Drylands in Sub-Saharan Africa

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The drylands of Sub-Saharan Africa harbor great cultural and biological diversity, which are valuable resources for building sustainable rural livelihoods. But these areas are also highly vulnerable to the climatic and other hazards that trigger desertification. For example, over the last four decades, the continent has suffered seven major episodes of drought. In two key regions - the Sahel and the Horn of Africa - the droughts of 1972-74 and 1981-84 caused massive social disruption and human suffering.

Large-scale efforts to avert desertification in sub-Saharan began during the 1950s under colonial regimes, prompted by concerns that agricultural practices in drylands might lead to a catastrophe similar to North America's Dust Bowl. Those initiatives failed, however, mainly because they were highly centralized and technocratic; made unrealistic assumptions about labor and access to inputs and capital; and failed to involve rural communities in planning.

By the 1980s and 1990s, researchers had begun to question the assumption that rampant land degradation is driven unwittingly by the activities of small farmers. They came to realize that these growers are quite aware of the problem and have developed methods to combat it, such as water-harvesting techniques in Sudan and the use of holes to hold water and manure in the root zone of plants for rehabilitating eroded lands in Burkina Faso. But increasing population pressure is overwhelming traditional systems, forcing farmers to shorten fallow periods and extend cultivation onto unsuitable lands. As soil fertility declines, farmers are unable to restore it, since they cannot afford to buy fertilizer.

In recent years researchers have gained greater insight into the complex interactions between the economic, social and climatic factors driving desertification. On this basis, they have opted for more holistic development approaches that focus on policies and institutions as well as technological interventions.

Selected Highlights from Research for Dryland Development

Hardy dryland staples: Pearl millet, the most inherently drought-tolerant of all the major staples, together with sorghum, are key cereal grain crops in the drylands, providing food, feed and, in the case of millet, fuel and construction material as well. Despite formidable obstacles to improvement of these crops for drylands, plant breeders at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and in national partner organizations have made important gains. In southern Africa, for example, about 34 percent of the total millet area is now planted to improved materials and 23 percent of the sorghum area. Altogether, about a million hectares are being sown to new millet and sorghum varieties.

Early maturing varieties of these crops have proved especially useful for helping dryland communities get through the "hungry season." This is the period before harvest, when the previous year's grain supplies have been exhausted. The millet variety 'Okashana 1', for example, which was selected by farmers in Namibia and matures 4-6 weeks earlier than traditional varieties, spread in just a few years during the mid-1990s to cover half the country's millet area. The US$3 million investment required to develop and disseminate the variety was estimated in 1998 to be yielding extra grain worth $1.5 million annually.

Fertilizer micro-dosing: A variety of new practices are better enabling farmers in Africa's Sahel region to raise soil fertility. Organic matter and nutrient content are generally low in this region, because growth of vegetation is limited and much of it is removed for feed, fuel and construction. There is ample evidence, though, that fertilizer can boost the productivity of dryland agriculture when rainfall is adequate. But applying normal doses of fertilizer is too expensive for most farmers in the Sahel and besides increases the risk of soil acidification. The use of organic matter, in the form of livestock manure and crop residues, is effective, but supplies of these materials are limited.

A safer and more economical alternative is to apply small quantities of inorganic fertilizers in the hole where seed is sown, a practice called "micro-dosing." The approximately 5,000 farmers now using this practice in Niger find it helpful to measure out tiny doses of fertilizer to their crops, using soft drink bottle caps. Micro-dosing helps crops mature more rapidly and escape the worst effects of drought. Yield increases across Niger range from 50 to 100 percent. This and other options are the focus of collaborative research involving ICRISAT, the International Center for Tropical Agriculture (CIAT), the International Food Policy Research Institute (IFPRI) and their national partners.

Crisis mitigation in livestock systems : In the Horn of Africa, traditional pastoralism is under pressure, as populations increase, urban areas and roads encroach upon pasturelands, and these lands are converted to crop production and wildlife reserves. Frequent droughts further aggravate those pressures.

Pastoralists and agro-pastoralists in the region are highly dependent on livestock, which provide up to 70 percent of rural incomes. The International Livestock Research Institute (ILRI), in collaboration with the Animal Agriculture Research Network of the Association for Strengthening Agricultural Research in Eastern and Central Africa (ASARECA), is conducting research to better understand how people in dry areas cope with drought, animal diseases and other stresses and how their strategies can be strengthened. In a survey of critical areas along the Ethiopia-Somalia border, scientists using geographical information systems (GIS) technology are constructing a detailed picture of infrastructural, relief-resource, security and food-security conditions. They are also employing participatory methods with pastoralists to better understand the social and biophysical constraints of their livestock systems.

The Desert Margins Program: Since 1993 the CGIAR Centers have contributed to the development of the United Convention to Combat Desertification (UNCCD), which places particular emphasis on Africa. An important product of that partnership is the Desert Margins Program (DMP), which unites nine countries straddling Africa's desert margins - Botswana, Burkina Faso, Kenya, Mali, Namibia, Niger, Senegal, South Africa and Zimbabwe - with four CGIAR Centers: ICRISAT (which convenes the program), ICRAF, ILRI and CIAT. The program's goal is to help arrest land degradation through improved agricultural practices (www.dmpafrica.net). One recent product of the program's work is a major collaborative study that documents the effects of land degradation on biodiversity loss across dryland Africa.