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Simulated NH4+-N Deposition Inhibits CH4 Uptake and Promotes N2O Emission in the Meadow Steppe of Inner Mongolia, China
- LIU, Xingren, ZHANG, Qingwen, LI, Shenggong, ZHANG, Leiming, REN, Jianqiang
- Pedosphere 2017 v.27 no.2 pp. 306-317
- ammonium nitrogen, ammonium sulfate, chromatography, cold, diurnal variation, field experimentation, greenhouse gas emissions, growing season, meadows, methane, methane production, nitrogen, nitrous oxide, soil temperature, soil water, steppes, China
- Few studies are conducted to quantify the effects of enhanced N deposition on soil nitrous oxide (N2O) emission and methane (CH4) uptake in the meadow steppe of Inner Mongolia, China. A two-year field experiment was conducted to assess the effects of nitrogen (N) deposition rates (0, 10, and 20 kg N ha−1 year−1 as (NH4)2SO4) on soil N2O and CH4 fluxes. The seasonal and diurnal variations of soil N2O and CH4 fluxes were determined using the static chamber-gas chromatography method during the two growing seasons of 2008 and 2009. Soil temperature, moisture and mineral N (NH4+-N and NO3−-N) concentration were simultaneously measured. Results showed that low level of (NH4)2SO4 (10 kg N ha−1 year−1) did not significantly affect soil CH4 and N2O fluxes and other variables. High level of (NH4)2SO4 (20 kg N ha−1 year−1) significantly increased soil NO3−-N concentration by 24.1% to 35.6%, decreased soil CH4 uptake by an average of 20.1%, and significantly promoted soil N2O emission by an average of 98.2%. Soil N2O emission responded more strongly to the added N compared to CH4 uptake. However, soil CH4 fluxes were mainly driven by soil moisture, followed by soil NO3−-N concentration. Soil N2O fluxes were mainly driven by soil temperature, followed by soil moisture. Soil inorganic N availability was a key integrator of soil CH4 uptake and N2O emission. These results suggest that the changes of availability of inorganic N induced by the increased N deposition in soil may affect the CH4 and N2O fluxes in the cold semi-arid meadow steppe over the short term.