Calcids are a soil suborder in the USDA soil taxonomy. They are aridisols that have accumulated high levels of residual or dryfall calcium carbonate.
Background
Calcids have a calcic or petrocalcic horizon and have carbonated materials in any above layers. The parent materials are high in content of carbonate, or carbonates were added as dust, or both. Precipitation has been insufficient to remove the carbonates or even move them to great depths. These soils are often found in the western states of North America. Most areas are used as rangeland or wildlife habitat. Some are used as irrigated cropland.
Aridisols are CaCO3 containing soils of arid regions that exhibit at least some sub-surface horizon development. They are characterized by being dry most of the year and exhibit limited leaching. Aridisols contain sub-surface horizon in which clays, calcium carbonate, silica, salts, and CaCO3 tend to be leached from soils of moister climates. Land dominated by Aridisols are used mainly for range, wildlife, and recreation. Because of the dry climate in which they are found, they are not used for agricultural production unless irrigation water is available. Aridisols are divided into seven suborders: Cryids, Salids, Durids, Gypsids, Argids, Calcids, and Cambids.