title: Effects of elevated atmospheric CO2 concentration and temperature on the soil profile methane distribution and diffusion in rice-wheat rotation system.
abstract: The aim of this experiment was to determine the impacts of climate change on soil profile concentrations and diffusion effluxes of methane in a rice-wheat annual rotation ecosystem in Southeastern China. We initiated a field experiment with four treatments: ambient conditions (CKs), CO2 concentration elevated to ~500 μmol/mol (FACE), temperature elevated by ca. 2°C (T) and combined elevation of CO2 concentration and temperature (FACE+T). A multilevel sampling probe was designed to collect the soil gas at four different depths, namely, 7 cm, 15 cm, 30 cm and 50 cm. Methane concentrations were higher during the rice season and decreased with depth, while lower during the wheat season and increased with depth. Compared to CK, mean methane concentration was increased by 42%, 57% and 71% under the FACE, FACE+T and T treatments, respectively, at the 7 cm depth during the rice season (p<0.05). Mean methane diffusion effluxes to the 7 cm depth were positive in the rice season and negative in the wheat season, resulting in the paddy field being a source and weak sink, respectively. Moreover, mean methane diffusion effluxes in the rice season were 0.94, 1.19 and 1.42 mg C/(m2·hr) in the FACE, FACE+T and T treatments, respectively, being clearly higher than that in the CK. The results indicated that elevated atmospheric CO2 concentration and temperature could significantly increase soil profile methane concentrations and their effluxes from a rice-wheat field annual rotation ecosystem (p<0.05).
authors.affiliation: Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yang
authors.affiliation: Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Zhaozhi
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Man
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Heng
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Xuhui
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Genxing
authors.initials: G
authors.lastname: Pan
authors.affiliation: Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Jianwen
authors.initials: J
authors.lastname: Zou
authors.affiliation: Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, China. Electronic address: zqxiong@njau.edu.cn.
authors.forename: Zhengqin
authors.initials: Z
authors.lastname: Xiong
mesh_terms: D000383:Agriculture; D000388:Air / Q000032:analysis*; D002245:Carbon Dioxide / Q000032:analysis*; D002681:China; D057231:Climate Change; D004784:Environmental Monitoring / Q000379:methods; D008697:Methane / Q000032:analysis*; D012275:Oryza / Q000254:growth & development*; D012987:Soil / Q000737:chemistry* / Q000592:standards; D013696:Temperature; D014908:Triticum / Q000254:growth & development*
chemical_list: D012987:Soil; D002245:Carbon Dioxide; D008697:Methane
keywords: CH(4) concentration; Climate change; Diffusion efflux; Paddy field; Soil profile; T-FACE