Sulfur deposition suppressed nitrogen-induced soil N2O emission from a subtropical forestland in southeastern China

Subtropical forestland soils are important sources of nitrous oxide (N2O); however few studies haveevaluated the effects of sulfate (S) deposition and its interaction with nitrogen (N) on soil N2O emis-sions from subtropical forestland. A field experiment was conducted in subtropical forestland in Yingtan,Jiangxi Province, China, between June 2011 and May 2013, to measure soil N2O fluxes under three N(NO3−) application levels (0, 40, and 80 kg N ha−1yr−1), two S (SO42−) levels (0 and 45 kg S ha−1yr−1), andtheir combinations. The soil N2O flux was significantly (P < 0.05) correlated with only soil temperaturein all treatments over the study period; however, soil moisture, and NH4+and NO3−contents were alsoincluded in the stepwise multiple linear regression equations during the N and/or S application period(March to September). N2O emissions under natural conditions in the subtropical forestland were esti-mated at 0.42 kg N2O-N ha−1yr−1, and were significantly (P < 0.05) increased by 97–330% under the Napplication. In contrast, soil N2O emissions decreased to 0.36 kg N2O-N ha−1yr−1in the S-applied soil andwere significantly (P < 0.05) reduced by 27–36% in the S plus N-amended soils. Our results indicated thatatmospheric N deposition potentially increases soil N2O emissions in subtropical forestland, whereas Saddition has the potential to mitigate N2O emissions. Given that increased N deposition is expected inthe future, S deposition in subtropical forestland soils could suppress N2O emissions to some extent.