Hydrophobic soils repel water. A thin layer of soil at or below the mineral soil surface can become hydrophobic after intense heating. The hydrophobic layer is the result of a waxy substance derived from plant material burned during a hot fire. The waxy substance penetrates into the soil as a gas and solidifies after it cools, forming a waxy coating around soil particles. Not all fires produce a water- repellent layer in soil.
Hydrophobicity reduces the amount of water infiltration resulting in increased runoff.
You can download and copy this sheet and provide it to homeowners in burned areas. Printed copies of this Soil Quality Information Sheet are not yet available. North Dakota State University professors have requested copies of the primer for use in soil microbiology courses. Seed company representatives are using illustrations from the primer in their presentations. A seed dealer informed NRCS that his company is willing to pay for the printing cost of 5,000 copies of the primer.