Soils

The  soils  of  the  Mefou  Catchment  are  the  typical  soils  of  the  southern  parts  of  Cameroon. According to the World Reference Database, the soils might be classified as Ferralosols.

In the local classification system, there a three subtypes of ferralitic soils:

  • Red  and  yellow  ferralitic  soils  cover  most  of  the  catchment,  especially  the  mid‐altitudes and the summits. They are deeply weathered (sometimes more than 15 m), have a high clay content and are acidic (pH > 5.5). The main clay minerals are kaolinite, haematite, goethite, quartz and gibbsite. At the foot of the hills the soils are more yellow, also rich in clay minerals (especially quartz) and iron, but less stable than the red soils.
    Deep  red  soils  are  also  known  as  lateritic  soils,  because  of  the  presence  of  an accumulation horizon, containing oxides and hydroxides of iron and aluminium. Agriculture on red or yellow soils is possible after clearing the forest, but due to the low fertility of the soils – most of the nutrients are stored in the biomass – the cultivation system has to take into account the poor soil quality. Besides farming, red soils are used to produce bricks to build traditional houses. They are also a relatively good material for creating unpaved roads.
  • Shallower soils are located in areas characterised by high relief and steep slopes. The soils  have low humus content and unweathered rocks are close to the surface. These soils are strongly  influenced  by  tree  coverage,  in  that  the  roots  of  the  trees  tend  to  hold  the substratum in place. Due to their topographic position and the shallow depth of these soils they are normally not used for agriculture.
  • Hydromorphic ferralitic soils are located In the river valleys. They are of a blackish colour, have higher humus content than the soils higher in the catchment, are therefore more fertile. Yields of plants grown on these hydromorphic soils are much higher than those grown on red or yellow soils.  The  concentration  of  sesquioxides  (of  aluminium  and  iron)  gives  the  soils  a  good aggregate stability, which means their susceptibility to being destroyed by raindrops, or to being transported by overland flow, is low. In addition, the high clay content lessens the risk of soil erosion.