Evaluation of Potential Effects of Weather Modification on Agriculture in Illinois

Abstract

An investigation was made of the potential effects of modifying growing-season rainfall on the yields and economic benefits of the two major Illinois crops, corn and soybeans. Crop yield and weather data for the 38-year period, 1931–68, were used to develop multiple regression equations relating crop yield to technology trends and various temperature and precipitation parameters. This was done for each of 13 regions with similar yield characteristics. Hypothetical seeding models were then used with the appropriate regional equation to evaluate the effects of seeding-induced changes in July-August rainfall on crop yields. Frequency distributions were developed to define expected gains or losses from seeding with each hypothetical model under assumed seeding operations lasting 1, 2, 3 and 5 years. Results indicated that in most regions of Illinois, corn and soybean crops would be benefited in the majority of the growing seasons through a cloud seeding program. Reaction to the potential seeding was found to vary substantially between regions with the same seeding model. Furthermore, seeding effectiveness may vary considerably from year to year with the same model in the same region due to the temporal variability in daily rainfall distribution characteristics.