Creating Hydrophobic Soil for Water Harvesting

Investigations were conducted to determine the feasibility of increasing precipitation runoff from soil surfaces by spraying them with chemicals that cause the soil to become hydrophobic. Five different types of chemicals were evaluated and their performance characteristics are described. One chemical proved suitable for field application and produced 94% runoff from a field plot of sandy loam soil for 5 months after application. Runoff from a 0.04-in. rain falling on dry soil was 60%. Erosion of the hydrophobic soil surface reduced runoff to 76% during the following year. Results indicate that water-repellent chemicals, in combination with soil stabilizers, have potential value for the construction of efficient, low-cost harvesting catchments.