N2O emission from fertilizer use

The current IPCC guidelines for calculating national nitrous oxide (N2O) emissions from the use of N fertilizers has N input as the only controlling variable. This approach has the benefit of administrative simplicity but it also gives the impression that the only way to reduce N2O emission is to reduce N input. Our analysis of data available from the literature indicates a lower N induced emission factor compared to the current default value. However, N input explains less than 15% of the variability of the emission, hence, there are other drivers involved. A more realistic model that includes the main drivers should thus be developed and validated. Such models should also be useful tools for identification of fanning practices that may reduce N2O emission. Lack of information on many drivers as well as the unbalanced feature of the literature data available today complicate their use for this purpose. More long-term field trials (more than one year) are thus recommended. These should preferably be coordinated to reduce the amount of variables involved.