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A taxonomy is an arrangement in a systematic manner; the USDA soil taxonomy has six levels of classification. They are, from most general to specific: order, suborder, great group, subgroup, family and series. Soil properties that can be measured quantitatively are used in this classification system – they include: depth, moisture ...
USDA soil taxonomy provides the core criteria for differentiating soil map units. This is a substantial revision of the 1938 USDA soil taxonomy which was a strictly natural system. The USDA classification was originally developed by Guy Donald Smith , director of the U.S. Department of Agriculture's soil survey investigations. [ 7 ]
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. [1] It is edited by a working group of the International Union of Soil Sciences (IUSS). WRB, 4th edition (2022)
Rendzina soils are thin soils with limited available water capacity. Terra rossa soils are deep red soils associated with higher rainfall than rendzina. Hydromorphic soils form in wetland conditions. There are two sub-types: Gley soils - These occur when the pore spaces between the grains become saturated with water and contain no air.
The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size of a soil. The classification system can be applied to most unconsolidated materials, and is represented by a two-letter symbol. Each letter is described below (with the exception of Pt): If the ...
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.
Soil texture focuses on the particles that are less than two millimeters in diameter which include sand, silt, and clay. The USDA soil taxonomy and WRB soil classification systems use 12 textural classes whereas the UK-ADAS system uses 11. [1] These classifications are based on the percentages of sand, silt, and clay in the soil.
Soil series as established by the National Cooperative Soil Survey of the United States Department of Agriculture (USDA) Natural Resources Conservation Service are a level of classification in the USDA Soil Taxonomy classification system hierarchy. The actual object of classification is the so-called soil individual, or pedon. [1]