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Orthent



 
 
In USDA soil taxonomy
USDA soil taxonomy

USDA Soil Taxonomy developed by United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate Soil classification of soil types according to several parameters and in several levels: Order, Suborder, Great Group, Subgroup, Family, and Soil series....
, Orthents are defined as Entisols that lack horizon development due to either steep slopes or parent materials that contain no permanent weatherable minerals (such as ironstone
Ironstone

Ironstone is a fine-grained, heavy and compact sedimentary rock. Its main components are the carbonate or oxide of iron, clay and/or sand. It can be thought of as a concretionary form of siderite....
). Typically, Orthents are exceedingly shallow soils. They are often referred to as "skeletal soils" or, in the FAO soil classification
FAO soil classification

The Food and Agriculture Organization of the United Nations developed a supra-national classification, also called World Soil Classification, which offers useful generalizations about soils pedogenesis in relation to the interactions with the main soil-forming factors....
, as Lithosols. The basic requirement for recognition of an orthent is that any former soil
Soil

Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface. Soil is composed of particles of broken rock that have been altered by chemical and environmental processes including weathering and erosion....
 has been either completely removed or so truncated that the diagnostic horizons typical of all orders other than Entisols are absent.

Most Orthents are found in very steep, mountainous regions where erodible material is so rapidly removed by erosion that a permanent covering of deep soil cannot establish itself.






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In USDA soil taxonomy
USDA soil taxonomy

USDA Soil Taxonomy developed by United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate Soil classification of soil types according to several parameters and in several levels: Order, Suborder, Great Group, Subgroup, Family, and Soil series....
, Orthents are defined as Entisols that lack horizon development due to either steep slopes or parent materials that contain no permanent weatherable minerals (such as ironstone
Ironstone

Ironstone is a fine-grained, heavy and compact sedimentary rock. Its main components are the carbonate or oxide of iron, clay and/or sand. It can be thought of as a concretionary form of siderite....
). Typically, Orthents are exceedingly shallow soils. They are often referred to as "skeletal soils" or, in the FAO soil classification
FAO soil classification

The Food and Agriculture Organization of the United Nations developed a supra-national classification, also called World Soil Classification, which offers useful generalizations about soils pedogenesis in relation to the interactions with the main soil-forming factors....
, as Lithosols. The basic requirement for recognition of an orthent is that any former soil
Soil

Soil is the naturally occurring, unconsolidated or loose covering on the Earth's surface. Soil is composed of particles of broken rock that have been altered by chemical and environmental processes including weathering and erosion....
 has been either completely removed or so truncated that the diagnostic horizons typical of all orders other than Entisols are absent.

Most Orthents are found in very steep, mountainous regions where erodible material is so rapidly removed by erosion that a permanent covering of deep soil cannot establish itself. Such conditions occur in almost all regions of the world where steep slopes are prevalent. In Australia
Australia

Australia, officially the Commonwealth of Australia, is a country in the southern hemisphere comprising the Australia of the world's smallest continent, the major island of Tasmania, and numerous list of islands of Australia in the Indian Ocean and Pacific Oceans....
 and a few regions of Africa
Africa

Africa is the world's second-largest and second most-populous continent, after Asia. At about 30.2 million km? including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area....
, Orthents occur in flat terrain because the parent rock contains absolutely no weatherable minerals except short-lived additions from rainfall, so that there is no breaking down of the minerals (chiefly iron
Iron

Iron is a chemical element with the symbol Fe and atomic number 26. Iron is a Group 8 element and period 4 element. Iron is lustrous and silvery in color....
 oxides) in the rock.

The steepness of most Orthents causes the flora on them to be sparse shrubs or grassland
Grassland

Grasslands are areas where the vegetation is dominated by grasses and other herbaceous plants . However, sedge and rush families can also be found....
. In those on ancient, flat terrain, dry grassland, savanna
Savanna

A savanna, or savannah, is a tropical, subtropical or temperate woodland ecosystem characterized by the trees being sufficiently small or widely spaced so that the Canopy does not close....
, or, very rarely, rainforest
Rainforest

Rainforests are forests characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1750?2000 mm . The monsoon trough, alternately known as the intertropical convergence zone, plays a significant role in creating Earth's tropical rain forests....
 can prevail.

Because of their extreme shallowness and, usually, steepness and consequent high erosion hazard, Orthents are not suitable for arable farming. The flora typically supported on them is generally of very poor nutritive value for grazing, so that typically only low stocking rates are practicable. Many Orthents are very important as habitat for wildlife.

See also

  • Pedogenesis
    Pedogenesis

    Pedogenesis or soil evolution is the process by which soil is created. It is the major topic of the science of pedology , whose other aspects include the soil morphology, soil classification of soils, and their distribution in nature, present and past ....
  • Pedology (soil study)
    Pedology (soil study)

    Pedology is the study of soils in their natural environment. It is one of two main branches of soil science, the other being edaphology. Pedology deals with pedogenesis, soil morphology, and soil classification, while edaphology studies the way soils influence plants, fungi, and other living things....
  • Soil classification
    Soil classification

    Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use....