Response of corn and soybean yields to precipitation augmentation, and implications for weather modification in Illinois

Determining the feasibility of weather modification involves two questions: Is it possible to modify the weather and increase rainfall? Will weather modification benefit society? The work reported here is designed to answer the second question: Will weather modification in Illinois benefit agriculture? The objectives of the study were to learn how additional rainfall in typical dry, average, and wet summers would affect corn (Zea mays ) and soybean (Glycine max) yields, and the feasibility of different weather modification programs in actual Illinois summers. Two field studies were conducted during the summers of 1987-1991. The first was to determine how 25 percent rain increases during typical dry, average, and wet summers would affect corn and soybean yields. The other was to determine how increases of 10, 25, and 40 percent would affect yields. The results of the last study were used in a simulation study to evaluate the potential economic benefit of weather modification to Illinois agriculture. Results of the first field study show that both corn and soybeans will benefit from increased rainfall from weather modification. However, early-season temperature plays an important role in determining final yields. The second study showed that corn responded best to 40 percent rainfall increases to rain events greater than 25.4 millimeters. Soybeans yields were best with no additions to natural rainfall. The simulation study showed that economic benefit is greatest when weather modification is conducted using early-June season forecasts. This benefit is achieved even without perfect seasonal forecasts. Reference: Hollinger, S.E., and Changnon, S.A., Response of Corn and Soybeann Yields to Precipitation Augmentation, and Implications for Weather Modification in Illinois, Illinois State Water Survey, Champaign, Bulletin 73. Indexing Terms: Weather modification, corn, soybeans, Zea mays, Glycine max, precipitation, temperature. STATE OF ILLINOIS HON. JIM EDGAR, Governor DEPARTMENT OF ENERGY AND NATURAL RESOURCES John S. Moore, B.S., Director BOARD OF NATURAL RESOURCES AND CONSERVATION John S. Moore, B.S., Chair Robert H. Benton, B.S.C.E., Engineering Donna M. Jurdy, Ph.D., Geology H.S. Gutowsky, Ph.D., Chemistry Roy L. Taylor, Ph.D., Plant Biology Robert L. Metcalf, Ph.D., Biology W.R. (Reg) Gomes, Ph.D., University of Illinois John H. Yopp, Ph.D., Southern Illinois University STATE WATER SURVEY DIVISION Mark E. Peden, Acting Chief 2204 GRIFFITH DRIVE CHAMPAIGN, ILLINOIS 61820-7495