Region-specific emission factors for Brazil increase the estimate of nitrous oxide emissions from nitrogen fertiliser application by 21%

The use of synthetic nitrogen fertilisers is one of the most important land management practices proposed to improve crop and pasture productivity. The use of such fertilisers in excess can lead to greenhouse gas (GHG) emissions, linked to climate change, as well as ammonia emissions, linked to eutrophication and soil acidification. This context is especially important in Brazil, which is responsible for a significant share of the food produced in the world.

To assess the impact of the use of nitrogen fertilisers, Andre M. Mazzetto and colleagues conducted a structured review of Brazilian studies on the emission of nitrous oxide and ammonia volatilisation suggested by the IPCC for nitrous oxide and ammonia (1 and 11%, respectively) are lower than the mean values they found in their review (1.12 and 19%, respectively).

The results of this study led by Mazzetto showed that non-urea fertilisers (ammonium nitrate or ammonium sulphate) had a lower emission factor (EF) for nitrous oxide (1.07 and 0.60%, respectively) and ammonia (3.17 and 14%, respectively) in comparison with urea. The use of nitrification and urease inhibitors resulted in a reduction of the EFs of nitrous oxide (74% lower) and ammonia (43% lower) when compared with the Urea EF.

Urea is the most common fertiliser used in Brazil, and the change for non-urea fertilisers or the use of inhibitors could lead to a reduction of 23% in the total nitrous oxide inventory. The use of the new region-specific EFs results in an increase of 21% in the final nitrous oxide emission inventory.