Effects of Short-Term Weather Events on Corn Yield

The study of short-term weather events on crop yield is complicated by the difficulty and cost of collecting enough plant samples, frequently enough to compare the growth differences during different weather conditions. The traditional approach to this type of study was to attempt to apply a stress during a specific crop growth stage and subject all crop treatments to the same weather conditions for the rest of the growing season. A problem with this approach is that the measure of the impact is the final yield. A growing season is often typified with periods of optimal growing conditions along with periods of sub-optimal growing conditions. Continuous monitoring of carbon dioxide fluxes from a crop canopy, provides a method to observe the rate of photosynthesis and crop growth without destroying the crop. As part of the National Oceanic and Atmospheric Administration's (NOAA) contribution to the Global Energy and Water Cycle Experiment (GEWEX) a long term energy/carbon flux tower system was established on a no-till corn and soybean field in central Illinois. Flux measurements have been collected continuously since August of 1996. Corn was grown in the field in both 1997 and 1999. The yield in 1997 was 8,991 kg ha-1 and 11,569 kg ha-1 in 1999. This paper describes the weather conditions throughout the growing season and the weather conditions that resulted in the lower yield in 1997.