Impacts of the COVID-19 economic slowdown on soybean crop yields in the United States

It is without question that the COVID-19 pandemic has taken its toll on the U.S. economy. Stay-at-home orders led to reduced vehicular traffic and widespread declines in anthropogenic emissions (e.g., nitrogen oxides (NO_x)). This study is the first to explore the potential consequences of O₃ changes resulting from the economic shutdown in the United States on soybean crop yields for 2020. The pandemic's impact on surface O₃ is quantified using the NOAA's National Air Quality Forecasting Capability (NAQFC), which is based on the Community Multi-Scale Air Quality (CMAQ) model for May-July 2020. The "would-be", 2020 level business-as-usual (BAU) emissions are compared to a simulation that uses representative COVID-19 (C19) emissions. For each emissions scenario, crop exposures are calculated using the AOT40 cumulative exposure index and then combined with county-level soybean production totals to determine regional yield losses. Exposure changes ranged between - 2 and 2 ppmVhr^-1. It was further shown that increased exposures (0.5 to 1.10 ppmVhr^-1) in the Southeast U.S. counteracted decreased exposures (0.8 to 0.5 ppmVhr^-1) in the other soybean-producing regions. As a result, corresponding yield improvements counteracted yield losses around the Mississippi River Valley and allowed for minimal improvements in soybean production loss totaling $6.5 million over CONUS.