A Naturally degraded humus form (German: Hagerhumus) is observed after the export of litter due to translocation by wind, for example. Reduced input of nutrients causes a deterioration of the topsoil. This normally leads to a change of the soil structure in the very upper soil layer (1 cm), to a single grain structure in sandy soils, or in more clayey soils to a coherent structure. In the vicinity of humus forms with an organic surface layer, at positions with deteriorated humus forms, an Oh horizon is partly absent or incomplete. Naturally deteriorated humus forms are clearly differentiated from Mull humus forms with an Ax horizon by an A horizon with less soil aggregation. The humus form is characterised by:
extensive uncovered surface of the mineral soil despite existing vegetation or
sporadically occurring soil crust on the surface of the mineral soil consisting of algae, lichens, or a thin cover with mosses.