil cores collected in this field. Fifty-nine cores matched with the refined soil map, comparing with only 33 cores matched with the SURGGO map. After considering the purpose of managing soil moisture and grain yield, a functional soil map were generated by overlaying the refined soil map with the maps of depth to clay layer and surface texture since these two factors were significantly (p<0.05) correlated with the surface soil moisture and grain yields in this field. The spatial and temporal dynamics of surface soil moisture and grain yields were investigated among the major map units in the SURGGO and the functional soil maps. The latter one was much better in capturing the spatial variations of grain yield and soil moisture.