• Whether all nitrogen input sources have been estimated, in a consistent mode to the nitrogen sources considered in direct emissions;
• Whether default or country-specific activity data, emission factors, and partition fractions have been used for the following categories of nitrogen: synthetic fertilizers applied to soils, animal manure, and sewage sludge discharged to rivers, in particular if they represent a significant portion of total emissions (and indirect N₂O emissions from agricultural soils is a key category);
• Whether it has been demonstrated that any default factors used are applicable to the national circumstances.

Reference:
IPCC Good Practice Guidance, Section 4.8