FINGER-LIKE WETTING PATTERNS IN 2 WATER-REPELLENT LOAM SOILS

In soils with fingered flow, surface-applied solutes can reach the groundwater more rapidly than in the case of homogeneous wetting. So far, fingered flow has been thought to be restricted to fine over coarse-textured soils and homogeneous sandy soils. The present study was undertaken to demonstrate the occurrence of fingerlike wetting patterns in a silt loam and in a silty clay loam soil, and to investigate the influence of dry bulk density and water repellency on the observed soil moisture patterns. Fingerlike patterns were photographed and soil water contents determined by intensive soil core sampling. In both soils, dry bulk density was not a main factor in inducing wet fingerlike patterns and high water content variability. The degree and persistence of potential water repellency were measured on soil samples using the alcohol percentage test and the water drop penetration time (WDPT) test. Spatial variability of degree and persistence of potential water repellency and, accordingly, of soil water contents were high. The actual water repellency was measured on field-moist samples to obtain critical soil water content values. The soil is wettable above and water-repellent below these values.