Stable carbon isotope fractionation, carbon flux partitioning and priming effects in anoxic soils during methanogenic degradation of straw and soil organic matter
- 作者：Ralf Conrada ; conrad@mpi-marburg.mpg.de ; Melanie Klosea ; Quan Yuana ; Yahai Lub ; Amnat Chidthaisongc ; d
- 关键词：Methane production ; Rice straw ; Maize straw ; Soil organic matter ; Rice field soil ; Flux partitioning ; Priming effect
- 刊名：Soil Biology & Biochemistry
- 出版年：2012
- 期刊代码：96_00380717
- 类别：abs
- 出版时间：June, 2012
- 卷：49
- 期：Complete
- 页码：193-199
- 文件大小：409 K
摘要
Straw amendment is a common practice for improving the fertility of rice field soils, but it also enhances production of the greenhouse gas methane. To quantify carbon flux partitioning and priming effects due to straw amendment, we measured 未13C in CH4 and CH4 precursors produced in anoxic slurries of soil from Italy, China and Thailand after addition of straw from either rice (C3 plant) or maize plants (C4 plant), which have different 未13C signatures. The 未13C values of the CH4, acetate and CO2 produced were similar when expressed as the difference to the 未13C value of the straw applied. These results indicated that the 13C-isotopic fractionation involved in methanogenic decomposition was similar for rice straw and maize straw. However, measurement of CH4 produced in soil without or with straw showed that isotopic fractionation during methanogenic degradation of straw was smaller than during degradation of soil organic matter. Isotopic fractionation during hydrogenotrophic methanogenesis, measured in the presence of methyl fluoride, with straw was also smaller than with soil organic matter. The results show that 13C-isotopic analysis after application of rice straw and maize straw is a convenient approach for quantifying carbon flux partitioning during methanogenic degradation of straw and soil organic matter. In our experiments, straw degradation accounted for most of the CH4 production and caused a negative priming effect on the methanogenic degradation of soil organic matter.