The effect of lime and vegetation management on non-wetting behaviour of an acid siliceous sand

Abstract

Water repellence was measured on a moderately water repellent, acid, siliceous sand to which 4 rates (0, 1, 2, 4t ha-1) of lime had been applied. The trial plots were split with half growing subterranean clover and half kept bare of all vegetation. Water repellence of the soil was measured using small ring infiltrometers in situ, and the molarity of ethanol drop (MED) test in the lab. The soil bulk d. of each plot was also measured. The results showed that water infiltration rate into the soil was not significantly affected by lime rate; however, significant and large differences occurred between vegetated and nonvegetated plots. Infiltration rate was approx. four times greater in nonvegetated plots than plots with subterranean clover growing on them, irresp. of lime rate. There was no significant effect of lime rate or vegetation on soil bulk d. When the water repellence of the vegetated treatments was measured by the MED test, lime rates up to 2 t ha-1 were assocd. with increased water repellence. At 4 t ha-1 lime, MFD (20.degree.) was decreased slightly. Differences in MED (20.degree.) between lime rates in the plots with no plant cover were not significant. Lime applied to acid, water repellent sandy soils at rates up to 4 t ha-1 did not reduce water repellence. Care must be taken when comparing different methods of measuring water repellence, as there was poor correlation between MED and infiltration rate. Presence of vegetation severely reduces water infiltration into acid, water repellent, siliceous sands.