in proportion of irrigated arable land and its contribution to total food production. In terms of value, irrigation is responsible for an estimated 9% of the crops produced in SSA (Yudelman, 1994). Irrigation development in SSA was initiated during the colonial period with the construction of irrigation schemes by private companies from Europe in the major river basins and also in the inland valleys for the production of tropical fruits and vegetables for European markets. After independence, public sector irrigation schemes have been accompanied by a growing number of new initiatives by private sectors. The management of the irrigation systems is generally ensured jointly by the state, as regards the primary infrastructure or public systems and by users associations for the secondary and tertiary infrastructure, or by private systems. The disengagement of the state from the irrigation sector since the 1980s and the subsequent creation of user associations (in place or planned in South Africa, Burundi, Côte d’Ivoire, Ghana, Madagascar, Mali, Mauritius, Niger, Nigeria, Senegal, Swaziland and Zimbabwe), as well as the more recent promotion of participatory approaches (Burkina Faso, Mauritania and Chad) concerns about 20 African countries. The example of Kenya illustrates the choice of management transfer; all new irrigation schemes created between 1992 and 2003 are private, while some former public schemes are still partially administered by the state.

Most large-scale irrigation schemes and soil conservation projects attempted in sub-Saharan Africa in the past have met with little success (Bonkoungou, 1996). They have generally been expensive to construct and maintain and their performance has been disappointing. Not only have production increases been lower than anticipated, but systems have often been unsustainable, due to low output prices and high operation and maintenance costs. Examples include the Office du Niger in Mali, the Awash Valley scheme in Ethiopia and the Jahalya Pacharr scheme in the Gambia. Countries that have already developed their irrigation potential, such as South Africa, no longer carry out construction work, rather, they have undertaken the development of more efficient techniques for water use (sprinkler and localized irrigation) with the aim of reducing the water volume used for crops (AQUASTAT, 2005).

Yet water management is less advanced in sub-Saharan Africa than in any other developing region. The percentage of arable land that is irrigated is about 4.0% compared to 37% in Asia and 15% in Latin America. This figure that rises to 7% in Africa as a whole given that 40% of the total irrigated area is in North Africa (NEPAD, 2003). The irrigated area in SSA is concentrated in South Africa (1.5 million ha) and Madagascar (1.1 million ha). Nine other countries (Nigeria, Ethiopia, Mali, Somalia, Tanzania, Zimbabwe, Senegal, Zambia and Kenya) each have more than 100,000 irrigated hectares. About half of the irrigated areas are small-scale systems. Equatorial Guinea has no irrigation because of the climate conditions. In 2002, Madagascar had about 1,086,000 ha of irrigated areas representing 30.6% of total cultivated areas. Water is collected mainly from dams, or diversions from rivers or channels and dispatched by gravity. In 2000, irrigated rice with total or partial water control had grown to over 1,062,000 ha, representing about 75.8% of total rice areas. Other irrigated cultures are cotton

(0.11%) and sugar cane (0.22%). About one third (28.2%) of the irrigated rice areas are traditionally managed i.e., by family groups, without government intervention. They are scattered in the inland valleys and each perimeter rarely extends over 10 ha (FAO, 2005a). This irrigation system is similar to Asian farming practices. Irrigation water is essential for puddling the rice field while drainage is needed for avoiding rice plant withering. Vegetables are grown after rice using residual soil moisture.

One way forward is to effectively build on local knowledge, institutions and solutions for better water management such as integrated water resources management and the development of small-scale irrigation. Some policies and legislative proposals include integrated water resources management schemes, which, accompanied by practices that protect water resources, could help to guarantee their long-term sustainability. With regard to the number of smallholder farmers in sub-Saharan Africa, different stakeholders (governments, public sector, private sector, NGOs, farmer organizations, etc.) could work to improve the efficiency of traditional, small-scale systems by maximizing available rainfall and soil management strategies that build water holding capacities, promote greater water infiltration and percolation, reduce runoff and decrease evaporation through mulching and conservation tillage. Madagascar is
one of the leading countries in sub-Saharan Africa in achieving irrigation potential (Yudelman, 1994). Many of the irrigation systems in Madagascar have Asian farming components and such systems may be relevant to and beneficial for other SSA countries.

2.1.2 Crop genetic resources
Small-scale farmers traditionally exchange seeds among themselves. This system of seed exchange prevailed in the past and was an efficient way to release crop varieties and spread agricultural knowledge.

Like in other parts of the world, cereals are the most important food crops; however, the sub-Saharan region also has its specificities. Crops grown in the region may be classified as cereals (maize, sorghum, rice, millet (Pennisetum glaucum), pulse (beans, cowpeas, chickpeas, pigeon peas), oil crops (groundnut, soybean), roots and tubers (cassava, sweet potato, yam, potato) and tree crops such as plantain and banana. Cassava, yam and plantain are staple food crops essential to food security in the humid and subhumid tropics of Africa (Asiedu et al., 1992). Commodity priority is varying at the sub-regional level; the order of priority could be based on the number of countries citing the commodity and the priority rank they give to it (ASARECA, 2006a). Among cereals, millet and sorghum are common in drier areas of the northern part of SSA and wheat is mainly
grown in the eastern subregion (Kenya, Tanzania, Uganda) and in South Africa, with teff in Ethiopia. Rice has become increasingly important in the SSA region, both as a food source and as an economic commodity and is now the most rapidly growing food source in Africa (WARDA, 2003). In Madagascar, rice is the staple food and is eaten three times a day as the main ingredient (IRRI, 1993). Among legumes, which are usually grown in mixed cropping systems in the SSA, cowpeas are mostly found in the western sub-region mainly with sorghum and millet (Singh et al., 1992), while