Ultisol

Ultisol, commonly known as red clay soil, is one of twelve soil orders in the United States Department of Agriculture soil taxonomy. The word "Ultisol" is derived from "ultimate", because Ultisols were seen as the ultimate product of continuous weathering of minerals in a humid, temperate climate without new soil formation via glaciation. They are defined as mineral soils which contain no calcareous (calcium carbonate containing) material anywhere within the soil, have less than 10% weatherable minerals in the extreme top layer of soil, and have less than 35% base saturation throughout the soil. Ultisols occur in humid temperate or tropical regions. While the term is usually applied to the red clay soils of the Southern United States, Ultisols are also found in regions of Africa, Asia, Australia and South America. In the World Reference Base for Soil Resources (WRB), most Ultisols are known as Acrisols and Alisols. Some belong to the Retisols or to the Nitisols. Aquults are typically Stagnosols or Planosols. Humults may be Umbrisols.

Ultisol, commonly known as red clay soil, is one of twelve soil orders in the United States Department of Agriculture soil taxonomy. The word "Ultisol" is derived from "ultimate", because Ultisols were seen as the ultimate product of continuous weathering of minerals in a humid, temperate climate without new soil formation via glaciation. They are defined as mineral soils which contain no calcareous (calcium carbonate containing) material anywhere within the soil, have less than 10% weatherable minerals in the extreme top layer of soil, and have less than 35% base saturation throughout the soil. Ultisols occur in humid temperate or tropical regions. While the term is usually applied to the red clay soils of the Southern United States, Ultisols are also found in regions of Africa, Asia, Australia and South America. In the World Reference Base for Soil Resources (WRB), most Ultisols are known as Acrisols and Alisols. Some belong to the Retisols or to the Nitisols. Aquults are typically Stagnosols or Planosols. Humults may be Umbrisols. File:Nc-red-clay-soil-2.jpg|Red clay soil is common throughout the Southern United States, especially around the Piedmont. This photo was taken in North Carolina. File:Ultisol-map-1.jpg|Map showing distribution and types of Ultisols throughout the United States; there is no Ultisol on the Ohio River flood plains, as the river has historically deposited other soil types there during its regular natural flooding. File:Ultisol-map-2.gif|Map of the United States showing what percentage of the soil in a given area is classified as an Ultisol-type soil. The great majority of the land area classified in the highest category (75%-or-greater Ultisol) lies in the South and overlays with the Piedmont Plateau, which runs as a diagonal line through the South from southeast (in Alabama) to northwest (up into parts of Maryland). UltisolWorld.jpg|Utlisols of the world ==Suborders== Aquults: Ultisols with a water table at or near the surface for much of the year Humults: well-drained Ultisols that have high organic matter content Udults: Ultisols of humid climates Ustults: Ultisols of semiarid and subhumid climates Xerults: temperate Ultisols with arid summers and moist winters ==See also== Soil formation Pedology Soil classification Red soil Kurosol ==References==

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