Some physico-chemical properties of an exposed B horizon of a red-brown earth treated with gypsum

Abstract

Physico-chemical properties of a red-brown earth B horizon (Goulburn clay loam) were studied for three years following exposure and treatment with gypsum. In the first year irrigation and rain caused considerable leaching of soluble salts to 80 cm in both the control and gypsum treated plots. Gypsum was found to enhance the leaching of chloride by increasing the hydraulic conductivity in the upper soil profile. After three years soluble salts had returned to within 30 cm of the surface in the control plots, due to the occurrence of a perched water table. No similar increase occurred in the gypsum plots. Calcium-sodium exchange due to gypsum was slow to occur, and was mainly limited to the 0-10 cm layer. The exchange of calcium for magnesium was the dominant exchange reaction in this layer.