Annual consumption and types of synthetic nitrogen fertilizers: Ammonia emission indicators for mitigation strategies in the European Union

Anthropogenic ammonia (NH₃) emissions are primarily derived from agricultural activities. NH₃ emissions from synthetic nitrogen (N) fertilizers are associated with the annual consumption of various N fertilizers. In this study, the annual consumption of different types of synthetic N fertilizers in the EU countries, derived from the database of the International Fertilizer Association, was analyzed, and the implementation of mitigation measures for NH₃ emissions at the national level was assessed. NH₃ emissions were estimated using the emission factors of different N fertilizers in cool, temperate and hot climates, and low- and high-pH soils, as the European Environment Agency proposed. The results revealed that the annual consumption of various synthetic N fertilizers (average values from 2016 to 2020) varied markedly in different EU countries. France, Germany, Poland, Spain, and the United Kingdom had the largest annual consumption of synthetic N fertilizers. NH₃ emissions from urea-based fertilizers are the highest in most EU countries. The annual NH₃ emissions were associated with the type of synthetic N fertilizer consumed. For example, although the annual synthetic N fertilizer consumption in Germany was 38% and 41.5% higher than those in Spain and Italy, the annual NH₃ emissions in Germany were 63% and 20% lower than those in Spain and Italy, respectively, due to the high proportion of urea-based fertilizers with the highest emission factor among the synthetic N fertilizers in Spain and Italy. Thus, mitigation strategies should be tailored to specific types of N fertilizers with high emission factors and proportions to minimize NH₃ emissions. Since the NH₃ emissions from urea-based fertilizers are the highest in the EU countries, especially in the top five countries, we recommend the addition of urease inhibitors to urea fertilizers as one important strategy for mitigating NH₃ emissions.