USDA soil taxonomy USDA soil taxonomy (ST) developed by the United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate classification of soil types according to several parameters (most commonly their properties) and in sev ...

, a Psamment is defined as an

Entisol Entisols are soils defined in USDA soil taxonomy that do not show any profile development other than an A horizon. An entisol has no diagnostic horizons, and most are basically unaltered from their parent material, which can be unconsolidated sedi ...

which consists basically of unconsolidated

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...

deposits,Unit 10: Terms (Psamment)
at pals.iastate.edu often found in shifting sand dunes but also in areas of very coarse- textured parent material subject to millions of years of weathering. This latter case is characteristic of the

Guiana Highlands The Guianas, sometimes called by the Spanish loan-word ''Guayanas'' (''Las Guayanas''), is a region in north-eastern South America which includes the following three territories: * French Guiana, an overseas department and region of France * ...

of northern South America. A Psamment has no distinct soil horizons, and must consist entirely of material of loamy sand or coarser in texture. 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 In ...

(WRB), Psamments are known as Arenosols. Psamments cover 3.4% of the global land mass. They occur throughout the world, being especially abundant in the deserts of

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

and

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

and on the ancient landforms of eastern

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

. Areas dominated by Psamments also occur in other humid regions, notably in

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

and

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwe ...

(the Sand Hills). Psamments typically have very low water-holding capacities because the sand in the soil is not ''graded'' so that sands of varying coarseness are constantly mixed right through the soil. Because most sands are highly siliceous, Psamments are also extremely low in all essential

nutrients A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excret ...

, most especially

phosphorus Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...

and are highly

acidic In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

in all except very arid climates. Psamments formed as a result of

glacial A glacial period (alternatively glacial or glaciation) is an interval of time (thousands of years) within an ice age that is marked by colder temperatures and glacier advances. Interglacials, on the other hand, are periods of warmer climate betw ...

erosion (common in

northern Europe The northern region of Europe has several definitions. A restrictive definition may describe Northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other g ...

) are typically of rather higher native fertility because of their youth, but are still much less fertile than most soils in the regions they are located in. The vegetation on Psamments varies enormously owing to the variety of climates, but in many cases is remarkably well-adapted to the climate, as with the ''

Fynbos Fynbos (; meaning fine plants) is a small belt of natural shrubland or heathland vegetation located in the Western Cape and Eastern Cape provinces of South Africa. This area is predominantly coastal and mountainous, with a Mediterranean clim ...

'' of the Cape region in

South Africa South Africa, officially the Republic of South Africa (RSA), is the southernmost country in Africa. It is bounded to the south by of coastline that stretch along the South Atlantic and Indian Oceans; to the north by the neighbouring countri ...

—famous for its remarkable

biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...

and the equally species-rich

Kwongan Kwongan is plant community found in south-western Western Australia. The name is a Bibbelmun (Noongar) Aboriginal term of wide geographical use defined by Beard (1976) as Kwongan has replaced other terms applied by European botanists such as ...

of southwestern

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

. The '' campinas'' and ''kerangas'' are healthy forests typical of Psamments in South America and

Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...

. Few Psamments are farmed, and where they are, the cost is high because of the expense of

fertilization Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proce ...

. They are always much less productive than other soils in the same region even when fertilized, and require careful management because the sand is very easily eroded. In USDA soil taxonomy, Psamments are divided into: * ''Cryopsamments:'' Psamments that have a cryic soil temperature regime * ''Quartzipsamments:'' other Psamments that have, in the 0.02 to 2.0 mm fraction within the particle-size control section, a total of more than 90 percent (by weighted average) resistant minerals * ''Torripsamments:'' other Psamments that have an aridic (or torric) moisture regime * ''Ustipsamments:'' other Psamments that have an

ustic Ustic is a class of soil moisture regime. It is one of a range of different soil moisture regimes, such as: aquic moisture regime, aridic moisture regime, udic moisture regime and xeric moisture regime. The ustic moisture regime is intermediate ...

moisture regime * ''Xeropsamments:'' other Psamments that have a xeric moisture regime * ''Udipsamments:'' other Psamments.

References

* Soil Survey Staff: Keys to Soil Taxonomy. 12th edition. Natural Resources Conservation Service. U.S. Department of Agriculture. Washington D.C., USA, 2014. * IUSS Working Group WRB: World Reference Base for Soil Resources, fourth edition. International Union of Soil Sciences, Vienna 2022.

.

External links

profile photos (with classification)
WRB homepage
profile photos (with classification)
IUSS World of Soils {{Soil type Pedology Types of soil

See also

References

Further reading

External links