SOIL SALINITY AS AFFECTED BY HIGH-SULFATE WATER

Abstract

In a laboratory experiment, I investigated both salt buildup in three soils irrigated with various amounts of water high in sulfates and also the good-quality water needed for reclaiming such soils. Salt buildup followed in two distinct stages. The first stage was marked by a sharp increase in soil salinity as ions of both high and low solubility contributed to it. Salt buildup in the second stage was substantially slower and linearly related to the concentration of highly soluble ions. The SAR measured in soils taken from the pots at the end of salinization increased with every volume of sulfate water applied. There was initially also an increase in saturated hydraulic conductivity, followed thereafter by a sharp decrease. As with salt buildup the rate of leaching of salts followed two stages. First soluble salts were readily leached. Sharp decrease of both soil solution EC and SAR occurred at this stage. Thereafter, a steady state was reached, and decrease in soil solution EC was gradual and strongly dependent on gypsum dissolution.