Umbrisol

The Umbrisol (UM) (from the Latin umbra = shade and solum = soil) is a reference soil group of the World Reference Base for Soil Resources (WRB). Umbrisols can be called acidic humus accumulation soils .

description

The uppermost mineral soil horizon is dark, thick and rich in humus and is called umbric horizon in the WRB . The umbric horizon may still organic Edition horizons be covered, but are only slightly powerful in general. The umbric horizon is similar to the mollic horizon . B. occurs in the phaeozemes . In contrast to that, however, the umbric horizon is relatively acidic and has a low base saturation .

Umbrisols occur on acid parent rocks and / or in areas with high levels of precipitation. Base cations were therefore never available in large quantities or were washed out. On the other hand, the conditions for the soil animals are so good that no powerful organic layers with subsequent podzolation can develop. The weathering of the subsoil is not yet very advanced, at least no ferrallitization has taken place.

Umbrisoles are found in the oceanic areas of the humid middle latitudes , z. B. in north-west Spain , Ireland or Norway as well as in the north-west of the USA (for example in Oregon ). They are also widespread in mountains. On the one hand, this applies to the temperate zone, i.e. in Central Europe e.g. B. for the Black Forest , the Bavarian Forest or the Silica Alps . On the other hand, they can also be found in tropical mountains, for example in the Andes or the mountainous countries of East Africa or New Guinea .

With suitable fertilization and liming, high arable yields can be achieved on Umbrisoles. However, forestry or grazing are more common. Intensive liming can transform umbrisols into phaeozemes .

Related soil types

Umbrisols are lower in base than the phaeozemes related to them . This is expressed by the fact that they typically have the poorly base umbric horizon instead of the base-rich mollic horizon . However, some soils with a mollic horizon also belong to the umbrella group, namely those that have a low base saturation below their mollic horizon and thus fail to meet the criteria for phaeozemes, chernozemes and kastanozemes .

According to the German soil systematics , the umbrisols belong primarily to the humus brown soils , humus parabroun soils , regosols and tendrils . Some floodplain soils are also umbrisoles.

Web links

• Profile photos (with classification) WRB homepage
• Profile photos (with classification) IUSS World of Soils

literature

• IUSS Working Group WRB: World Reference Base for Soil Resources 2014, Update 2015. World Soil Resources Reports 106, FAO, Rome 2015. ISBN 978-92-5-108369-7 ( PDF 2.3 MB).
• W. Zech, P. Schad, G. Hintermaier-Erhard: Soils of the world. 2nd Edition. Springer Spectrum, Heidelberg 2014. ISBN 978-3-642-36574-4 .
• 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 .