Water repellence in sandy soils of South-Western Australia. II. Some chemical characteristics of the hydrophobic skins

The hydrophobic organic skins on sand grains were resistant to removal by solvents such as cold water, concentrated acid, diethyl ether, ethanol, benzene, chloroform, and acetone. Prolonged treatment with hot diethyl ether, ethanol, and benzene removed part of the coating. Treatment with dilute solutions of alkali removed the skin as suspended particles. Compounds within the very stable humic fraction of the soil organic matter appeared to be mainly responsible for water repellence in soils. Deposits of fresh organic materials could also produce water repellent properties.