Improved management may alleviate some but not all of the adverse effects of climate change on crop yields in smallholder farms in West Africa

Abstract

Abstract The effect of climate change on crop yield in smallholder farms was simulated using the FAO s crop water productivity model AquaCrop and climate change projections from various climate models. This was performed for emission scenarios RCP 4.5 and 8.5 and for time horizons 2030 and 2050. Although the variation in inter-annual rainfall is projected to be substantial, the median projected change in total rainfall is predominantly slightly positive in future years. The climatic changes considered involve temperature increases of between 1.0\xa0°C (2030) and 2.5\xa0°C (2050), and an increase in evapotranspiration of between 3% (2030) and 7% (2050). An in-depth analysis was carried out in four pilot countries: The Gambia, Cote d Ivoire, Mali and Niger. Four crops and two cultivation methods were considered: irrigated tomato, rainfed sorghum, and rice and maize cultivated both under irrigated and rainfed agriculture. Projections show that if management practices are not improved, climate change will have a negative impact on agricultural production. On average, yield is expected to decline by 5 to 20%, depending on the crop, agro-ecological zone and time horizon. Simulations indicate that the cultivation of sorghum in the Sahelian zone may no longer be feasible under future climatic conditions. If management practices are not improved, the yield gap increases with climate change. To benefit from CO2 fertilization in future years, future soil fertility needs to increase by at least 15 to 20% in order to maintain current levels. Improved fertility management could lead to an increase in crop yields of between 5 and 14% for irrigated tomato and irrigated and rainfed rice. The impact of future climate changes on maize yield, maize being a C4 crop which benefits less from CO2 fertilization, was mostly negative even with improved soil fertility management.