FIELD STUDIES ON SALT LEACHING IN A HIGHLY SALINE SODIC SOIL

Abstract

The effect of continuous and intermittently ponded water, with or without the application of gypsum, was studied on the leaching (redistribution) of salts in a highly saline sodic soil. Field plots measured 8 m x 11 m and were replicated four times. The results of 42 days' leaching tests showed that whereas gypsum greatly enhanced leaching of salts, intermittent ponding had no particular advantage over continuous ponding treatments. This is ascribed to the low permeability of sodic soils resulting in water movement in unsaturated conditions even in continuously ponded treatments. Apart from increased depth of salt leaching in gypsum-treated plots, the salts underwent considerable dispersion and were distributed in a greater soil depth. This resulted from changes in the pore size distribution and resulting velocity distribution within the water flowing through soil pores. The effect of continuous and intermittently ponded water, with or without the application of gypsum, was studied on the leaching (redistribution) of salts in a highly saline sodic soil. Field plots measured 8 m x 11 m and were replicated four times. The results of 42 days' leaching tests showed that whereas gypsum greatly enhanced leaching of salts, intermittent ponding had no particular advantage over continuous ponding treatments. This is ascribed to the low permeability of sodic soils resulting in water movement in unsaturated conditions even in continuously ponded treatments. Apart from increased depth of salt leaching in gypsum-treated plots, the salts underwent considerable dispersion and were distributed in a greater soil depth. This resulted from changes in the pore size distribution and resulting velocity distribution within the water flowing through soil pores. © Williams & Wilkins 1973. All Rights Reserved.