Desiccation

Synonyms

Soil drying

Definition

The process in which wet soils dry and soil moisture content decreases as the moisture evaporates into the surrounding environment, leading ultimately to cracking of the ground surface.

During desiccation, the bulk water pressure within the soil pores will become negative with respect to the atmospheric pressure. This depression of pressure (i.e., the difference between atmospheric pressure and bulk water pressure) is known as the soil matric suction and is associated with the formation of curved water menisci within soil pores. On the basis of the capillary tube principle, the soil suction that can be sustained within a soil pore meniscus may be represented as 2Tcosθ/R, where T is the water surface tension, θ is the wetting angle, and Ris the radius of wetted part of soil pore. Therefore, the smaller the pore size, the higher the suction that can be sustained before soil becomes dry. Hence, clay soils tend to retain more moisture during drying than...