Effect of Anion Exclusion on the Movement of Chloride through Soils

The effects of anion exclusion on the movement of chloride (Cl ‐ ) through soils was studied using a variety of subsurface soil samples from southern California. The data reported, suggest that the nature of the clay mineral, clay content, saturation percentage and iron oxide content together with the cation‐exchange capacity are important soil characteristics related to the volume of exclusion. General equations that are based only on specific charge, seem to be oversimplifications. Another serious limitation of general equations obtained under laboratory conditions is their extrapolation to field conditions. The high variability regarding salt distribution commonly found in the field, makes the use of correction factors, such as volume of exclusion, of limited value. More studies under field conditions are necessary before quantitative predictions can be made using general equations obtained with disturbed soil samples in the laboratory.