The effect of texture stratification on salt accumulation in an arid land soil

Abstract

A laboratory soil-column experiment was conducted to study the effect of soil stratification on salt distribution in soil profiles under fallow condition. Columns (6.3 cm ID. x 55 cm) of homogeneous and stratified Pima clay loam and Pima sandy loam were used. The stratifications consisted of 1 and 5 cm thick layers, 10 cm below the surface. Salty groundwater containing a total of 5,000 ppm of the ions Na, Ca, Mg, Cl, and SO ₄ was maintained at 55 cm below the soil surface of each column. Observation of capillary rise and evaporation were made daily. Chemical analyses of the soil for the selected depths were carried out after 32 days. In general, the column surfaces of the stratified soils were significantly higher in salt than the homogeneous sand and clay soils, due to the upward movement of the salty groundwater through the soil columns which finally evaporated at or near the surface. The major ions contributing to the surface salts were Na⁺, Ca⁺⁺, and Cl⁻. Furthermore, salt in clay soil columns was relatively higher in Ca⁺⁺ concentration and lower in levels of Na⁺ than in the sandy soil.