The IPCC (Intergovernmental Panel on Climate Change) calculation model for nitrous oxide (N2O) emissions from agricultural land includes emissions from the nitrogen turnover in crop residues. The nitrogen content of crop residues is calculated using primary crop statistics in combination with recalculation factors, that is, the ratios of crop residue/primary crop and the nitrogen content in crop residues. In addition, information on removed crop residues is used to subtract that part of the crop residues that is not turned over on agricultural land.

A comparison between data used in different countries reveals great differences.1 Variations in climate, soil fertility and production methods across different countries partly explain some of the differences. Nevertheless, it is likely that these differences also depend on different definitions as well as on variations in the trial data. A more systematic comparison of the recalculations for different countries requires well-documented sources of information