Effect of ionic strength and sodium adsorption ratio on the flocculation/dispersion of two surface soils from eastern Arkansas

Poor tilth and, often, a surface crust characterize eastern Arkansas soils. Such soils have very low water infiltration and high water runoff rate leading to increase turbidity in rivers and soil erosion. Sharkey clay and Desha silt loam soils from Delta region of eastern Arkansas were used to find the effect of sodium adsorption ratio (SAR) and ionic strength (IS) on the dispersion/flocculation behaviors of the soils. Percent light transmissions at a wavelength of 530 nm were related to the concentration of clay in suspension. Each soil was equilibrated with a series of solutions having different IS and containing Na+ and Ca2+ in various proportions. At different IS and SAR, the two soils exhibited different behaviors. Clay dispersibility was a more sensitive function of SAR at low IS than at high IS.