Short-term response of soil N-cycling genes and transcripts to fertilization with nitrification and urease inhibitors, and relationship with field-scale N2O emissions

Our study aimed to describe short-term changes in N-cycling genes and transcripts and nitrous oxide (N2O) emissions after fertilization with urea-ammonium nitrate (UAN) with or without the addition of nitrification+urease inhibitors (NUI). Adding NUI did not prevent an N2O flux event but reduced its duration and magnitude by more than 50%, and net cumulative N2O emissions for the sampling period by ~68%. NUI effects on N-cycling microorganisms were evident 9 days after fertilizer was applied, as a transient reduction (40–56%) of ammonia-oxidizers and denitrifiers. Unexpectedly, N2O emissions were negatively associated with the ratio between nitrite-reducers and N2O-reducers. NUI effects on N-cycling microorganisms were minor and transient but resulted in a field-scale reduction in N2O emissions, possibly due to a combination of environmental factors and legacy effects from previous years of treatment.