REGOSOL

one of the 30 soil groups in the classification system of the Food and Agriculture Organization (FAO). Regosols are characterized by shallow, medium- to fine-textured, unconsolidated parent material that may be of alluvial origin and by the lack of a significant soil horizon (layer) formation because of dry or cold climatic conditions. Regosols occur mainly in polar and desert regions, occupying about 2 percent of the continental land area on Earth, principally in northern China, Greenland, Antarctica, north-central Africa, the Middle East, and northwest Australia. They are usually found under their original natural vegetation or under limited dryland cropping. Regosols often show accumulations of calcium carbonate or gypsum in hot, dry climatic zones. In very cold climatic zones they contain permafrost within two metres (about six feet) of the land surface. Regosols are similar to the soils in the Entisol order of the U.S. Soil Taxonomy that occur in either very cold or very dry and hot climatic zones. They differ from the FAO soil groups Andosols, Arenosols, and Vertisols in parent materials, from Gleysols in having lower water content, and from Leptosols in having greater soil profile depth.