Impact of small-holder irrigation on the agricultural production, food supply and economic prosperity of a representative village beside the Senegal River, Mauritania

Abstract

A considerable effort to rehabilitate and extend degraded irrigation schemes is taking place along the Mauritanian side in the Senegal River Valley. To increase understanding of the effects of these activities on the population, a model was used to analyse how the irrigated agriculture production interacts with other production systems, human food supply, and economic prosperity in a representative village in the Middle Valley. The activities in the village comprise grazing of mostly goats and sheep on shrubland, rain fed cropping, partly on saturated soil as river or plain floods recede, and an irrigation area of 32 ha soon to be enlarged to 90 ha. The production environment is characterized by a long dry winter, small, highly variable summer rainfall, and high temperatures and evaporative conditions. River flooding is variable and dependant on rainfall at great distance from the village. Using a generated weather series, the model evaluates the fodder supply for livestock on the shrubland, the productivity of grain and stubble for human and animal consumption, respectively, together with the human labour, and fertilizer and fuel requirements to maintain optional production scenarios. A financial sector calculates cash balance. Established cropping practice uses cowpea, sorghum, millet and rice, the latter on irrigated land. All families have equal access to grazing on the shrubland but different access to rain fed, flood land, and irrigation cropping. The model evaluates the impact of production scenarios on identified family types with distinct resources, extending current practice to a more diverse use of irrigated land by introducing alternative summer (sorghum) and new winter (cowpea) crops. The analysis of the current scenarios reveals the small and variable productivity of the shrubland, the precarious situation facing a family with access to rain-fed cropping only, and the stabilizing, although still inadequate, impact of the initial irrigation project. Expansion of the irrigation area, and more diversified cropping, will provide more families with access to irrigation but the small area available to each family (0.50 ha) will not produce sufficient grain or straw unless cropping is intensified to include a second winter crop. With that, additional benefits will flow indirectly to villagers without access to irrigation, through increased requirement for labour and sale of grain and fodder. The expanded irrigation area increases the stock carrying capacity of the village, raising concerns for the sustainable management of the shrubland.