A soil type is a taxonomic unit in soil science. All soils that share a certain set of well-defined properties form a distinctive soil type. Soil type is a technical term of soil classification, the science that deals with the systematic categorization of soils. Every soil of the world belongs to a certain soil type. Soil type is an abstract term. In nature, you will not find soil types. You will find soils that belong to a certain soil type.
Alfisols are a soil order in USDA soil taxonomy. Alfisols form in semi-arid to humid areas, typically under a hardwood forest cover. They have a clay-enriched subsoil and relatively high native fertility. "Alf" refers to aluminium (Al) and iron (Fe). Because of their productivity and abundance, Alfisols represent one of the more important soil orders for food and fiber production. They are widely used both in agriculture and forestry, and are generally easier to keep fertile than other humid-climate soils, though those in Australia and Africa are still very deficient in nitrogen and available phosphorus. Those in monsoonal tropical regions, however, have a tendency to acidify when heavily cultivated, especially when nitrogenous fertilizers are used.
Mollisol is a soil type which has deep, high organic matter, nutrient-enriched surface soil, typically between 60 and 80 cm in depth. This fertile surface horizon, called a mollic epipedon, is the defining diagnostic feature of Mollisols. Mollic epipedons are created by long-term addition of organic materials derived from plant roots and typically have soft, granular soil structure.
A vertisol is a Soil Order in the USDA soil taxonomy and a Reference Soil Group in the World Reference Base for Soil Resources (WRB). It is also defined in many other soil classification systems. In the Australian Soil Classification it is called vertosol. The natural vegetation of vertisols is grassland, savanna, or grassy woodland. The heavy texture and unstable behaviour of the soil makes it difficult for many tree species to grow, and forest is uncommon.
Entisols are soils, as defined under USDA soil taxonomy, that do not show any profile development other than an A-horizon. Entisols have no diagnostic horizons, and are unaltered from their parent material, which could be unconsolidated sediment, or rock. Entisols are the most common soils, occupying about 16% of the global ice-free land area.
An Acrisol is a Reference Soil Group of the World Reference Base for Soil Resources (WRB). It has a clay-rich subsoil and is associated with humid, tropical climates, such as those found in Brazil, and often supports forested areas. In the USDA soil taxonomy, Acrisols correspond to the Humult, Udult and Ustult suborders of the Ultisols and also to Oxisols with a kandic horizon and to some Alfisols. The Acrisols low fertility and toxic amounts of aluminium pose limitations to its agricultural use, favouring in many places its use for silviculture, low intensity pasture and protected areas. Crops that can be successfully cultivated, if climate allows, include tea, rubber tree, oil palm, coffee and sugar cane.
Solonetz is a Reference Soil Group of the World Reference Base for Soil Resources (WRB). They have, within the upper 100 cm of the soil profile, a so-called "natric horizon". A subsurface horizon (subsoil), higher in clay content than the upper horizon, has more than 15% exchangeable sodium. The name is based on the Russian соль. The Ukrainian folk word "solontsi" means salty soil. In Ukraine, many villages are called Solontsі.
Brown earth is a type of soil. Brown earths are mostly located between 35° and 55° north of the Equator. The largest expanses cover western and central Europe, large areas of western and trans-Uralian Russia, the east coast of America and eastern Asia. Here, areas of brown earth soil types are found particularly in Japan, Korea, China, eastern Australia and New Zealand. Brown earths cover 45% of the land in England and Wales. They are common in lowland areas on permeable parent material. The most common vegetation types are deciduous woodland and grassland. Due to the reasonable natural fertility of brown earths, large tracts of deciduous woodland have been cut down and the land is now used for farming. They are normally located in regions with a humid temperate climate. Rainfall totals are moderate, usually below 76 cm per year, and temperatures range from 4 °C in the winter to 18 °C in the summer. They are well-drained fertile soils with a pH of between 5.0 and 6.5.
Inceptisols are a soil order in USDA soil taxonomy. They form quickly through alteration of parent material. They are more developed than Entisols. They have no accumulation of clays, iron oxide, aluminium oxide or organic matter. They have an ochric or umbric horizon and a cambic subsurface horizon.
