A smaller literature study and a data retrieval on N₂O emissions, N mineralization and C:N ratios from projects recently conducted at SLU and from other Swedish sites have been performed to evaluate whether the current IPCC Tier 1 approach with a default emission factor of 1% (EF1) for N₂O emissions from agricultural soils and other land use categories should be changed to a higher Tier with more specific EFs.

The study showed that the use of a default N₂O EF of 1% of the N applied to soils would either under- or overestimate N₂O emissions. It was also concluded that there is no relationship between total N input and N₂O emissions, i.e. high fertilizer input must not be related to high N₂O emissions and low fertilizer input can result in high N₂O emissions. Even though N₂O emissions from different Swedish land use categories were lower as the default EF1 in 8 of the 21 reported data sets, there is clear evidence to change from the IPCC Tier 1 approach for N2O emissions to more adjusted EFs related to a country-specific methodology. The strong relationship between C:N ratios and N₂O emissions from drained forested histosols may be used to improve our ability to predict N₂O emissions from other land use categories such as grassland and cropland.