Urease inhibitors (UIs)
In the EU 27+UK, Nitrogen (N) fertilisers such as straight-nitrates (AN+CAN), Urea and N-containing compounds represent approximately 75% of the annual fertilizer consumption.
Readily available Urea it is an attractive fertiliser for farmers due to its high N content, low cost and good water solubility. Nevertheless, ammonia volatilisation potential after field application represents a challenge to the use of urea.
Furthermore, ammonia can be transported over long distances causing eutrophication and acidification in non-agricultural areas, e.g. rain forests. This can be mitigated to a large extent via urease inhibitor usage, as urea treated with UIs can contribute to a 42.5% and 9% reduction of ammonia emissions and nitrous oxide emissions from mineral fertilisers, respectively.
 IFA data – average 2015-18 EU 27+UK and EMEP/EEA air pollution emission inventory guidebook 2019
Nitrification inhibitors (NIs)
On the other hand, NIs applied to urea and ammonium containing fertilisers like ammonium nitrate, calcium ammonium nitrate, ammonium sulphate and NPK compounds reduce nitrous oxide emissions and nitrate leaching.
Research shows using UI and NIs with urea and ammonium containing fertilisers can mitigate nitrous oxide emissions by 47%, leading to significant carbon abatement of crop production systems.
Taking into account the effect of saving nitrogen losses of about 619 kT nitrogen and average CO2eq emissions of 3.5 t per ton of fertilisers nitrogen produced in Europe the overall potential impact of inhibitor technology on emissions from nitrogen fertilisers sums up to about 32 million tons of CO2 equivalents or about 33% reduction of the carbon footprint of current nitrogen fertiliser use. This is equivalent to removing 8.9 Million cars from the street!
Nitrification inhibitors can reduce N2O emissions by 38% as well as nitrates leaching by 18%.
|Pathways of nitrogen losses||Urease inhibitor impact (UI)||Nitrification inhibitor impact (NI)||UI+NI|
|Fertilizer||Annual Consumption*||Ammonia emisison factor**||Ammonia||Nitrous oxide||Nitrate ||Ammonia emission||Nitrous oxide emission||Nitrogen consumption||Nitrous oxide emission||Nitrate leaching||Nitrogen consumption||Nitrogen consumption|
|kt nitrogen||% N||kt NH3-N||kT N2O-N||kt N||kt NH3-N||kt N2O-N||kt N||kt N2O-N||kT NO3-N||kt N||kt N|
|Calcium ammonium nitrate||2557||1.1||28.127||25.57||306.84||9.7166||55.2312||64.9478||64.9478|
|Nitrogen solutions (UAN)||1534||8.7||133.458||15.34||184.08||53.3832||3.835||57.2182||5.8292||33.1344||38.9636||96.1818|
|other straight nitrogen||600||1.2||7.2||6||72||2.28||12.96||15.24||15.24|
|CO2 equivalents (kt)||54182.8666||4823.6366||1519.44646472||20589.489308||1170.34991856||28102.92229128|
** EMEP/EEA air pollutant emission inventory guidebook 2019 – technical guidance to prepare national emission inventories