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 (
Latin: rete = net).
Retisols were newly introduced with the third edition of the WRB in 2014. They include the narrower defined Albeluvisols[W. Zech, P. Schad, G. Hintermaier-Erhard: Böden der Welt. 2. Auflage. Springer-Spektrum, Heidelberg 2014, .] of the first and second edition (1998 and 2006), which were abolished in 2014. The definition of the Retisols resembles the definition of the Podzoluvisols of the Legend (1974) and the Revised Legend (1988) of the FAO soil classification.
Horizonation
A typical
soil horizon according to Annex 3 of the WRB is:
-
A – mineral topsoil, usually with relatively low organic matter concentrations
-
E – horizon that lost clay (eluvial horizon)
-
Bt/E – intercalating eluvial/illuvial horizon ( argic horizon with retic properties)
-
Bt – horizon that gained clay (illuvial horizon, argic horizon)
-
C – more or less unweathered material (parent material)
Occurrence and use
Retisols occur mainly in periglacial areas of the last
glaciation in Europe and North America. In Europe, they are found along a belt from Belgium through northern Germany, Poland and Belarus to Russia. Because the very specific retic properties are not so widespread, they normally do not cover larger areas.
Most Retisols are dominated by high-activity clays and show a low base saturation. Many are used as forest[W.E.H. Blum, P. Schad, S. Nortcliff: Essentials of Soil Science. Soil formation, functions, use and classification (World Reference Base, WRB). Borntraeger Science Publishers, Stuttgart 2018. ] or pasture land. Especially their physical conditions are not good for agriculture. The are often poor in and iron oxides. In the subsoil, the rainwater runs downwards predominantly in the clay-poorer parts, whereas the clay-richer and therefore also nutrient-richer parts are often insufficiently humid. The clay-richer parts are relatively dense and difficult to be rooted. These characteristics make the Retisols also unattractive for many soil animals, especially earthworms. Retisols have typically or that are prone to erosion.
Relationships with other Reference Soil Groups
The WRB defines five Reference soil Groups with a compulsory
argic horizon. Only the Retisols have
retic properties. The other four are differentiated according to the cation exchange capacity per kg
clay at pH 7 (CEC / kg clay) in the
argic horizon and according to the
base saturation calculated per sum of exchangeable cations (BSeff) in the subsoil. For
both values are high.
have a high CEC and a low BS.
have a low CEC and a high BS. For
both values are low. Soils with an
argic horizon and
retic properties that are dominated by
water stagnation are classified as Retic
.
Further reading
-
W. Zech, P. Schad, G. Hintermaier-Erhard: Soils of the World. Springer, Berlin 2022, Chapter 3.3.4.
External links
