WEATHER IMPACTS ON MAIZE, SOYBEAN, AND ALFALFA PRODUCTION IN THE GREAT LAKES REGION, 1895-1996

Authors: ANDRESEN, J - MICHIGAN STATE UNIVERSITY; ALAGARSWAMY, G - MICHIGAN STATE UNIVERSITY; Rotz, Clarence - Al; LEBARON, A - MICHIGAN STATE UNIVERSITY

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2001
Publication Date: 11/20/2001
Citation: Andresen, J.A., Alagarswamy, G., Rotz, C.A., Lebaron, A.W. 2001. Weather impacts on maize, soybean, and alfalfa production in the great lakes region, 1895-1996. Agronomy Journal. 93(5):1059-1070.

Interpretive Summary: Weather remains among the most important uncontrollable variables involved in crop production. Analyses of the impact of weather and climate on agriculture over extended time periods are constrained by the lack of long- term field experiments. Also, isolation of the impact of weather is difficult because technological improvements in agriculture (e.g. improved varieties and increased rates of fertilization) have resulted in significant yield increases during the past century. An alternative strategy is the use of crop simulation models, which are based on the underlying physiological processes governing plant growth and development. Simulated crop growth was used to study the impact of weather and climate on typical crops grown in the Great Lakes region over the past 100 years without the influence of technological improvements. Simulated maize and soybean yields were found to increase with time since the late 1930's at most of the study sites due to increased precipitation and more humid conditions. No consistent trends were found for alfalfa. The simulated yields support previous research identifying a period of favorable climate for crop production in the region from 1954-1973. The study suggests that at least part of the observed yield increases in the region during recent decades has occurred as the result of wetter, less stressful growing season weather conditions. A better understanding of the effect of historical climate change improves our ability to predict how future climate change may effect crop production. This knowledge will help us better prepare for anticipated climate change.

Technical Abstract: Weather and climate have had major influences on crop production in the Upper Great Lakes states of Michigan, Minnesota, and Wisconsin during the past century. However, isolation of the impact of weather is difficult because of the confounding effects of technological improvements in agriculture, which have resulted in significant yield increases. This study was conducted to identify climatological impacts on the production o three crops commonly grown in the region without the influence of technology during the period of 1895 to 1996. DAFOSYM, CERES-Maize, and SOYGRO models were used to simulate crop growth, development, and yield of alfalfa, maize, and soybean crops, respectively, while holding all input variables, except weather, constant. Regionally, low precipitation and moisture stress were chief limitations to simulated crop yields. However, for maize and soybean in northern sections of the region, the primary climatological constraint was growing season length and the lack of sufficient thermal time (growing degree days) for optimum crop production. Simulated maize and soybean yields 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 decreased potential evapotranspiration. Consistent trends were not found for alfalfa. The simulated yields support previous research identifying a period of 'benign climate,' which favored crop production in the region from 1954-1973, that were both preceded and followed by periods of greater yield variability. The study suggests that at least part of the observed yield increases in the region during recent decades has occurred as the result of wetter, less stressful growing season weather conditions.