Abstract
A multi-frequency electromagnetic sounding system (MFEM) enables non-destructive and instanta-neous measurements of soil electrical conductivity (EC) profiles. Because agricultural and forest lands are possi-ble sources of pollutant loads transported to aquatic envi-ronments, we applied MFEM to develop a procedure for conducting efficient soil environmental surveys for evalu-ation of management practices on forested lands. We in-vestigated two types of forested sites: thinning sites (TS) and delayed thinning sites (DTS). The MFEM-EC data col-lected from surface soils were well correlated with the EC data collected by a conventional sensor. MFEM-EC map-ping revealed higher EC values in surface soils of DTS. Delayed thinning had reduced understory vegetation and hydraulic conductivity of surface soils. Therefore, low plant uptake and shallow infiltration of soluble salts would have allowed them to remain in the surface soils of DTS. Forest sites that had been fertilized as farmlands could also be distinguished with an MFEM system. The proposed MFEM system would be a useful tool for creening sur-veys of forested sites prior to detailed analysis of a wider area.
