To evaluate the accuracy of the current emission factor (EF) for conventional urea in Germany, ammonia (NH₃) emissions were measured using the integrated horizontal flux (IHF) method with ALPHA passive samplers following urea applications in 2021–2023. Measurements were conducted across six agroecological regions under winter wheat cropping, with nitrogen application rates of 145–230 kg N ha⁻¹, resulting in 51 campaigns.
Emission rates (NH₃Ninput) ranged from 1.1% to 20.7% (median 4.8%, mean 8.5%), significantly lower than the 2019 IPCC (14.2%) and 2023 EMEP (16.1% for pH < 7) estimates. NH₃Ninput was influenced by soil texture and rainfall but not nitrogen application rates, with higher emissions observed on sandy soils.
These findings suggest current EFs overestimate NH₃ emissions from urea applied to winter wheat in Germany. While emissions may vary due to inter-annual and environmental factors, a national EF for Germany could improve NH₃ emission estimates and the evaluation of mitigation strategies.