New Calibrations for Determining Soil Electrical Conductivity—Depth Relations from Electromagnetic Measurements

Soil salinity can be determined in the field from measurements of soil electrical conductivity (EC a ). Measurements of depth‐integrated EC a can be made remotely using electromagnetic induction (EM) techniques. A means of determining EC a for the soil depth intervals of 0 to 30, 30 to 60, 60 to 90 cm, etc., from the EM measurements is needed for salinity appraisal. The EM and EC a measurements were made at about 900 sites in the San Joaquin Valley of California. This large data set was used, along with rigorous statistical techniques, to obtain empirical coefficients used in equations to predict EC a by depth intervals within the soil profile from EM readings taken above ground. Predictions were found to be more accurate using these new coefficients rather than those previously available.