Salt effect on hydraulic conductivity of a vertisol

Abstract

Summary The changes in saturated hydraulic conductivity, macroscopic swelling and clay dispersivity of a sodic black clay soil (Fine, montmorillonitic hyperthermic family of typic chromusterts) in relation to solution concentration (⩽800 me/l) and Na adsoprtion ratio (⩽50(me/l) 1/2 ) of the percolating solution were measured. Based on the threshold concentration curves, an empirical relationship relating saturated hydraulic conductivity and soil solution properties has been derived for Vertisols and its field applicability established. Although solution dispersible clay increased with SAR, the solution concentration of 10 me/l or more counteracted the dispersion of clay particles. Swelling increased almost linearly with solution SAR but registered a steep decline with increase in cation concentration of the solution upto 350 me/l. For all practical purposes, swelling of clay seemed to be the major factor responsible for loss of saturated hydraulic conductivity of a sodic Vertisol.