Kolluvisol

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Kolluvisols are soils made of humus soil material that has been displaced by runoff . In soil science, however, they are primarily addressed as anthropogenic soils in which the relocation of humus soil material occurs through tillage during agriculture .

Emergence

Basically, colluvium is formed in colluvium that was created by the washing away of terrain higher up. The accumulation of the soil material removed by water and partly by wind occurs at the foot of slopes , in depressions and small valleys or on embankments and slope edges. This causes a steady loss of humus topsoil, which is deposited in lower terrain and forms the starting material for the development of the Kolluvisol soil type.

Kolluvisole are also a typical feature of landscapes used intensively for agriculture, e.g. B. the Uckermark , and can arise here very quickly through anthropogenic relocation ( plowing ). In this form they have a large share in the cultural landscape not only in Europe.

Soil profile

The Kolluvisol soils consist largely of loamy runoff masses and relocated bottom sediments and can reach a thickness of several meters. Their properties are similar to those of their raw materials.

The typical soil profile of a naturally formed Kolluvisol consists of the soil horizons A - M - C. Under a humus topsoil (A) there is an M horizon (soil horizon made of rearranged, mostly humus soil material), which together with the A- Horizon must be at least 40 cm thick. Depending on the starting material, this can be structured differently. Older soil profiles may be preserved below the relocation horizon or the transition to the unweathered rock (C) may take place. The C horizon can differ greatly from the overlying soil profile due to the transport processes; in this case it is not the starting rock of the overlying soil.

In agriculturally used areas, the topsoil is usually a field horizon (Ap, homogenized by cultivation, or E, enriched with compost or pests ), which consists of a mixture of the humus topsoil with the material underneath that was created during plowing. In Germany, the Kolluvisol is classified like the Plaggenesch , the Hortisol or the Rigosol in the group of terrestrial Kultosols .

In the international soil classification World Reference Base for Soil Resources (WRB), Kolluvisol is expressed by the qualifier Colluvic. The Kolluvisols then belong to different reference soil groups depending on their further properties. Common are Regosol , Cambisol , Phaeozem and Umbrisol .

In northern Germany in particular, a waterlogging horizon (S) is often formed in deeper areas. Such processes of waterlogging by groundwater or backwater (gleying and pseudogley ) or boggy contribute to the differentiation and diversity of the Kolluvisole.

properties

With a sufficient humus content, Kolluvisols have good water retention capacity, can store nutrients well and serve as a buffer for material transport, as they have the properties of a temporary storage. In agricultural regions, they also provide information about the cultural and landscape history.

Kolluvisols are at risk from waterlogging and crust formation, which can lead to impairment and loss of their positive properties. In addition, they are endangered in agricultural regions by the entry of fertilizers and pesticides.

literature

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