Changes in Soybean Yields in the Midwestern United States as a Result of Future Changes in Climate, Climate Variability, and CO sub(2) Fertilization

The US produces over 50% of the world's soybean production, making it one of the nation's most important crops. In this study, soybean growth was modeled at nine representative farm locations across Illinois, Indiana, Ohio, Michigan, and Wisconsin using seven climate scenarios: the current climate, two future climates based on mean climate changes, and four climate variabilities. The impact of carbon dioxide fertilization was also considered. The SOYGRO model was selected as the crop model. Results showed that, under the future climate scenarios, the central and northern locations of the region exhibited large increases in soybean yields, while the southern locations experienced yield declines. Carbon dioxide fertilization produced a soybean yield increase of approximately 20%, but when extreme climate-change scenarios were used, all locations in the region experienced soybean yield decreases due to high temperatures and/or moisture stress. Increasing the variability of the future climate scenarios decreased the mean decadal crop yields.