An assessment of USDA corn condition ratings across the US Corn Belt

Changes in temperature, precipitation, and adverse weather across the U.S. Corn Belt associated with anthropogenic climate change may have an effect on corn (Zea mays L.) condition ratings in one of the leading corn production regions in the world. Using USDA National Agricultural Statistics Service data, this study aims to quantify the correlation of corn condition ratings with climate variables and yield, understand intergrowing season behavior of corn condition ratings, and quantify spatiotemporal trends of ratings across the U.S. Midwest (1986-2020). With an existing statistically significant (95% confidence level) correlation between corn condition ratings, Palmer drought indices, precipitation, temperature, and detrended corn yield, it is validated that qualitive rating data should be further examined. Using the Crop Condition Index (CCI), corn condition ratings supportive of positive yield prospects subtly decrease from June to September on average. The CCI values increased within June (ranging from 0.08 to 0.40 CCI yr(-1)),but subtly decreased within July and onward throughout the Midwest (ranging from -0.02 to -0.62 CCI yr(-1) over the past 35 yr. From an interannual perspective, corn condition ratings supportive of extreme degrees of yield loss have significantly increased in 7 of the 12 Midwest states (ranging from 0.15 to 0.30% yr(-1)). Thus, increasing yields despite decreases in corn condition ratings suggests crop advancements such as hybrids and management have offset environment challenges with corn quality. These advancements need to be a continuing effort under a changing climate given rating trends, and corn condition ratings can provide essential risk assessment information for corn producers and other stakeholders.