A Mesoscale Study of Corn-Weather Response on Cash-Grain Farms

Abstract

Weather records for 49 locations and detailed agronomic data from 60 farms in a 400-mi2 area in central Illinois were used to study corn-weather relations exhibited by actual farming operations in a typical agricultural area of the American Corn Belt. Weekly, monthly and seasonal rainfall and temperature values plus agronomic data were correlated with corn yields during 1955?1963. The results are of added importance because the data sample was from a period when new agronomic practices, which could alter corn-weather relationships established in previous studies, were being widely employed. July and August mean temperatures and cumulative degrees above 90F during July and August had the strongest correlations with corn yield, ?0.50, ?0.69 and ?0.51, respectively. July rainfall had a stronger association with yields than rainfall in any other month, but it was considerably less than the association for July temperature. Weekly rainfalls and temperatures in early June and early August correlated moderately well with yields, a finding that does not agree with those from certain other corn-weather studies. Several weather variables were more highly correlated with corn yield than were any of the newer agronomic practices generally considered to be important factors relating to corn yields. A trend of increasing yields with time during the 9-yr period was related to steady improvement in technological practices and also to a trend for better (cooler) corn weather in July and August. In general, the results indicate that corn-weather relations defined by data from cash-grain farms during a recent 9-yr period of technological change are somewhat different from those defined in earlier studies using either experimental farm data or regional average yield data.