Today more than ever, with the increasing population of the world in each year, food production is an urgent task which has received increasing attention. Increased food production depends on judicious use of resources. Many soil, climatic, plant, and management factors affect the way a crop will respond to irrigation, fertilizer, and other management practices. Among these uncertainties and factors, climate is a dominant factor. Accurate prediction the impacts of climate on crop yield has major economic and environmental implications. However, few studies have been done on the Midwest crop field.
Computer simulation models of the soil-crop-atmosphere system can make a valuable contribution to both furthering our understanding of the processes determining crop responses and predicting crop performance. In this study, a crop growth and development (CROPGRO-Soybean) model has been adopted to predict the impacts of the climate on the yield distributions in a soybean field in northern Iowa. The field is divided into 30 plots 0.41 ha in size. Data consisting of soil water content at several depths, as well as soybean yield of each plot have been collected during the past 5 seasons (1993-1997). The performance of the model was determined based on the predictions of temporal and spatial soil water content, and tile flow. The results of model show that there are very good agreements between the predicted and measured soybean yields. Crop yields are strongly dependent on the climate conditions during the growing season in the Midwest.