Modelling the effect of field management measures on crop yield and implications for food security and virtual water trade in the Volta basin countries, West Africa

Hunger and malnutrition continue to claim thousands of lives in developing countries. With population growth and water scarcity, increasing food production is not only crucial in meeting current and future food demands but also necessitates the production of more food per drop of water and supplementing water deficit through virtual water trade (VWT). In the Volta Basin countries, agriculture is mostly rain fed on nutrient poor soils. In this study, a GIS based Environmental Policy Integrated Climate model (GEPIC) is used to assess the impact of irrigation and fertilizer on crop yields and crop water productivity (CWP) of maize, millet and sorghum. The investigations reveal yield increment in different magnitudes with alternative levels of water and fertilizer inputs. However maize and millet do not respond significantly to the provision of irrigation alone, but response highly to additional fertilization, implying that fertilizer is a major limiting factor to the growth of these crops in the region. An investigation into water-food relations showed that any measure which increased yield leads to an increment in CWP. Meanwhile VWT analysis revealed that all the countries with the exception of Burkina Faso are net importers of maize but almost self sufficient for millet and sorghum. The food import is mainly from outside of the region whereas the trade between the countries in the region is rather smaller. With the population growth and the increase in food demand, it is expected that the virtual water import will increase. It is important for the Volta Basin countries to adopt a strategy that involves cultivation of crops of high water productivity and yield and promote intra-regional virtual water trade to more efficiently utilize the local water resources. The findings call for emphasis on rain fed agriculture with greater attention on improving soil fertility as means to improve food security