Characteristics and Genesis of Some Sodic Soils in the Indo-Gangetic Alluvial Plains of Haryana and Uttar Pradesh

Sodic soils in the slates of Haryana and Uttar Pradesh forming a pert of the Indo-Gangetic alluvial plain begin to appear on the soilscape surfaces of the Pleistocene age. These soils generally occupy micro depressions of about 20 to 30 cm depth. Release of salts in the Siwalik/piedmont zone and the plains through alkali hydrolysis during the weathering of aluminosilicate minerals and their repeated convergence into micro-depressions lead to the genesis of these sodic soils at the surface, where good quality ground water occur in the substratum. Sodic environment favours degradation of aluminosilicate minerals resulting in accumulation of amorphous silica, alumina, potassium and iron. Degradation is maximum at the surface and decreases with depth as does the degree of sodicity. Weathering of mica present in these soils yields finer constituents of clay which preferentially move downwards in highly deflocculated form and give rise to an illuvial B horizon.