Short-term Climate Variability Impacts on Regional Crop Yields in Missouri

An analysis of crop yields for the state of Missouri was completed to determine if an interannual or multidecadal variability existed as a result of the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). Four crops were of focus for this study over a period of up to 94 years. Corn, sorghum, soybeans, and wheat yields were recorded in bushels per acre, from the USDA National Agricultural Statistics Service, for each of the six climate regions of Missouri, defined by NOAA. Analysis using periodograms demonstrated interannual, interdecadal, and mulitdecadal variations in crop yields. Interannual variations represent a correlation to ENSO phase, interdecadal variations represent a possible “interaction harmonic” between ENSO and PDO, and mulitdecadal variations represent a correlation to PDO phase. The two northern Missouri regions displayed the highest variability related to ENSO and PDO. Regions 3 and 5 showed all crops having interannual variability, while regions 4 and 6 displayed both interannual and interdecadal variability with all crops. Corn and soybeans represented the greatest response to both ENSO and PDO phases; and for all regions, they displayed a relationship to annual temperature and precipitation. For instance, in the years 1980 and 2012, both crops displayed a sharp decrease in yield, most likely due to excessive heat and drought. For regions in contact with the Missouri and Mississippi Rivers, all crops exhibited a decrease in yield for years of abundant precipitation resulting in flooded rivers. Examples include 1986 and 1993, which were years of positive PDO with transitions of ENSO phase from neutral to El Niño.