It is not known whether tailoring nitrogen (N) needs to the variable growth of heterogeneous plant stands results in increased yields.  One of the prerequisites for a successful management system is to determine at which scale to operate when applying sidedress N fertilizer in corn. This study was conducted to determine the N application resolution at which N competition influences corn grain yields, and to determine where corn grain yields are maximized. This experiment was established in 2005 at two sites (Efaw and Lake Carl Blackwell - LCB) in Stillwater, OK with 14 treatments arranged in a completely randomized design (CRD) with three replications. Treatments included five distribution scenarios of sidedress N fertilizer application, fixed N rate of 45 kg N ha^-1 applied preplant, and a check plot, at 18 and 30 cm plant spacings. In 2005, well-established corn at LCB, due to sufficient moisture, had a higher grain yield than at Efaw, 15.2 vs. 4.8 Mg ha^-1. In 2006 however, corn at Efaw obtained a grain yield of 7.6 Mg ha^-1 while LCB had only 5.3 Mg ha^-1. Corn at Efaw had a greater response to the N distribution scenarios in both 2005 and 2006. At the planting distance of 30 cm, applying sidedress N every three plants resulted in the highest grain yields of 5.4 Mg ha^-1 at Efaw and 18.8 Mg ha^-1 at LCB. At a planting distance of 18 cm, distributing N fertilizer over the entire row recorded the highest grain yields across treatments at Efaw for 2005 (7.2 Mg ha^-1) and 2006 (9.8 Mg ha^-1), and at LCB in 2006 (8.2 Mg ha^-1). These results demonstrate that the optimum resolution for sidedress N fertilizer application changes depending on the extent of variation of the plant stand as influenced by plant density, and the combined effect of temporal and field spatial variability. To account for field variability, it is therefore essential to modify N application schemes based on optimum resolution identified in-season.