Influence of different organic wastes upon water retention, transmission and contact characteristics of a sandy soil

Abstract

Small cylinders were filled to a depth of 20 cm with Ludas sand to which different organic wastes, viz. sewage sludge, press mud, green manure and farmyard manure had been added up to a maximal rate equivalent to 827, 1043, 1370 and 542 t/ha. The cylinders were set in the ground and kept moist. At the end of 308 days' equilibration period, the samples were used for measuring soil water retention, saturated hydraulic conductivity as well as the horizontal infiltration with 0.01 M CaCl2 and alcohol. An apparent advancing contact angle was calculated from the last two measurements. The incorporation of all the organic wastes caused an appreciable increase in the amount of water retained at a given pressure potential. Increase in available water was caused by the application of sewage sludge and press mud only. Hydraulic conductivity, penetration coefficient and cumulative horizontal infiltration decreased markedly with additions of these materials. The maximum decrease in hydraulic conductivity was in case of press mud (93%), whereas the maximum decrease in penetration coefficient was in case of farmyard manure (81%). The contact angle, which plays an important role in penetration of water into porous materials, increased more in conventional organic manures (green manure and farmyard manure) than in municipal and industrial wastes (sewage sludge and press mud).