Soil electrical conductivity (ECa) by the four electrode method was studied in the laboratory as a function of soil water electrical conductivity (ECw) and water content in six soil types. A linear relationship between ECa and ECw 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 ECw to measured ECa. A method for calculating the partial contribution of surface conductance to ECa as a function of ECw and clay content is applied including a correction for dependence on the soil water content.
Soil electrical conductivity (ECa) by the four electrode method was studied in the laboratory as a function of soil water electrical conductivity (ECw) and water content in six soil types. A linear relationship between ECa and ECw 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 ECw to measured ECa. A method for calculating the partial contribution of surface conductance to ECa as a function of ECw and clay content is applied including a correction for dependence on the soil water content.