AStagnosol in theWorld Reference Base for Soil Resources (WRB) issoil with strong mottling of thesoil profile due toredox processes caused by stagnating surfacewater.
Stagnosols are periodically wet andmottled in the topsoil andsubsoil, with or withoutconcretions and/or bleaching. The topsoil can also be completely bleached (albichorizon). A common name in many national classification systems for most Stagnosols ispseudogley. In theUSDA soil taxonomy, many of them belong to the Aqualfs, Aquults, Aquents, Aquepts and Aquolls.
They are developed in a wide variety of unconsolidated materials likeglacial till, andloamyaeolian,alluvial andcolluvialdeposits andphysically weathered siltstone. Stagnosols occur on flat to gently sloping land in cooltemperate tosubtropical regions withhumid to perhumid climate conditions.
Theagricultural suitability of Stagnosols is limited because of theiroxygen deficiency resulting from stagnating water above a dense subsoil. Therefore, they have to be drained. However, in contrast toGleysols, drainage with channels or pipes is in many cases insufficient. It is necessary to have a higherporosity in the subsoil in order to improve thehydraulic conductivity. This may be achieved by deep loosening or deep ploughing. Drained Stagnosols can befertile soils owing to their moderate degree of leaching.
Stagnosols cover 150–200 million ha worldwide. For the greater part in humid to perhumid temperate regions ofWest andCentral Europe,North America, southeastAustralia andArgentina. Here Stagnosols are associated withLuvisols as well assilty toclayeyCambisols andUmbrisols. They also occur in humid to perhumid subtropical regions, where they are associated withAcrisols andPlanosols.with a light-coloured,coarse-textured, surfacehorizon that shows signs of periodicwater stagnation and abruptly overlies a dense, slowlypermeable subsoil with significantly more clay than the surface horizon. In the US Soil Classification of 1938 used the name Planosols, whereas its successor, theUSDA soil taxonomy, includes most Planosols in theGreat Groups Albaqualfs, Albaquults and Argialbolls.
