Simulated NH＋-N Deposition Inhibits CH4 Uptake and Promotes N2O Emission in the Meadow Steppe of Inner Mongolia, China

• Published in: 土壤圈：英文版 Vol. 27; no. 2; pp. 306 - 317
• Main Author: LIU Xingren ZHANG Qingwen LI Shenggong ZHANG Leiming REN Jianqiang
• Format: Journal Article
• Language: English
• Published: 2017
• Subjects: CH4吸收; CH4通量; N2O排放量; 内蒙古; 氮沉降; 草原土壤; 草甸草原; （NH4）2SO4
• ISSN: 1002-0160; 2210-5107

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 N20 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.