Modelling soybean yield response to nutrients applications under projected climate change scenarios in Benin

Climate and its variability is a major risk factor for the success of soybean cultivation in Benin. This aspect becomes even more important in the context of future climate scenarios, in which global warming is predicted and food security is under threat. This study evaluated the influence of future climate on soybean yield under fertilizer application considering the period (1980-2018) and future (2018-2079) climate scenario. The study applied DSSAT and the climate data projected from CORDEX to simulate the trends of crop yields for soybean in two agroecologicals zones in Benin by 2079 under different climate change circumstances (RCP 4.5 and RCP 8.5), based on a 2-years experiment established at Ouesse and Bembereke. Two fertilizers (NPKMgZn) practices were applied: 14-23.9-18.18-11.45-4.14 and 16.6-23.5-29-15.2-7.7. Our findings indicated that the CROPGRO model can accurately (R2 > 0.70) simiulate soybean yields while NRSME values varied between 11.05 % and 22.8 %) in simulating soybean yields in both sites. This shows the ability of the CROPGRO model to simulate yields under a wide range of environmental conditions. Simulations carried out with different climate scenarios have shown that soybean yields will likely decrease from 9% to 19% for scenario RCP 4.5, and 22 % to 31%, respectively, by the middle of the century with the application of fertilizer doses. The study suggests that a readjustment of specific nutrient doses will be necessary by the end of the century to ensure good soybean production under future climatic conditions. Keywords: Benin, climate change, DSSAT, fertilizers, legume, simulation, soil fertility