Effects of nitrogen and phosphorus additions on nitrous oxide fluxes in a peatland in NE China.

Aims: The release of the major greenhouse gas N₂O from peatlands may be affected by current global change. We tried to answer how N₂O emission from peatlands responds to phosphorus (P) addition and the co-addition of P and nitrogen (N). Methods: We investigated the long-term (12 years) effects of N (50 and 100 kg ha⁻¹ yr⁻¹) and P (5 kg ha⁻¹ yr⁻¹) additions and their interaction on N₂O fluxes in Hani peatland during the 2019 growing season. Results: The addition of P, a low level of N or their co-addition had no effect on the source/sink function of N₂O in the peatland. However, a high level of N addition turned the peatland into a sink of N₂O with a cumulative flux of −164 ± 51 g m⁻² during the growing season. This was probably due to the acceleration of plant litter decomposition, stimulation of hydrolase activity, and changes in the stoichiometric ratio of the peat soil. The co-addition of P and a high level of N turned the peatland into a source of N₂O with a cumulative flux of 144 ± 54 g m⁻² during the growing season by relieving nutrient limitation, accelerating the growth of vascular plants, and altering the litter input. Conclusions: We suggest that the increase in nutrient availability caused by N deposition and agriculture fertilization can alter the N₂O source/sink function of peatlands. These changes may have significant implications for the overall balance of greenhouse gas emissions and the role of peatlands in mitigating climate change. [ABSTRACT FROM AUTHOR]