Evaluation of the Relationship and Impact of Climatic Factors on West Tennessee Corn and Soybean Yields from 1955 to 2013

This study was designed to determine if a relationship existed between corn (Zea mays) and soybean (Glycine max) yields and climate factors in West Tennessee from 1955 to 2013. Yield data was obtained from National Agricultural Statistics Service (NASS) annual crop surveys for the twenty one counties in United States Department of Agriculture (USDA) West Tennessee and Delta Districts. Climate data was obtained from National Climatic Data Center (NCDC). Only climate data from April through October was used in calculations to more accurately reflect corn and soybean growing seasons. Correlations, linear regressions, and multiple regressions were developed to compare crop yields with climate factors for the year as well as three phases of the crop production process (planting, growing, and harvesting). Significant relationships were found to exist between corn yield and minimum temperature (r = 0.32; P = .01), precipitation (r = 0.29; P = .26), Palmer Z-Index (r = 0.26; P = .47), and one month Standardized Precipitation Index (r = 0.26; P = .049). Significant relationships were found between soybean yield and maximum temperature (r = -0.32; P = .01), precipitation (r = 0.43; P < 0.001), Palmer Drought Severity Index (r = 0.28; P= .03), Palmer Z-Index (r = 0.43; P < .001), and one month Standardized Precipitation Index (r = 0.46; p < .001). The study found that yields were dependent on multiple climatic factors due to the abundance of significant multiple regression models compared to linear regression models. However, West Tennessee corn and soybean yields were not statistically influenced by average temperature or climate factors during the planting stage of production. Overall, growing season temperature and precipitation factors were important and will continue to impact corn and soybean yields in West Tennessee.