The Use of Soil Electrical Conductivity to Investigate Soil Homogeneity in Story County, Iowa, USA

Precision agriculture, environmental applications, and land use planning needs have led to demands for more detailed soil maps. A remote sensing technique that can differentiate soils with a high degree of accuracy would be ideal for soil survey purposes. One technique that has shown promise in Iowa is electrical conductivity (EC a ) measured by the Geonics EM‐38. Electrical conductivity readings obtained with this technique integrate the soils’ water content, clay content, soluble salt content, and temperature. One way EC a techniques have been evaluated as soil survey tools involves grid mapping a field, performing an EC a survey, and then comparing maps obtained using each method. Good results have been obtained in this way for several fields in central Iowa that contain soils that are quite variable over relatively short distances. However, these fields had heterogeneous soil properties. There is a need to investigate the application of EC a techniques in fields with more homogenous soil properties. Therefore, a field with lacustrine‐derived soils that exhibits only slight spatial variability in soil properties was chosen for this study. Consequently, highly uniform EC a readings were obtained, and it was not possible to differentiate soil map units (SMUs) using the EC a data. However, the results did confirm the uniform nature of the soils in the field, a critical criterion for precision agriculture applications.