Research is needed to understand complex interrelationships among crop, soil, climate, and management and to predict economic and environmental impacts of alternative production systems. Crop models serve as a framework for transdisciplinary research teams to address how to better meet societal needs for food production, economic viability, and the environment. These models are increasingly used by action agencies, such as Extension services and agricultural and environmental agencies, to evaluate likely outcomes of different recommendations and policies to achieve societal goals and by the private sector (e.g., by plant breeding companies, crop input suppliers, production enterprises, banks, and multinational food suppliers). Crop model integrate information across a wide range of disciplines to address complex problems, incorporating information from molecular to global scales. Examples are discussed in which advances are being made in incorporating molecular genetics information for evaluating the performance of genotypes in different production systems and in integrating crop models with General Circulation Models that simulate climate change at the global scale. Also excellent examples where crop models have been used to evaluate best management practices at a field scale, for precision agriculture, watersheds, and regional forecasts will be discussed.

During the last two decades, there have been limited advances in crop model capabilities. One reason is that advances require good data for a wide range of soils, weather, and management situations. Data for model development and evaluation have typically been limited to a few experiments by small model development teams. In contrast, many experiments are conducted annually for all major food crops, but these data are not used as effectively as possible for improving crop models. National or global efforts are needed to remedy this situation. Two other rather major needs exist. Education programs are needed to provide the necessary concepts and skill sets to the next generation of model developers and users, particularly at the university graduate level and for post graduate professionals. Another need is to create a community of science with crop modeling groups cooperating worldwide so that the models provide the best capabilities that our agricultural sciences can provide. This is beginning to occur in several new exciting research programs that will be discussed.