Warming Nighttime Temperatures and Crop Health in the Corn Belt

Over the last century nighttime minimum temperatures have been increasing at a faster rate than daily maximum temperatures. This warming trend has caught the attention of climatologists and agricultural scientists as they attempt to address the potential effects of elevated nighttime minimum temperatures on the health of these crops, which are so important to the U.S. economy. In this study, ten sites represent the Corn Belt of the United States. Those sites are spread across an area in which the average minimum nighttime temperatures for each of the three primary growing months of the year (June, July, August) increased from 1950-2011. Since this is a relatively new phenomenon, the effects of increased nighttime temperatures are not well understood. The main variables that can affect the growth of crops under elevated nighttime temperatures are: a shift in agro climatic zones resulting in an introduction of new pests formerly foreign to the crops, deviation from prime respiration temperatures and lastly the subsequent change in the properties of air associated with warmer air that would likely exist in a changing climate. Warmer nighttime temperatures raise the respiration rate of corn plants to levels above the optimum rate. This leads to " wasteful respiration, " which often compromises the plant structure (leading to " stalk cannibalization "), negatively affects the overall health of the plant, and jeopardizes maximum production. Most crop simulation models and experimental results used in climate and agriculture studies were not designed well enough to quantify multiple stress effects associated with this research. The complexity and input requirements of a reliable agro ecosystem model are such that the predictive capacity of the simulation models represents a much smaller area than desired, decreasing the validity of a large-scale application. More research needs to be conducted comparing differing agro environments (since each environment contains a different set of target variables like soil type, rainfall, plant species, and climate events). Such research is necessary to help untangle climate effects from other factors affecting maximum crop yield.