Ecophysiology of Corn Yield Potential and N Requirements Under Variable Water Management

Water availability is the main limiting factor and cause of yield gap between potential and average corn grain yields in Kentucky and many agricultural areas of the US. The increased interest and acreage in irrigation could help remove water limitations and increase corn yield. Irrigation allows us to investigate corn yield potential under no water deficiencies, something that has not been studied in great detail in this region of the US. In addition, N fertilizer requirements under conditions of high yield potential and no water limitations have not been quantified. Quantification of yield potential, water requirements and N fertilizer requirements and their trade?offs on final net economic returns is essential for producer's decisions and for the sustainable development of these agricultural areas. Nitrogen requirements will be greatly dependent on the irrigation efficiency of a given system, soil type, environmental conditions, and the associated grain yield potential for a given location and year. As a result, management of N fertilizer is not a simple task for producers under this wide range of conditions and water availability. However, failure to optimize N use can have critical implications on final net economic returns. Excessive N fertilizer inputs combined with a low irrigation efficiency can lead to large loads of inorganic N lost through drainage and has been associated with contamination of ground water and stream water flows.