Drip irrigating the gardens of the Sahel
Beside a busy main road leading out of the city of Ouagadougou, close to the Boulmiougou dam, a patchwork of small plots provide leafy vegetables to the city markets. Tiendrebeogo Hamado, previously a carpenter and builder who grew vegetables for only seven months of the year, now grows lettuces and cabbages year round. Whilst he retains his original trade, vegetable production has become his main economic activity. The secret of his success lies in a low-pressure drip irrigation system that greatly reduces the drudgery of hand-carrying water, whilst increasing water efficiency. And, like him, an increasing number of farmers across West Africa are adopting the system, known as the African Market Garden.
A healthy business
In the dry areas of Africa, market gardens are commonly the only form of irrigated agriculture. And with the rapid increase in urban populations, a rising number of consumers are demanding a greater variety of fresh vegetables and fruit. Supplying perishable produce to urban areas, these gardens can be the basis of a productive and profitable business.
Most gardens are irrigated by hand. In some areas surface irrigation is practised, but resulting salinisation of the soil is common. Poor water and nutrient management in these systems also results in low yields and poor quality of produce, and the expense of buying and fueling motorised water pumps is prohibitive for many farmers.
In ten countries across the region, however, the rising popularity of African Market Gardens is evident by the number of farmers who have received training in the drip-irrigation system, and have subsequently invested in it. Hamado trained at the International Crops Research Institute for Semi-Arid Tropics (ICRISAT) in Niger and is now a pilot farmer, training others in his home country of Burkina Faso. The key benefits, he says, are the reduction in energy required to irrigate his crops and the control he now has over the level of fertigation (adding fertiliser to the irrigated water).
A measured approach
To irrigate his plot, the water in the low-pressure system flows under gravity from a simple tank standing one metre above the level of the field. Fitted with a filter and a tap, the tank capacity is sufficient to cover a vegetable plot of 500 square metres. The exact quantity of water that the crop loses through evapotranspiration is delivered via a series of pipes laid on the soil along the crop rows. Small drip emitters in the pipes provide a constant drip of water, and the flow is controlled to prevent leaching of nutrients from the soil. Urea is added to the reservoir to allow delivery of water and fertiliser directly to the roots of the crop.
USAID has funded the irrigation equipment for projects in Burkina Faso and Ghana, although as a prerequisite for this support farmers must have sufficient land as well as the financial resources - approximately US$200 - to build the concrete reservoir tank. Despite this constraint, more than 250 systems have been put in place in three areas in Burkina Faso and Ghana and over 400 farmers trained. The project is due to end in September 2007 and the aim is to have 450 operative systems in Burkina Faso and Ghana, with further systems established across eight other West African countries: Cape Verde, Mauritania, Senegal, The Gambia, Guinea Bissau, Mali, Niger and Chad.
Growing without seasons
With improved water and soil management, crop yields are increased and production is extended even into the hottest, most arid Sahelian months (March to June). Provision of heat tolerant varieties of vegetable seed has also boosted farmers' yields. Noga, for example, is a variety of lettuce selected by ICRISAT that does not flower during high temperatures and is now grown by Hamado and other trained farmers in Burkina Faso. As a result, input use has decreased by almost a third, his yields have increased, and his profits have more than doubled. With increasing demand from his customers, Hamado plans to invest in a second reservoir to double the cultivated area under drip irrigation.
But Hamado does not own his land. As Iddal Sidi Mohammed, regional co-ordinator for the African Market Garden sub-regional programme explains, most of the land in the areas of Ouagadougou and Ouahigouya belongs to large landowners who divide it into small plots of 500 square metres, which they lease for 25,000 CFA a year (US $50). So despite Hamado's ambitions to expand his production, the only plot of land he can find is some distance away from the first, forcing him to build a second concrete tank. Yet even with this constraint, Hamado's experience and that of the other trained farmers suggests that through judicious use of water and fertilisers, African market gardens can support more people and provide a better income than before.
Date published: March 2007
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