ESTABLISHING THE CURRENT AND FUTURE PROJECTED SUITABILITY OF SORGHUM PRODUCTION UNDER CLIMATE CHANGE SCENARIOS IN EASTERN UGANDA

Abstract

This study aimed at investigating the extent of the current and future projected suitability of sorghum production under climate change scenarios in eastern Uganda. The study used historical observed rainfall data (1985 to 2015) for Soroti and Serere stations, Sorghum yield downloaded from FAOSTAT database for study period (1985-2015). Observed Seso 1 (M91057) and Seso 3 (SRN 39) sorghum varieties yield across the zone for three seasons (2014B, 2015A, 2015B) were obtained from National Semi-Arid Agro technology Research Institute. The study also analyzed rainfall outputs from one CORDEX RCM, namely the Rossby Centre regional atmospheric model (RCA) (Samuelsson et al., 2011). This model was used to dynamically downscale historical and future CGCM outputs under radiative forcing storylines of Representative Concentration Pathways (RCPs) 4.5 and 8.5 scenarios for greenhouse gases trajectories for the period 1950–2100 at a spatial grid resolution of 0.44°. The data was subjected to graphical and trend analysis whose significance was evaluated using the Mann-Kendall test in order to determine the climate variability, change signals and sorghum yield change patterns.

The results indicate that there will be a general increase in annual rainfall in Eastern Uganda. For seasonal rainfall over Eastern Uganda under both RCP 4.5 and 8.5 scenarios; there will be a change in seasons is expected over Eastern Uganda, where the MAM season which used to be the major and more favorable season will become the minor one, while the SON season which used to be minor will become the major one for Sorghum production.

There will generally be an increase in sorghum grain yields under both climate change scenarios, thus the study area is expected to have great potential for sorghum production. However, for a few years, there will be a reduction in the grain yields under both climate change scenarios for RCP 4.5; 2048 (724.3%), 2019 (-17.1811) and RCP 8.5; 2026 (-21.1%), 2047 (74.3%). It is also evident that the last decade (2040-2050) will be more suitable for sorghum production as the highest figures of yield are predicted in the area under all climate change scenarios.

The study provides critical science-based evidence of climate variability and change over Eastern Uganda. It contributes to the understanding of the linkages between sorghum productivity and observed rainfall and provides information on the future suitability of sorghum crop production under different climate change scenarios. The results from the study are therefore, pointers for the development of coping and adaptation strategies to expected climate extremes to improve sorghum productivity, promote the incomes of farmers and enhance food security for sustainable development in Eastern Uganda and country at large.