Nitrogen fertilizer use has been shown to increase emissions of nitrous oxide, a gas implicated in climate change and stratospheric ozone depletion. However, continued nitrogen inputs are also essential for supporting foreseeable demand for agricultural crops. Management practices that reduce emissions while supporting increased yields need to be specified in protocols to qualify as offsets in carbon trading schemes, and as ecological goods and services. We used several approaches, including meta-analysis, to draw conclusions from the largest possible dataset from Eastern Canadian studies in which nitrous oxide emissions were measured in response to application of nitrogen fertilizer. The objective was to identify specific effects of source, rate, timing and placement on nitrous oxide emissions per unit land area and per unit of crop yield. The findings are to be incorporated into the recently-approved Nitrous Oxide Emission Reduction Protocol, to meet the required standards for scientific backing of coefficients and methodology used in existing and anticipated regulatory mechanisms facilitating the trading of carbon credits.