Relationship between nitrapyrin and varying nitrogen application rates with nitrous oxide emissions and nitrogen use...

Reducing nitrogen losses can be accomplished by mixing fertilizers with nitrification inhibitors (NI). In some agricultural systems, increasing soil N supply capacity by the use of NI could lead to improved N use efficiency (NUE) and increased crop yields. This study examined the effect of different N rates and NI in maize in the north of Iran. The maize was fertilized with urea at three levels (69, 115 and 161 kg N.ha^-1) alone or with nitrapyrin as NI. Increasing the N application rate resulted in a considerable rise in growing-season N₂O emissions. When nitrapyrin was used, N₂O emissions were dramatically reduced. NI treatment reduced N₂O emissions in the growth season by 88%, 88%, and 69% in 69, 115, and 161 kg of N.ha^-1, respectively. NI treatment reduced yield-scaled N₂O emissions; the lowest quantity of yield-scaled N₂O was found in 69 N + NI (0.09 g N₂O-N kg^-1 N uptake). Additionally, grain yield increased by 19%, 31% and 18.4% after applying NI to 69 N, 115 N, and N69, N115 and N161. Results showed that 115 N + NI and N69 treatments showed the highest (65%) and lowest (29%) NUEs, respectively. Finally, our findings show that NI can reduce N₂O emissions while increasing NUE and yield, but that the application method and rate of nitrapyrin application need to be improved in order to maximize its mitigation potential.