Aridisols (or desert soils) are a soil order in
USDA soil taxonomy
USDA soil taxonomy (ST) developed by the United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate Soil classification, classification of soil types according to several parameters (most commonly their p ...
. Aridisols (from the Latin ''aridus'', for "dry", and ''solum'') form in an arid or semi-arid climate. Aridisols dominate the
deserts and xeric shrublands
Deserts and xeric shrublands are a biome defined by the World Wide Fund for Nature. Deserts and xeric (Ancient Greek 'dry') shrublands form the largest terrestrial biome, covering 19% of Earth's land surface area. Ecoregions in this habitat ...
, which occupy about one-third of the Earth's land surface. Aridisols have a very low concentration of
organic matter
Organic matter, organic material or natural organic matter is the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have come fro ...
, reflecting the paucity of vegetative production on these dry soils.
Water deficiency is the central defining characteristic of Aridisols. Also required is sufficient age to exhibit
subsoil
Subsoil is the layer of soil under the topsoil on the surface of the ground. Like topsoil, it is composed of a variable mixture of small particles such as sand, silt and clay, but with a much lower percentage of organic matter and humus. The su ...
weathering and development. Limited leaching in aridisols often results in one or more subsurface soil horizons in which suspended or dissolved minerals have been deposited: silicate clays, sodium, calcium carbonate, gypsum, or soluble salts. These subsoil horizons can also be
cemented by carbonates, gypsum, or silica. Accumulation of salts on the surface can result in
salinization.
In the
World Reference Base for Soil Resources
The World Reference Base for Soil Resources (WRB) is an international soil classification system for naming soils and creating legends for soil maps. The currently valid version is the fourth edition 2022. It is edited by a working group of the I ...
(WRB), most Aridisols belong to the
Calcisols,
Gypsisols,
Durisols and
Solonchaks.
steppe
In physical geography, a steppe () is an ecoregion characterized by grassland plains without closed forests except near rivers and lakes.
Steppe biomes may include:
* the montane grasslands and shrublands biome
* the tropical and subtropica ...
passes into the semi-desert, such as in the lower Volga
The Volga (, ) is the longest river in Europe and the longest endorheic basin river in the world. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catchment ...
region
See also
*
Desert ecology
*
Pedogenesis
Soil formation, also known as pedogenesis, is the process of soil genesis as regulated by the effects of place, environment, and history. Biogeochemical processes act to both create and destroy order (anisotropy) within soils. These alterations ...
*
Pedology
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Soil classification
*
Soil science
Soil science is the study of soil as a natural resource on the surface of the Earth including soil formation, soil classification, classification and Soil survey, mapping; Soil physics, physical, Soil chemistry, chemical, Soil biology, biologica ...
*
Soil type
A soil type is a taxonomic unit in soil science. All soils that share a certain set of well-defined properties form a distinctive soil type. Soil type is a technical term of soil classification, the science that deals with the systematic categ ...
*
Calcid
References
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{{Soil type
Pedology
Types of soil