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Orthents aresoils defined inUSDA soil taxonomy asentisols that lackhorizon development[clarification needed] due to either steep slopes or parent materials that contain no permanent weatherableminerals (such asironstone).
Typically, Orthents are exceedingly shallow soils. They are often referred to asskeletal soils or, in the United NationsFAO soil classification, aslithosols.
The basic requirement for recognition of an orthent is that any former soil has been either completely removed or so truncated that characteristics 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.
InAustralia and a few regions ofAfrica, orthents occur in flat terrain because the parent rock containsabsolutely no weatherable minerals except short-lived additions from rainfall, so that there is no breaking down of the minerals (chieflyiron oxides) in the rock.
The steepness of most orthents causes theflora on them to be sparse shrubs orgrassland. In those on ancient, flat terrain, dry grassland,savanna, or rarely,rainforest 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 lowlivestock stocking rates are practicable. Many orthents are very important as habitat for wildlife.
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