Agriculture contributes 85% of the anthropogenic N2O emissions to the atmosphere.  Over half of these emissions come from soil.  Nitrogen enrichment of soil from legumes, manure, and fertilizer results in increased emissions.  Production of N2O varies by day and by year and is driven by soil water and plant growth.  While the process of N2O production and emission is difficult to regulate, N fertilizer technology and soil management offer opportunities to reduce N2O emissions on cropland soils.  Improved synchrony of soil N availability with plant N uptake often reduces N2O emissions.  Measurement of N2O emissions is critical for assessing N management strategies.  Measurement includes point sampling to large field assessment.  Due to the dynamic nature of N2O emissions, routine monitoring of N2O is difficult and expensive.  Therefore, modeling is critical to the understanding and up scaling of N2O emissions.  Modeling when verified is an essential tool for assessing N2O emissions in cropping systems.