Intensely weathered, low base status soils with oxidic mineralogy and exceptional accumulation of humus develop in areas of high rainfall, free drainage and plateau topography.
They have stable, micro-aggregate structure and low erodibility. Biomass potential is large but limited by nutrient deficiency and acidity. Chemical amendment is needed to make them highly productive. Natural veld on these soils is sour.
Some variants have an exceptionally thick humic A horizon, thought to be related to the depth of pedoturbation by soil fauna. Aluminium forms a complex with the humus, making it less retentive towards nutrient cations but more resilient (Soil forms: Kranskop, Magwa, Inanda, Lusiki, Sweetwater, Nomanci).
Source : http://sis.agr.gc.ca