Effects of Natural Climatic Fluctuations on the Temporal and Spatial Variation in Crop Yields

Abstract

An investigation was made of variations in corn and soybean yields resulting from natural fluctuations in weather conditions between years in a five-state area in the Midwest. Analyses were performed for crop districts within each state and for various combinations of the five states when crop yields are evaluated over periods of 1-5 years. Results were presented in the form of temporal-spatial probability distributions, in which the distributions were based on deviations from “expected” yield after adjustment for technology advancements during the period of record (1931-75). In general, it was found that weather-related deviations in corn yield were greater than in soybeans, a decrease in temporal variability occurs from west to east, negative deviations tend to be greater than positive deviations, but that the five-state area seldom experiences large deviations from expected yield and the occasional large deviations do not usually persist long.