Nitrogen deposition was experimentally increased on a Scottish peat bog over a period of 13 years (2002–2015), simulating pollution from agricultural and fossil-fuel sources. We measured emissions of the greenhouse gas, nitrous oxide (N₂O), in response to the increased nitrogen input. In the plots treated with ammonium and nitrate solution, no response was seen. Areas subjected to high ammonia emitted more N₂O than expected. Differences were related to impacts on the vegetation.