Influence of porosity and permeate suspended clay concentration on clay entrainment within a red ferrosol

Abstract

Soil pore size is an essential factor affecting pore blockage and subsequently saturated hydraulic conductivity (K sat). In this study we examined the effect of soil bulk density on suspend clay movement in a Red Ferrosol soil. Water with varying suspended clay concentrations (0, 5, 10 and 20 g L-1) was allowed to infiltrate cylindrical soil cores of a Red Ferrosol packed at two bulk densities (1.0 and 1.2 g cm-3). The Ksat was measured at both bulk densities and at all suspension concentrations. The outflow suspension concentration was measured as a function of pore volumes of drainage ~ 10 pore volumes. Following measurement, 2-cm long portions of undisturbed, drained soil cores were sampled from the top and bottom to measure water retention. Soil with low bulk density (1.0 g cm-3) allowed easier passage of suspended clay than the soil at high bulk density (1.2 g cm-3), even at a high suspension concentration (20 g L-1) with little occurrence of pore blockage. At both bulk densities, significant increases in water retention occurred near soil surface (top of soil core) than subsurface (bottom of soil core). This suggests that accumulation of clay sediment may have lead to pore blockage in the soil surface segments.