The Role of Sustainable Land Management for Climate ... - CAADP

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widespread in all regions and remains a major constraint to agricultural productivity (Verchot et
al. 2007) and aluminum toxicity and low cation exchange capacity are major constraints on the
continent (FAO 2000). Henao and Banaante (2006) estimate that 85 percent of African
farmland had nutrient mining rates of more than 30 kg/ha of nutrients annually and 40% of land
had mining rates of over 60 kg/ha per year. If these figures are extrapolated to the roughly 190
million hectares of cultivated land in Africa, this would translate into a fertilizer replacement
cost of well over $500 million in 2006 and even more in 2008, with soaring fertilizer prices.
Increases in agricultural production have largely been met through opening up new land to
cultivation and have been obtained at the cost of soil degradation as soils are mined for their
nutrients.
The consequences are enormous. Agricultural productivity has been stagnant on the
continent, whereas it has increased markedly elsewhere. As much as 25% of land productivity
has been lost to degradation in the second half of the 20th century in Africa (Oldeman 1998).
Because of the importance of agriculture to African economies, this has cost between 1% to 9%
of GDP, depending on the country (Dregne and Kassas 1991; Dreschel et al 2001). Few African
countries are self-sufficient in food production, resulting in massive annual food imports. At the
household level, rural poverty rates in Africa remain high, with an increase of the number of
rural poor between 1993 and 2002 (World Bank 2007). In 2001, about 28 million Africans faced
food emergencies due to catastrophic events (e.g. flooding) that were caused or exacerbated by
land degradation (FAO 2001b).
3.1.1. Causes of land degradation
The important proximate causes of land degradation are:
• Conversion of forests, woodlands, and bushlands which are ill-suited to permanent
agriculture;
• Overgrazing of rangelands;
• Excessive exploitation of natural habitats (e.g. harvesting for fuelwood in woodlands);
and
• Unsustainable agricultural practices (e.g., farming on steep slopes without sufficient use
of soil and water conservation measures, excessive tillage, declining use of fallow
without application of soil nutrients).
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