Climate change and soybean production: A regional evaluation in the Northwestern part of Türkiye

Climate plays a crucial role in the growth and development of soybean. The objectives of the study were to calibrate and evaluate the DSSAT-CROPGRO-Soybean and project future soybean production in Bursa, the northwestern part of Türkiye, under different cultivars and planting dates using climate projection data. The model was calibrated for two soybean cultivars, A3127 and 1530, belonging to different maturity groups. Soybean yield was determined by GFDL-ESM2M, HadGEM2-ES, MPI-ESM-MR global climate models, and RCP4.5 and RCP8.5 representative concentration pathways. Results were evaluated under three periods: the reference period (1971–2000), the near future (2040–2069), and the far future (2070–2098). To comprehensively evaluate the impacts of climate change, yield was predicted for two different maturity groups under two different planting dates (April 30 - May 15). According to the study results, rising temperature leads to a shortening of the time to maturity for both cultivars. This will provide some benefit to late-season planted soybean production. An increase in carbon dioxide (CO2) concentration enhances soybean yield. The predicted increase in soybean yield ranges from 17 % to 38 % according to the RCP4.5 scenario and from 12 % to 53 % according to the RCP8.5 scenario. Planting soybean on May 15 instead of April 30 also slightly increases yield. According to the results of water productivity, a decrease of 1 to 7 % in the HadGEM2-ES global climate model and an increase up to 10 % was observed. In comparison, other models predicted an increase from 14 % to 38 %. In the future, soybean cultivation in this region is expected to benefit from the increasing CO2, which may partially offset the negative impacts of projected high temperature. However, as seen in the HadGEM2-ES model, the effectiveness of these offset decreases under extreme temperature increases, where heat stress exceeds the physiological benefits of CO2.