SPECIFIC EFFECT OF MAGNESIUM ON THE HYDRAULIC CONDUCTIVITY OF SODIC SOILS

Abstract

Summary Exchangeable Mg does not have a specific effect on the hydraulic conductivity (HC) and clay dispersion in calcareous soils. Conversely, in well‐weathered soils, which do not contain CaCO 3 , a specific effect of exchangeable Mg is evident, on both HC losses and clay dispersion, when the Na/Mg soils are leached with distilled water (simulating rain water). Soil clays, when Mg‐saturated, are chemically more stable and do not release electrolytes into the solutions: they thus disperse more easily when leached with distilled water. The presence of exchangeable Mg enhances the dissolution of CaCO 3 in calcareous soils, and the electrolytes prevent the dispersion of the clay and HC losses in the Na/Mg calcareous soils.