Impacts of Weather and Climate On Corn and Soybean Production In the Midwestern USA, 1900-2010.

Weather and climate have had major influences on crop production in the Midwestern USA region during the past century.  The objective of this study was the identification of climatological impacts involved with the production of two major crops commonly grown in the region: maize (Zea mays L.) and soybean (Glycine max (L.) Merr.)] during the period 1900-2010.  Process-based crop simulation models were used to simulate crop growth, development and yield of the two crops while holding all input variables except weather constant.  Regionally, low precipitation and moisture stress were chief limitations to simulated crop yields. Simulated maize and soybean yield series were found to increase with time since the late 1930's at most of the study sites. These increases were associated with increased precipitation and plant available soil moisture.  The study suggests that at least part of the observed yield increases in the region during recent decades have occurred as the result of wetter, less stressful growing season weather conditions.