New paper: Urea application

The use of urea fertilizers in agriculture is associated with many negative environmental impacts and is a source of ammonia (NH₃) and nitrous oxide (N₂O) emissions. Such losses from urea fertilizer can be avoided by various mitigation measures such as inhibitors and incorporation. In a laboratory study, three different mitigation principles, urease inhibitor (UI) alone and in combination with nitrification inhibitor (NI) and closed slit incorporation of urea fertilizer, were investigated on a sandy loam soil. In addition to NH₃ and N₂O emissions, N₂O isotopocules were analyzed by isotope ratio mass spectrometry, which confirmed the high contribution of nitrification to N₂O production. Slit incorporation showed the greatest effect on reducing NH₃ emissions by 79.6 % (40.6 % for UI and 46.7 % for UINI) compared to surface-applied urea. The N₂O reduction potential of UINI decreased significantly over the trial period. The initial increase in N₂O emissions due to incorporation did not lead to "polution swapping" in relation to the cumulative total emissions. Conclusion of our study: All selected measures show a high NH₃ emission reduction potential. Due to the varying effects on N₂O emissions over time, further studies should consider factors such as plant N uptake and precipitation with regard to "pollution swapping". In addition, effects of NI on non-target microbial communities should be considered to clarify potential environmental consequences and the long-term efficacy of inhibitor compounds.

https://doi.org/10.1016/j.agee.2024.109307