Strategies to mitigate nitrous oxide (N₂O) emissions can be achieved with the use of simulation models and Geographic Information Systems (GIS). The LEACHMN model was calibrated using field data on N₂O emissions, and soil physical, and chemical properties collected from a short-term simulated rainfall experiment in late June 2004. The experimental plots were on clay loam and loamy sand soils in Northern New York, each site with two cropping histories (maize after grass vs. continuous maize), and a factorial of tillage (no-till vs. plow-till) and N application (full fertilization at planting, 134 kg N ha^-1 vs. starter-only fertilization, 20 kg N ha^-1) on maize (Zea mays L.). Calibration involved adjusting rate constants to optimize the fit between predicted and measured data. Strong effects of cropping history, tillage, and N application on the rate constants were observed with no-till and full fertilization showing high N₂O losses. N₂O losses averaged four times higher on the clay loam compared to the loamy sand. Under no-till, full season fertilizer application at planting resulted in 4.7 and 2.3 kg N ha^-1 greater cumulative N₂O losses than starter-only fertilizer application on maize after grass and continuous maize plots, respectively. Smaller N₂O emissions were observed on plots under plow-till treatments compared to no-till. Under plow-till, full fertilization at planting resulted in 0.95 and 0.81 kg N ha^-1 greater cumulative N₂O losses than starter-only fertilization on maize after grass and continuous maize plots, respectively. From this, it can be concluded that N₂O losses are higher with no-till vs. plow-till, full fertilization, and when maize is rotated after grass. Timing and rate of N fertilizer applications are particularly important in no-till systems to minimize N₂O losses. Otherwise, the potential greenhouse gas benefit of C sequestration in no-till systems may be partly or completely offset by increased emissions of N₂O, a greenhouse gas that is approximately 310 times more potent than CO₂. The LEACHMN model was combined with environmental databases to map potential N₂O losses at the regional scale based on different management scenarios for greenhouse gas reduction. The results of upscaling from field to statewide scale using soil maps and GIS under various management scenarios identified that N management is critical in reducing environmental and economical losses, and mitigation measures to reduce these losses can be formulated from a field to statewide basis. Keywords: GIS, leaching models, model calibration, N dynamics, N₂O emissions, timing of N application