A Projection of Maize-Yield Potential in the Southwestern United States

Abstract:

As human population is projected to increase by 35% by 2050, agricultural production requires substantial growth compared to the current yield levels. In the coming decades, evaluating yield potential (Yp), the yield of a crop cultivar when grown without limitation of water and nutrients with effectively controlled pest and diseases change and solely determined by climate variables, is crucial to assess food security under climate change scenarios as it is directly connected to amount of exploitable yield. In this study, Yp is estimated and projected using regional climate models (RCM) and a process-based crop model over the Southwestern United States. High-resolution (8km grid spacing at the inner domain) climate variables are obtained using dynamical downscaling with two RCMs (WRF and OLAM) driven by boundary conditions from a GCM (GFDL-ESM2M) in the 5th phase of Coupled Model Intercomparison Project (CMIP5) archives. 20 years of the high-resolution and bias-corrected climate data from the two RCM runs (historical (1981-2000) and future (2031-2050)) are employed on the process-based crop model, Agricultural Production Systems sIMulator (ASPIM) to assess the climate change impact on maize Yp. The potential maize yield in the future period under the RCP8.5 greenhouse gas concentrations pathways shows that the yields are significantly changed when compared to the historical period. In the generally rising temperature regime, the projected Yp shows strong geospatial variations according to the regional climate characteristics in the high-resolution RCM projections.