A sapric is a subtype of a histosol where virtually all of the organic material has undergone sufficient decomposition to prevent the identification of plant parts. Muck is a sapric soil that is naturally waterlogged or is artificially drained.
Oxisols are a soil order in USDA soil taxonomy, best known for their occurrence in tropical rain forest within 25 degrees north and south of the Equator. In the World Reference Base for Soil Resources (WRB), they belong mainly to the ferralsols, but some are plinthosols or nitisols. Some oxisols have been previously classified as laterite soils.
USDA soil taxonomy (ST) developed by the United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate classification of soil types according to several parameters and in several levels: Order, Suborder, Great Group, Subgroup, Family, and Series. The classification was originally developed by Guy Donald Smith, former director of the U.S. Department of Agriculture's soil survey investigations.
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.
In soil science, podzols are the typical soils of coniferous or boreal forests and also the typical soils of eucalypt forests and heathlands in southern Australia. In Western Europe, podzols develop on heathland, which is often a construct of human interference through grazing and burning. In some British moorlands with podzolic soils, cambisols are preserved under Bronze Age barrows.
A soil horizon is a layer parallel to the soil surface whose physical, chemical and biological characteristics differ from the layers above and beneath. Horizons are defined in many cases by obvious physical features, mainly colour and texture. These may be described both in absolute terms and in terms relative to the surrounding material, i.e. 'coarser' or 'sandier' than the horizons above and below.
In both the World Reference Base for Soil Resources (WRB) and the USDA soil taxonomy, a Histosol is a soil consisting primarily of organic materials. They are defined as having 40 centimetres (16 in) or more of organic soil material in the upper 80 centimetres (31 in). Organic soil material has an organic carbon content of 12 to 18 percent, or more, depending on the clay content of the soil. These materials include muck, mucky peat, or peat. Aquic conditions or artificial drainage are required. Typically, Histosols have very low bulk density and are poorly drained because the organic matter holds water very well. Most are acidic and many are very deficient in major plant nutrients which are washed away in the consistently moist soil.
In gelisols, cryoturbation refers to the mixing of materials from various horizons of the soil down to the bedrock due to freezing and thawing.
In USDA soil taxonomy, Entisols are defined as soils that do not show any profile development other than an A horizon. An entisol has no diagnostic horizons, and most are basically unaltered from their parent material, which can be unconsolidated sediment or rock. Entisols are the most abundant soil order, occupying about 16% of the global ice-free land area.
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. It is edited by a working group of the International Union of Soil Sciences (IUSS).
In environments containing permafrost, the active layer is the top layer of soil that thaws during the summer and freezes again during the autumn. In all climates, whether they contain permafrost or not, the temperature in the lower levels of the soil will remain more stable than that at the surface, where the influence of the ambient temperature is greatest. This means that, over many years, the influence of cooling in winter and heating in summer will decrease as depth increases.
Gypsisols in the World Reference Base for Soil Resources (WRB) are soils with substantial secondary accumulation of gypsum (CaSO4.2H2O). They are found in the driest parts of the arid climate zone. In the USDA soil taxonomy they are classified as Gypsids (USDA Soil Taxonomy), in the Russian soil classification they are called Desert soils (USSR).
The Canadian System of Soil Classification is more closely related to the American system than any other, but they differ in several ways. The Canadian system is designed to cover only Canadian soils. The Canadian system dispenses with the sub-order hierarchical level. Solonetzic and Gleysolic soils are differentiated at the order level.
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 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.
A frost boil, also known as mud boils, a stony earth circles, frost scars, or mud circles, are small circular mounds of fresh soil material formed by frost action and cryoturbation. They are found typically found in periglacial or alpine environments where permafrost is present, and may damage roads and other man-made structures. They are typically 1 to 3 metres in diameter.
Kastanozem is one of the 32 Reference Soil Groups of the World Reference Base for Soil Resources (WRB). These soils are brighter than Chernozems, and are related to the Mollisols in the USDA soil taxonomy. They are rich in humus, and originally covered with early maturing native grasslands vegetation, which produces a characteristic brown surface layer in the first meter in depth. They have a relative high level of available calcium ions bound to soil particles and can have a petrocalcic horizon between 25 and 100 cm thick.
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.
The Polish Soil Classification is a soil classification system used to describe, classify and organize the knowledge about soils in Poland.
