Soil type

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As soil type in the are Bodenkunde different manifestations of floors designated, as a result of the processes of Pedogenese matching features in the form of soil horizons have produced, thus having a similar stage of development. These are classified worldwide in the soil classification or the soil systematics according to different systems.

While the soil type describes the appearance of a soil as a result of soil formation , soil types (also called soil texture or grain size ) are differentiated according to the grain size composition of the mineral soil substance. The main types of soil are sand , silt , clay, and loam . Since the soil type often changes within a soil profile , it is usually specified separately for each horizon.

Basics

When digging up soils , differentiated "layers" can be seen in terms of substrate and / or color, which are known as soil horizons . (The term layers in soil science only refers to forms of sedimentation, a process of lithogenesis .)

The differentiation results on the one hand from the starting materials for soil formation ( pedogenesis ), on the other hand from soil chemical processes. These result, among other things, from different climatic influences, the water balance, the vegetation , the soil fauna , possibly the processing, the immissions and the natural environment (e.g. water accumulates in sinks or floodplains). Between these factors there are many influences , some of which are fed back .

Soil horizons appear in various characteristic combinations. These are systematically divided into soil types. Here, horizon sequences in the soil profile are described in which similar chemical and physical changes have produced matching features and thus similar horizons and horizon combinations. The soil type characterizes the state of development of a soil.

The differences in the horizons can be of different origins. Often organic or mineral substances are dissolved, relocated and deposited in storage horizons.

It is important that soil types rarely appear in their "pure form", but that combinations and transitions of soil types can often be found through pedogenetic processes that take place simultaneously or one after the other. Depending on their characteristics, these lead to the classification of soil subtypes (transition and deviation subtypes) and varieties. In this way, a number of different characteristics can be determined for each soil type, and the relationship between the individual soil types can be described. In the landscape, the different soil types (or sub-types) appear as a small-area mosaic ( soil society ), as the individual locations differ in the influence of soil-forming factors and a lateral exchange of substances often takes place.

The German Soil Systematics - Central European Soil Types

Almost every European country and numerous other countries around the world have their own classification systems. In the following, the Central European soil types are to be classified hierarchically (department, class, type, subtype, variety) according to soil systematic units. The system on which this page is based (the German Soil Systematics ) is valid in Germany and is worked on and regularly developed by the Soil Systematics working group of the German Soil Science Society . The currently valid status is shown in the 5th edition (2005) of the Soil Science Mapping Guide .

Terrestrial Soils Department

Terrestrial soils are soils that were created outside the groundwater area and in which the movement of water is primarily directed from top to bottom. The Terrestrial Soils Department is divided into 13 classes.

Class F - O / C floors

Class O - Terrestrial raw floors

Class R - Ah / C soils except black earths

Class T - black earths

Class D - Pelosols

Class B - brown earth

Class L - Lessivés

Class P - Podsole

Class C - Terrae calcis

Class V - Fersiallitic and Ferrallitic paleo soils

Class S - backwater bottoms (waterlogged bottoms)

Class X - reductosols

  • XX - Reduktosol (created by natural or anthropogenic reducing conditions that are not due to water saturation)

Class Y - Terrestrial anthropogenic soils

Department of Semiterrestrial Soils (Groundwater Soils)

Semiterrestrial soils are under the influence of groundwater and can at times also be subject to flooding. However, the flooding periods are irregular and short-term. There are four classes in the department with a total of 17 soil types.

Class A - floodplain soils

Class G - Gleye

Class M - marshes

Class Ü - beach floors

Department of Semi-Subhydric and Subhydric Soils

Semisubhydric soils are subject to regular flooding, but are also sometimes dry ( tidal range ). Subhydric soils are permanently under water. It should be noted that only inland waters are considered. The classification of submarine soils is currently at a very low level of knowledge and, with reservations, is not considered in any of the worldwide classifications.

Class I - semi-subhydric soils

Class J - Subhydric Soils (Underwater Soils)

Moore Department

Class H - natural moors

Class K - earth and Mulmmoore

Classification of the anthropogenic soil types

Anthropogenic soils exist when their formation can only be caused by human activities. In the German Soil Systematics, their classification is sometimes only weak.

In the international soil classification WRB , a distinction is made between anthrosols (cultivars) and technosols : The anthrosols arise through certain forms of cultivation. This group is taken up in the KA5 with five soil types (class Y), whereby only the Hortisole and Plaggenesche in the sense of the WRB belong to the Anthrosols.

The technosols, which consist of artificially produced or relocated materials, are sometimes also referred to as city ​​floors . Other classic technosols (e.g. soils from rubbish dumps) partly fall into the soil type Reductosol (in a separate class (class X). Other types are not listed as separate soil types in Germany either. Instead, according to the predominant process of pedogenesis, the selected natural soil type that comes closest to the urban soil. In maps, humanly shaped areas are often represented without further differentiation under a collective term such as “dump, settlement, traffic, etc.” Critics of the KA5 therefore believe that the soil-scientific mapping instructions only apply to natural soils They overlook the fact that with the soil shape, ie the combination of a (pedo-) genetic soil systematic unit (usually the soil type or subtype) with the substrate systematic unit, an appropriate identification of a soil can usually be achieved Soil shape in urban soil science has not yet been implemented since KA4 , is often referred to the WRB or other own classifications are used.

Important non-European soil types

Internationally, two classification systems for soils in particular are very common, the USDA Soil Taxonomy and the World Reference Base for Soil Resources (WRB).

The Soil Taxonomy divides all soils worldwide into twelve orders, which are then subdivided into sub-orders, etc. The WRB subdivides the soils of the world into 32 reference soil groups, which are specified by adding qualifiers.

See also

literature

  • Ad-hoc Working Group Soil: Soil Science Mapping Instructions , Ed .: Federal Institute for Geosciences and Raw Materials in cooperation with the State Geological Services, 5th edition, 438 p .; 41 figs., 103 tabs., 31 lists, Hannover 2005, ISBN 3-510-95920-5 .
  • AG BODEN: Bodenkundliche Kartieranleitung , Ed .: Federal Institute for Geosciences and Natural Resources and Geological State Offices, 4th edition, 392 pages, 33 figs., 91 tabs., Hannover 1994, ISBN 3-510-95804-7 .
  • AG Bodenkunde: Bodenkundliche Kartieranleitung , Ed .: Federal Institute for Geosciences and Natural Resources and Geological State Offices, 3rd edition, 331 pages, 19 figs., 98 tabs., 1 supplement., Hannover 1982.
  • AG Soil Science: Bodenkundliche Kartieranleitung , Ed .: Working Group Soil Science of the Geological State Offices and the Federal Institute for Raw Materials, 2nd edition, 169 pp., 4 figs., 30 tabs., 1 tab., Hanover 1971.
  • W. Amelung, H.-P. Blume , H. Fleige, R. Horn, E. Kandeler , I. Kögel-Knabner , R. Kretschmar, K. Stahr , B.-M. Wilke: Scheffer / Schachtschabel textbook of soil science. 17th edition. Heidelberg 2018. ISBN 978-3-662-55870-6 .

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