title: Modeling impacts of alternative practices on net global warming potential and greenhouse gas intensity from rice-wheat annual rotation in China.
abstract: BACKGROUND
  Evaluating the net exchange of greenhouse gas (GHG) emissions in conjunction with soil carbon sequestration may give a comprehensive insight on the role of agricultural production in global warming.
  
  
  METHODS
  Measured data of methane (CH(4)) and nitrous oxide (N(2)O) were utilized to test the applicability of the Denitrification and Decomposition (DNDC) model to a winter wheat - single rice rotation system in southern China. Six alternative scenarios were simulated against the baseline scenario to evaluate their long-term (45-year) impacts on net global warming potential (GWP) and greenhouse gas intensity (GHGI).
  
  
  RESULTS
  The simulated cumulative CH(4) emissions fell within the statistical deviation ranges of the field data, with the exception of N(2)O emissions during rice-growing season and both gases from the control treatment. Sensitivity tests showed that both CH(4) and N(2)O emissions were significantly affected by changes in both environmental factors and management practices. Compared with the baseline scenario, the long-term simulation had the following results: (1) high straw return and manure amendment scenarios greatly increased CH(4) emissions, while other scenarios had similar CH(4) emissions, (2) high inorganic N fertilizer increased N(2)O emissions while manure amendment and reduced inorganic N fertilizer scenarios decreased N(2)O emissions, (3) the mean annual soil organic carbon sequestration rates (SOCSR) under manure amendment, high straw return, and no-tillage scenarios averaged 0.20 t C ha(-1) yr(-1), being greater than other scenarios, and (4) the reduced inorganic N fertilizer scenario produced the least N loss from the system, while all the scenarios produced comparable grain yields.
  
  
  CONCLUSIONS
  In terms of net GWP and GHGI for the comprehensive assessment of climate change and crop production, reduced inorganic N fertilizer scenario followed by no-tillage scenario would be advocated for this specified cropping system.
authors.affiliation: Jiangsu Key Laboratory of Low Carbon Agriculture and GHGs Mitigation, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, China.
authors.forename: Jinyang
authors.initials: J
authors.lastname: Wang
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Zhang
authors.forename: Yinglie
authors.initials: Y
authors.lastname: Liu
authors.forename: Xiaojian
authors.initials: X
authors.lastname: Pan
authors.forename: Pingli
authors.initials: P
authors.lastname: Liu
authors.forename: Zhaozhi
authors.initials: Z
authors.lastname: Chen
authors.forename: Taiqing
authors.initials: T
authors.lastname: Huang
authors.forename: Zhengqin
authors.initials: Z
authors.lastname: Xiong
mesh_terms: D002681:China; D018556:Crops, Agricultural; D005740:Gases; D057232:Global Warming; D017752:Greenhouse Effect; D008962:Models, Theoretical; D012275:Oryza
chemical_list: D005740:Gases