A petrocalcic horizon is a diagnostic horizon in the USDA soil taxonomy (ST) and in the World Reference Base for Soil Resources (WRB). They are formed when secondary calcium carbonate or other carbonates accumulate in the subsoil to the extent that the soil becomes cemented into a hardpan. Petrocalcic horizons are similar to a duripan and a petrogypsic horizon (WRB) in how they affect land-use limitations. They can occur in conjunction with duripans where the conditions are right and there are enough free carbonates in the soil. Calcium carbonates are found in alkaline soils, which are typical of arid and semiarid climates. A common field test for the presence of carbonates is application of hydrochloric acid to the soil, which indicates by fizzing and bubbling the presence of calcium carbonates.
A Leptosol in the World Reference Base for Soil Resources (WRB) is a very shallow soil over continuous rock or a deeper soil that is extremely rich in coarse fragments. Leptosols cover approximately 1.7 billion hectares of the Earth's surface. They are found from the tropics to the cold polar regions and from sea level to the highest peaks. Leptosols are particularly widespread in mountain areas, notably in Asia, South America, northern Canada and Alaska; and in the Saharan and Arabian deserts. Elsewhere, Leptosols can be found on hard rocks or where erosion has kept pace with soil formation or removed the top of the soil. In the FAO soil classification for the FAO/UNESCO Soil Map of the World (1974) the Leptosols on calcareous rock were called Rendzinas, those on acid rock were Rankers. The very shallow, less than 10 cm deep, Lithic Leptosols in mountain regions are the most extensive Leptosols on Earth.
A Durisol is a Reference Soil Group under the World Reference Base for Soil Resources (WRB) referring to free-draining soils in arid and semi-arid environments that contain grains cemented together by secondary silica (SiO2) in the upper metre of soil, occurring either as concretions (durinodes – duric horizon) or as a continuously cemented layer (duripan – hardpan (Australia) – dorbank (South Africa) – petroduric horizon). The name is derived from Latin durus for hard.
A Planosol in the World Reference Base for Soil Resources is a soil with a light-coloured, coarse-textured, surface horizon that shows signs of periodic water stagnation and abruptly overlies a dense, slowly permeable subsoil with significantly more clay than the surface horizon. In the US Soil Classification of 1938 used the name Planosols, whereas its successor, the USDA soil taxonomy, includes most Planosols in the Great Groups Albaqualfs, Albaquults and Argialbolls.
A Stagnosol in the World Reference Base for Soil Resources (WRB) is soil with strong mottling of the soil profile due to redox processes caused by stagnating surface water.
An Alisol is a Reference Soil Group of the World Reference Base for Soil Resources (WRB).
A fluvisol in the World Reference Base for Soil Resources (WRB) is a genetically young soil in alluvial deposits. Apart from river sediments, they also occur in lacustrine and marine deposits. Fluvisols correlate with fluvents and fluvaquents of the USDA soil taxonomy. The good natural fertility of most fluvisols and their attractive dwelling sites on river levees and higher parts in marine landscapes were recognized in prehistoric times.
Luvisols are a group of soils, comprising one of the 32 Reference Soil Groups in the international system of soil classification, the World Reference Base for Soil Resources (WRB). They are widespread, especially in temperate climates, and are generally fertile. Luvisols are widely used for agriculture.
Nitisol, in the World Reference Base for Soil Resources (WRB), is a deep, red, well-drained soil with a clay content of at least 30% and a polyhedral structure or a blocky structure, breaking into a polyhedral or a flat-edged structure. The soil aggregates show pressure faces. Nitisols correlate with the kandic alfisols, ultisols and inceptisols of the USDA soil taxonomy.
The Polish Soil Classification is a soil classification system used to describe, classify and organize the knowledge about soils in Poland.
A Retisol is a Reference Soil Group of the World Reference Base for Soil Resources (WRB). Retisols are characterized by clay migration and an additional specific feature: The clay-poorer and lighter coloured eluvial horizon intercalates netlike into the clay-richer more intensely coloured illuvial horizon. The illuvial horizon is the diagnostic argic horizon, and the intercalation is called retic properties.
