Coupled Transport of Aqueous Potassium Chloride and Potassium Sulphate in some Alfisols, Entisol and Inceptisol

Coupled osmotic transport processes involving passages of aqueous electrolytes KCl and K₂SO₄ in four soils of West Bengal possessing contrasting physicochemical properties have been studied. The experimental data have been fitted to formulations based on irreversible thermodynamics to yield the appropriate reflection coefficient (σ), mechanical filtration capacity (L_p) and solute permeability (ω) for various transport systems. The hydrodynamic frictional coefficients (f) have also been determined for the osmotic flow through the given soils. The values of σ and L_p for the given soils were found to be related, respectively, directly and inversely with the clay content of the present soils. These results are in agreement with the high ionic sorption capacity of the clays, particularly in the soils rich in illitic clays which are known to possess specific sites for K⁺ ions. The relative values of the frictional coefficients between solute, solvent and the soil plug have also provided valuable information on decoupling of solute and solvent in course of the present osmotic transport processes, leading to solute accumulation in the soils, relatively rich in illitic clays.