A study of water repellency and its amelioration in a yellow-brown sand

Abstract

Water repellency of Himatangi sand was assessed by in situ water infiltration measurements and in the laboratory using the Molarity of an Ethanol Droplet (MED) technique. Infiltration rates on water repellent areas were an order of magnitude lower than rates on adjacent, less repellent areas. The surface (30mm) soil of cores removed from repellent areas was severely repellent(MED > 2.2), and soil to a depth of 150mm was moderately repellent. MED was strongly correlated with soil carbon content (R 2 =0.79). Attempts were made to overcome repellency by wetting the soil and by abrasion. The water repellency of Himatangi sand increased when the gravimetric soil water content, w, was increased from 0.03 to 0.05, and then declined rapidly with further increases in soil water content. Air-dry samples were agitated in an end-over-end shaker for a range of 1-48 h. Soil water repellency was significantly (P < 0.01)reduced by agitation for up to 8 h. Warter repellency of samples which had been shaken for 2,...