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A visible impact of land degradation is soil loss. Information regarding rates of soil loss in Africa are fragmented and country-specific, with estimates ranging from 900 t/km2/yr to 7 000 t/km2/yr (Rattan 1988). Likewise, studies of the economic impacts of soil loss are localized and varied, but are estimated to reach up to 9 per cent of GDP (UNU 1998). Loss of soil not only impairs productivity for future cultivation, but also causes: sedimentation in dams and rivers; smothering of aquatic and coastal habitats; and eutrophication. This, in turn, leads to reduced biodiversity in, and productivity of, these systems. Ultimately, these effects are felt in the lowered economic and nutritional status of African people.
Over the past 30 years, soil structure has been damaged, nutrients have been depleted and susceptibility to erosion has been increased, as a result of: increasing application of chemicals; use of inappropriate equipment and technologies; and commercial monospecific plantations
With appropriate agricultural practices, rates of soil loss can be reduced, and soil fertility and productivity can be restored, as recently shown in Ethiopia, Kenya, Malawi, Senegal, Somalia and South Africa (Nana- Sinkam 1995, Hoffman and Todd 2000). A Soil Fertility Initiative for sub-Saharan Africa was established in the 1990s, and launched at the 1996 World Food Summit, in response to growing concerns over soil degradation and loss. This is a participatory initiative, with technical partners including: the International Fertilizer Industry Association; the International Food Policy Research Institute (IFPRI); the International Centre for Research in Agroforestry (ICRAF); the International Fertilizer Development Centre; the Food and Agriculture Organization (FAO); and the WB. The approach combines policy reform and technology adaptation, aimed at conserving natural resources and improving farmer's livelihoods through the design and implementation of integrated plant nutrient management programmes, which use a combination of available organic sources of nutrients, supplemented by mineral fertilizers. Many countries are currently preparing National Soil Fertility Action Plans as part of this programme (Maene 2001).
Desertification describes an extreme form of degradation in dryland areas, caused by climatic and management factors, where the land is no longer productive. Some 66 per cent of Africa is classified as desert or drylands and, currently, 46 per cent of Africa's land area is vulnerable to desertification, with more than 50 per cent of that under high or very high risk (Reich and others 2001). The most vulnerable areas are along desert margins, as shown in Figure 2f.5. These areas account for 5 per cent of the land area, and are home to an estimated 22 million people (Reich and others 2001). Climate change is predicted to reduce rainfall, to increase evaporation, and to increase the variability and unpredictability in rainfall for many areas of Africa (IPCC 1998, IPCC 2001). This, in turn, will lead to greater vulnerability to drought and desertification. In combination with continuing pressure for economic growth, and the rapid population growth rates, across the region, this will further threaten food security, unless coherent land tenure and management policies are established and enforced.
In recognition of their vulnerability to declining land quality and desertification, African countries were largely instrumental in establishing the United Nations Convention to Combat Drought and Desertification in Countries Experiencing Serious Drought and/or Desertification, Particularly in Africa (UNCCD) in 1992 (UNCCD 2000). Since then, most African countries have embarked on National Action Plans, together with awareness-raising campaigns and, by 2001, 17 countries had completed and formally adopted their programmes (UNCCD 2001). Action plans have also been developed at the sub-regional level: in northern Africa by the Arab Maghreb Union (AMU); in western Africa by the Permanent Inter-State Committee for Drought Control in the Sahel (CILSS); in eastern Africa by the Intergovernmental Authority on Development (IGAD); and for southern Africa by the Southern African Development Community (SADC) (UNCCD 2001). A Regional Action Programme is also being developed, and will be coordinated by the African Development Bank (ADB) in Abidjan. Desertification, poverty, development pressures and climatic factors interact in a complex manner to influence food security. It is, therefore, essential that desertification be tackled within a development framework, and in a participatory manner. The approach must combine: political and legal reform; economic and social development strategies; land tenure reform; international partnerships; capacity building; and financial sustainability.
Figure 2f.5: Vulnerability to desertification in Africa
Source: Reich and others 2001