Determination of Soil Solution Electrical Conductivity from Bulk Soil Electrical Conductivity Measurements by the Four‐Electrode Method

Soil electrical conductivity (EC a ) by the four electrode method was studied in the laboratory as a function of soil water electrical conductivity (EC w ) and water content in six soil types. A linear relationship between EC a and EC w was valid only at salinities > 4 mmho/cm. At very low salinity levels the contribution of the surface conductance was not constant and had a higher contribution than EC w to measured EC a . A method for calculating the partial contribution of surface conductance to EC a as a function of EC w and clay content is applied including a correction for dependence on the soil water content.