Simulating the growth and yields of Brachiaria Brizantha using the CROPGRO-perennial forage model under present and future climate conditions in subhumid environments of Ethiopia

Abstract

Brachiaria is a crucial forage crop in tropical and subtropical regions, but there is limited research on its response to climate change in Ethiopia. This study aimed to (1) calibrate and evaluate the performance of the CROPGRO-Perennial Forage model and (2) assess the impact of climate change on future Brachiaria brizantha yield in the subhumid environments of Ethiopia. Field data from Debre Zeit (Bishoftu) and Bako Agricultural Research Centers were used to calibrate and evaluate the model for accurately simulating rainfed growth and biomass yield. Weather data, including rainfall, temperature, and solar radiation, were obtained from Bishoftu and Bako weather stations. Historical and future climate scenarios for the near future, mid-century, and end of the 21st century were derived from the CORDEX Africa outputs under Representative Concentration Pathways (RCPs; RCP4.5 and RCP8.5). The calibration process involved refining parameters related to senescence and dormancy, vegetative partitioning, and N stress to improve the model's performance. Simulation results for future climate scenarios indicated an expected increase in biomass accumulation, with positive responses in the shoot, herbage biomass, and stem. However, leaf biomass and crude protein percentage of herbage are expected to decline. Overall, the production of B. brizantha is anticipated to increase in subhumid Ethiopian environments. Using simulations of CROPGRO-PFM can account for uncertainties about the impact of future climate change on Brachiaria grass. Further studies on Brachiaria forage responses under different management practices are advisable, to provide comprehensive information to policymakers and planners.