Evaluation of climate change impacts and adaptation measures for maize cultivation in the western Uganda agro-ecological zone

In this study, we assessed the probable climate change impacts and the appropriate adaptation strategies for maize cultivation in the western Uganda agro-ecological zone. Detailed assessments were made using climate and crop models. The Statistical Downscaling Model (SDSM) v4.2 was used to downscale low resolution future climate data obtained from general circulation model HadCM3 for two SRES scenarios, A2 and B2. The CERES-Maize crop model of DSSAT v4.0.2.0 was used to simulate maize yield for the assessment of climate change impacts. In the western Uganda agro-ecological zone, the annual average temperature is expected to increase by between 0.69-2.46 and 0.66-1.78 A degrees C under the A2 and B2 SRES scenarios, respectively, in the three future periods of 2020s, 2050s, and 2080s relative to the base period (1961-1990). Monthly average temperatures are expected to increase for most of the months but will slightly decrease for the month of November under both scenarios. The annual average rainfall is expected to decrease by between 4.7-16.4 and 4.7-11.8 % under the A2 and B2 scenarios, respectively, in the three future periods. Monthly average rainfall is expected to decrease for most of the months but will increase for the months of October, November, and December under both scenarios. Crop modeling results show that in the March-May crop season, maize yields will decrease by between 9.6-43.3 and 10.5-28.4 % under the A2 and B2 scenarios, respectively, relative to the base period in the three future periods. However, in the September-November crop season, maize yields are expected to increase by between 8.1-9.6 and 8.6-10.2 % under the A2 and B2 scenarios, respectively. Supplementary irrigation and shifting of planting dates are found to extenuate the impacts of future climate on maize yields. Irrigation application of 80 mm during the growing season in the March-May season is expected to increase maize yields by as high as 42.1 % under future climate, while planting 16 days earlier than the current planting date in the same season is expected to increase maize yields by as high as 17.9 %.