World’s Soil Resources

Figure 9.11 The national stratification used for land degradation assessment in South Africa, incorporating local municipality
boundaries with 18 land use classes. Source: Pretorius, 2009.
Erosion assessment
A separate spatial study was conducted on the extent of gully erosion in South Africa (Le Roux et al., 2008).
The study also assessed national erosion potential in terms of soils, climate and topography (Le Roux, 2012).
The assessment of water erosion susceptibility indicated that around 20 percent (26 million ha) of the country
is classified as having a moderate to severe erosion risk (mainly based on sheet-rill erosion). The affected
areas are concentrated in the south-eastern and north-eastern interior, mainly in the Eastern Cape, KwaZulu-
Natal, Mpumalanga and Limpopo Provinces. All of these areas are characterized by a combination of high
(often intense) rainfall, duplex soils derived from sodium-rich parent materials, and steep slopes (see Figure
9.12). These natural conditions are often exacerbated by poor land use practices, such as incorrect cultivation
methods, overgrazing by livestock and high population density. Under such circumstances, potential soil loss
can easily be in the ‘Very High’ class of more than 50 tonnes ha -1 yr -1 (Le Roux et al., 2006).
Status of the World’s Soil Resources | Main Report Regional Assessment of Soil Changes
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in Africa South of the Sahara