Orthents are
soils defined in
USDA soil taxonomy as
entisols that lack due to either steep slopes or parent materials that contain no permanent weatherable
minerals (such as
ironstone).
Typically, Orthents are exceedingly shallow soils. They are often referred to as ''skeletal soils'' or, in the United Nations
FAO soil classification The Food and Agriculture Organization of the United Nations (FAO) developed a supra-national classification, which offers useful generalizations about pedogenesis in relation to the interactions between the main soil-forming factors. It was first pu ...
, as ''lithosols''.
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.
Characteristics
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, 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 a few regions of
Africa, 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 oxides) in the rock.
The steepness of most orthents causes the
flora on them to be sparse shrubs or
grassland. In those on ancient, flat terrain, dry grassland,
savanna, or rarely,
rainforest
Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...
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
livestock stocking rates are practicable. Many orthents are very important as habitat for wildlife.
See also
*
Pedogenesis
*
Pedology
*
Soil classification
References
*
tp://ftp-fc.sc.egov.usda.gov/NSSC/Soil_Taxonomy/tax.pdfv Soil Taxonomy p420{Dead link, date=April 2020 , bot=InternetArchiveBot , fix-attempted=yes
New Zealand Journal of ScienceFundamentals of Soils By John Gerrard
Pedology
Types of soil