Fermentation pattern of methanogenic degradation of rice straw in anoxic paddy soil

摘要: The anaerobic degradation of different fractions rice straw in anoxic paddy soil was investigated. Rice divided up into stem, leaf sheath and blade. were mixed with incubated under conditions. Fermentation components started immediately resulted transient accumulation acetate, propionate, butyrate, isobutyrate, valerate, isovalerate caproate much higher concentrations the presence than absence straw. Also some unidentified compounds UV absorption could be detected. maximum these when using fractions, suggesting differences pathway during early phase incubation, i.e. Fe(III) sulfate serving as oxidants. When intermediates decreased to background values, CH4 production started. Rates incubations from stem>leaf blade>leaf sheath>unamended soil. During methanogenic phase, percentage contribution fermentation products determined by inhibition 2-bromoethanesulfonate (BES). Acetate (48–83%) propionate (18–28%) found main carbon flow CH4, irrespective fraction or its absence. Mass balance calculations showed that 84–89% formed via acetate various incubations. Radiotracer experiments 11–27% H2/CO2, thus confirming contributed 73–89% methanogenesis. Our results show addition affected pattern only degradation, but had no effect on later phase.