Impact of climate change on soil water balance, maize production, and potential adaptation measures in the Rift Valley drylands of Ethiopia

Abstract

The dominant effect of climate change in Africa will be in altered water balances. The objectives of this study were: 1) to assess the impact of climate change on soil water balance and maize production, 2) to evaluate the effect of tied-ridges and increased fertilizer use as potential adaptation options during 2021–2050 & 2066–2095 periods. The MarkSimGCM daily weather generator was used to generate projected climate data using the outputs from ECHAM5 and ensemble mean of six GCMs. AquaCrop model was used for modeling soil water balance and evaluating adaptation options. During the 2021–2050 & 2066–2095 projection periods, the maize growing season (March–September) reference evapotranspiration (ETo) increased by 5% and 14%, respectively. During the two projected periods, there was a decrease in runoff & transpiration and an increase in evaporation. The maize yield projected to decrease by about 9% during both periods. The combined effect of tied ridges and increased fertilizer under elevated CO2 concentration increased the crop yield by almost 90% during the 2021–2050 climate projection periods. The yield increase was a result of decreased evaporation and runoff and an increase in transpiration from tied ridges and increased soil fertility as well as carbon dioxide (CO2) fertilization effect.