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Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use.
Overview Soil classification is a dynamic subject, from the structure of the system itself, to the definitions of classes, and finally in the application in the field. It can be approached from both the pespective of pedogenesis and from soil morphology. Differing concepts of pedogenesis, and differences in the significance of morphological features to various land uses can affect the classification approach. Despite these differences, in a well-constructed system, classification criteria group similar concepts so that interpretations do not vary widely. Appliction in the field is a challenge due to the complex nature of soil formation and the inherent opacity of the soil resource.
Types by discipline
Marlin Cline ("Basic principles of soil classification", Soil Science, 2:81–91, 1949) stated the basic rationale behind utilitarian classification: Soil science deals with soil as a natural resource on the surface of the earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils per se; and these properties in relation to the use and management of soils. ...
- "The purpose of any classification is so to organize our knowledge that the properties of objects may be remembered and their relationships may be understood most easily for a specific objective. The process involves formation of classes by grouping the objects on the basis of their common properties. In any system of classification, groups about which the greatest number, most precise, and most important statements can be made for the objective serve the purpose best."
For soils, experience has shown that a natural system, i.e. grouping soils by their intrinsic property, behaviour, or genesis, results in classes that can be interpreted for many diverse uses. This is in contrast to a technical classification (such as the Fertility Capability Classification), where soils are grouped according to their fitness for a specific use. Natural systems are based strictly on presumed soil genesis, but modern hierarchical systems such as USDA soil taxonomy and the World Reference Base for Soil Resources use objective criteria (both field morphology and laboratory tests) as far as possible, to reduce disagreements among classifiers. Pedogenesis or soil evolution (formation) is the process by which soil is created. ...
USDA Soil Taxonomy developed by United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate classification of soil types according to several parameters (most commonly their properties) and in several levels: Order, Suborder, Great Group, Subgroup, Family, and Series. ...
The World Reference Base for Soil Resources (WRB) is the international standard soil classification system endorsed by the International Union of Soil Sciences (IUSS). ...
Another approach is numerical classification, also called ordination, where soil individuals are grouped by multivariate statistical methods such as cluster analysis. This is supposed to create natural groupings without requiring any inference about soil genesis. Data clustering is a common technique for data analysis, which is used in many fields, including machine learning, data mining, pattern recognition, image analysis and bioinformatics. ...
In soil survey, as practiced in the United States, soil classification usually means criteria based on soil morphology in addition to characteristics developed during soil formation. Criteria are designed to guide choices in land use and soil management. As indicated, this is a hierarchical system that is a hybrid of both natural and objective criteria. 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. Soil taxonomy based soil map units are additionally sorted into classes based on technical classification systems. Land Capability Classes, hydric soil, and prime farmland are some examples. Soil survey is the process of determining the soil types or other properties of the soil cover over a landscape, and mapping them for others to understand and use. ...
// Soil Macromorphology Soil morphology is the field observable attributes of the soil within the various soil horizons and the description of the kind and arrangement of the horizons (Buol et al 2003). ...
Pedogenesis or soil evolution (formation) is the process by which soil is created. ...
USDA Soil Taxonomy developed by United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate classification of soil types according to several parameters (most commonly their properties) and in several levels: Order, Suborder, Great Group, Subgroup, Family, and Series. ...
The 1938 USDA soil taxonomy was a soil classification system adopted by the United States Department of Agriculture, now obsolete. ...
Dude, they should have something on hydric soil if they mention it. ...
Prime farmland in 1997 Prime farmland, as a designation assigned by U.S. Department of Agriculture is land that has the best combination of physical and chemical characteristics for producing food, feed, forage, fiber, and oilseed crops and is also available for these uses. ...
In addition to scientific soil classification systems, there are also vernacular soil classification systems. Vernacular (descriptive) systems have been used for millennia, while scientifically based systems are relatively recent developments. [1]
Engineering Geotechnical engineers classify soils, or more properly earth materials, for their properties relative to foundation support or use as building material. These systems are designed to predict some of the engineering properties and behavior of a soil based on a few simple laboratory or field tests, though some earlier systems were adaptations of soil-science classification systems. The most common is the Unified Soil Classification System, with three major groups: (1) coarse-grained, sands and gravels, (2) fine-grained, silts and clays, and (3) highly organic soils (referred to as peat even when the soil is not truly a peat). The first two groups are then subdivided as follows: Bostons Big Dig presented geotechnical challenges in an urban environment. ...
The Unified Soil Classification System (or USCS) is used in engineering, geology and soil science disciplines to describe the texture, grain size, and the shear strength of a soil. ...
Peat in Lewis, Scotland Peat is an accumulation of partially decayed vegetation matter. ...
- Coarse grain: gravels, sands, based on the grain-size of the coarse-grained fraction.
- Fine grain: silts, clays, organics silts & clays, based on plasticity and organic content.
Fine-grained soils are then subdivided according to their plasticity, while coarse-grained soils are subdivided by the presence and properties of the fines or the grain-size distribution of the soil.
