Projection and attribution of future maize yield changes in the US Corn Belt

Climate change is anticipated to progressively affect crop yields and may already be doing so. The United States is the world’s largest producer and exporter of agricultural commodities, where most crops are produced in the Midwest Corn Belt. Hence, the future crop yield changes in the Corn Belt could have broad implications for world food market. This study focuses on future yield projections for maize, an important food, feed and fuel crop in the Corn Belt highly influenced by climate variables. To simulate the future maize yields in the Corn Belt under the changing climate, we employed statistically downscaled (4km) climate output from an ensemble of eight General Circulation Models (GCMs) under RCP8.5 to force a process-based spatially-distributed crop model, the Decision Support System for Agrotechnology Transfer (DSSAT). To understand the projected yield trend and quantify the contribution of different factors to future changes, major drivers for yield variation and change are investigated, including water, temperature and nitrogen stresses, and the role of CO₂ concentration is identified based on sensitivity experiments. Results from this study help reveal the key limits on crop growth in different stages and support the long-term planning and mitigation strategy development.