Water repellence of a heavy textured Western Australian surface soil

Water repellence is shown to be a property of the heavy (20% clay) mallet hill soils found near Narrogin, W.A. The causes of the water repellence are examined, and the comminuted surface litter shown to be the major contributor. The water repellent soil could be made wettable by treatment with aqueous solvents, and water repellence could be restored by treating the wettable soil with non-polar solvents. A mechanism involving the coating of clay aggregates with hydrophobic litter to make the soil water repellent, and dispersion of the aggregates to make the soil wettable, is proposed. Spore-forming fungi do not cause water repellence and in some cases may reduce it. Water repellence is observed in artificial soil mixtures only when a litter component is present.