A full geotechnical engineering soil description will include other properties of the soil, including color, in-situ moisture content, in-situ strength, and somewhat more detail about the material properties of the soil than is provided by the USCS code.
See also The World Reference Base for Soil Resources (WRB) is the international standard soil classification system endorsed by the International Union of Soil Sciences (IUSS). ...
The FAO 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. ...
This article is in need of attention. ...
Categories: Pages needing attention | Soil science | Stub ...
Soil texture represents the relative composition of sand, silt and clay in soil. ...
The AASHTO Soil Classification System was developed by the American Association of State Highway and Transportation Officials, and is used as a guide for the classification of soils and soil-aggregate mixtures for highway construction purposes. ...
Notes and references - ^ Soil classification systems. Url last accessed 2006-04-18
2006 (MMVI) is a common year starting on Sunday of the Gregorian calendar. ...
April 18 is the 108th day of the year in the Gregorian calendar (109th in leap years). ...
Overviews - Eswaran, H., Rice, T., Ahrens, R., & Stewart, B. A. (Eds.). (2002). Soil classification : a global desk reference. Boca Raton, Fla.: CRC Press.
Current international system - Buol, S.W., F.D. Hole, R.J. McCracken, and R.J. Southard. 1997. Soil Genesis and Classification, 4th Edition. Iowa State Univ. Press, Ames, IA.
- Driessen, P., Deckers, J., Spaargaren, O., & Nachtergaele, F. (Eds.). (2001). Lecture notes on the major soils of the world. Rome: FAO.
- FAO. (1998). World Reference Base for Soil Resources. Rome: Food and Agriculture Organization of the United Nations.
Current natural systems - Agriculture Canada Expert Committee on Soil Survey. (1987). The Canadian system of soil classification (2nd ed.). Ottawa: Canadian Government Publishing Centre.
- Avery, B. W. (1980). Soil classification for England and Wales: higher categories. Cranfield, England: Cranfield University, Soil Survey & Land Research Centre.
- Baize, D., & Girard, M. C. (Eds.). (1995). Référentiel pédologique 1995. Paris: Institut National de la Recherche Agronomique.
- Baize, D., & Girard, M. C. (Eds.). (1998). A sound reference base for soils: The "Référentiel Pédologique" (English translation by Hodgson J.M., Eskenazi N.R., & Baize D. ed.). Paris: Institut National de la Recherche Agronomique.
- Hewitt, A. E. (1992). Soil classification in New Zealand: legacy and lessons. Australian Journal of Soil Research, 30, 843-854.
- Isbell, R. F. (1996). The Australian soil classification. Collingwood, Victoria, Australia: CSIRO.
- Soil Classification Working Group. (1991). Soil classification: a taxonomic system for South Africa. Pretoria: Department of Agricultural Development, RSA.
- Soil Survey Staff. (1999). Soil taxonomy: a basic system of soil classification for making and interpreting soil surveys (2nd ed.). Washington, DC: US Department of Agriculture Soil Conservation Service.
Current technical systems - Boorman, D. B., Hollis, J. M., & Lilly, A. (1995). Hydrology of soil types: a hydrologically-based classification of the soils of the United Kingdom (No. 126): UK Institute of Hydrology.
- Klingebiel, A. A., & Montgomery, P. H. (1961). Land capability classification. Washington, DC: US Government Printing Office.
- Sanchez, P. A., Palm, C. A., & Buol, S. W. (2003). Fertility capability soil classification: a tool to help assess soil quality in the tropics. Geoderma, 114(3-4), 157-185.
- American Society for Testing and Materials, 1985, D 2487-83, Classification of Soils for Engineering Purposes: Annual Book of ASTM Standards. Vol. 04.08, pp 395-408.
Earlier systems, of historical interest - Baldwin, M., Kellogg, C. E., & Thorp, J. (1938). Soil classification. In Soils and men: Yearbook of agriculture (pp. 979-1001). Washington, DC: U.S. Department of Agriculture.
- Simonson, R. W. (1989). Historical aspects of soil survey and soil classification with emphasis on the United States, 1899-1970. Wageningen, NL: International Soil Reference and Information Centre (ISRIC).
The International Soil Reference and Information Centre is an independent foundation funded by the Netherlands Government. ...
Principles - Butler, B. E. (1980). Soil classification for soil survey. Oxford: Oxford Science Publications.Science, 96,
- Cline, M. G. (1949). Basic principles of soil classification. Soil Science, 67(2), 81-91.
- Cline, M. G. (1963). Logic of the new system of soil classification. Soil 17-22.
- Webster, R. (1968). Fundamental objections to the 7th approximation. Journal of Soil Science, 19, 354-366.
Numerical classification - McBratney, A. B., & de Gruijter, J. J. (1992). A continuum approach to soil classification by modified fuzzy k-means with extragrades. Journal of Soil Science, 43(1), 159-175.
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