Influence of leaching with different amounts of water on desalinization and permeability behaviour of chloride and sulphate-dominated saline soils

Abstract

Desalinization studies were carried out in Cl-dominated (Cl:S0 4 = 7:3) and SO 4-dominated (Cl:S0 4 = 3:7), saline (ECe = 9 dS m −1, ESP = 10) sandy loam soils, filled in plexiglass columns up to a height of 60 cm at uniform bulk density. Both soils were subjected to leaching with three amounts, i.e. 20, 40 and 60 cm of distilled water, 5 cm at a time until the three leaching cycles were completed. The S0 4 profiles had 20–75% faster percolation than their Cl counterparts, when 40 cm of water was leached. With higher amounts of leaching water, the differences in permeability between the two soils narrowed and became indistinguishable when 60 cm of water was leached. Desalinization of the Cl-profiles was more efficient than the S0 4-profiles, but the reverse was the case with desodification. When the depth of water (dW) leached was less than or equal to the depth of soil WS), desalinization was less efficient (10–25%) under S0 4 than under Cl-salinity. However, when dW was greater than dS, the differences in the magnitude of leaching of salts under the two salinities narrowed and became equal at a dW/dS ratio of 2. An increase in the soil ESP from 10 to 35 resulted in a 75% decrease in soil permeability under Cl compared with a 64% decrease in S0 4-salinity. At ESP of 10, application of farmyard manure (FYM) as an amendment increased soil permeability for both Cl- and S0 4-dominated soils. However, at higher ESP levels (30–35), FYM application decreased soil permeability under Cl-dominated soil, but increased it under S0 4-dominated soil.