A challenge for hard red spring wheat (HRSW) (Triticum aestivum L. emend Thell.) producers is to obtain both high yields and market-required grain protein content (GPC). The ability to accurately predict HRSW yield with the Decision Support System for Agrotechnology Transfer (DSSAT) crop model early in the growing season may help producers determine probable GPC and lead to management decisions on whether to apply supplemental nitrogen (N) to enhance protein. A management decision HRSW producers may consider in high yielding environments is a late-season foliar N application to increase GPC. A second objective of this research was to test methods to improve the efficiency of a foliar N application. Improving the efficiency of a late-season foliar N application coupled with the ability to predict high yielding environments using DSSAT, can provide producers with effective management tools to determine the optimum situation in which supplementing GPC will have the most economic success.