Quantifying the Impact of Changes in Atmospheric Vapor Pressure on Maize and Soybean Yields

Vapor pressure deficit (VPD) is expected to increase under several global scenarios. Increasing VPD will increase the atmospheric demand for water vapor and potentially water usage by crops. As a result, changing VPD and crop water use may affect crop yields in the near future. Quantifying the relationship between VPD and yield output is critical to improve crop model simulations in the context of global change. To address this problem, we conducted simulations using a mechanistic modeling program called Agro-IBIS (Integrated BIosphere Simulator – Agricultural version). Modeling simulations were forced with NARCCAP (North American Regional Climate Change Assessment Program) weather data for the years of 1970-2000 and 2039-2069 to analyze the past and predicted climatology for the future years to come, respectively. Preliminary analysis indicates that maize and soybeans shows a correlation between VPD increase and yield decreases for the future years included in the analysis. The finalized results of this analysis are still to come with the hope of estimating future yield outputs, identifying the relationship of VPD increases with global warming, and closing knowledge gaps.