Nitrate-N from agricultural fields is a source of pollution to fresh and marine waters via subsurface tile drainage.  Sensor-based technologies that allow for in-season monitoring of crop nitrogen requirements may represent a way to reduce nitrate-N loadings to surface waters by allowing for fertilizer application on a more precise spatial and temporal resolution.  However, little research has been done to determine its effectiveness in reducing nitrate-N losses.  In this study, the field scale hydrologic and nitrogen simulation model Drainmod-NII was used to estimate nitrate-N loads for different fertilizer application rates and timings to corn for a field site in Waseca, Minnesota.  The results of the simulation, along with results from two other locations in southern Minnesota (Lamberton and Willmar) were used in a regression analysis to develop equations that predict nitrate-N load for the region as a function of climate and fertilizer timing and application rate in southern Minnesota.  Fertilizer timing treatments used in model simulation included fall, spring, and variable rate nitrogen (VRN) applications, where the VRN application involved half of the fertilizer applied before planting and the remaining half at approximately corn V6 growth stage.  Drainmod results showed the highest nitrate loads occurred for all fall application rates, followed by spring, with VRN having the lowest nitrate loads.  An exponential regression model which used fertilizer application rate and growing season precipitation as the dependent variables showed good agreement with Drainmod results, with R2 of 0.46, 0.49, 0.52 for spring, split-VRN, and fall application timing respectively.  The regression model showed that the variation in nitrate-N load between the timing treatments was highly related to annual precipitation and fertilizer application rates.  For a growing season precipitation of 60 cm, the “best-case” scenario of split-VRN, applied at a rate of 100 kg N/ha  results in 14 kg N/ha less nitrate lost than the “worst-case” scenario of fall application at a rate of 180 kg N/ha (a 58% reduction).  At 100 cm of precipitation, the “best-case” split-VRN, low rate application results in 67 kg N/ha less field nitrate losses compared to the “worst-case” fall, high rate application (59% reduction).