微生物对暗棕壤添加玉米秸秆腐殖化进程的影响

Effects of different microorganisms on humification of corn stover incorporated in dark brown soil

针对微生物如何在土壤外源添加有机质的腐殖化进程中发挥作用这一科学问题,采用定量分析、元素组成、差热分析和红外光谱法,研究微生物对暗棕壤添加玉米秸秆腐殖化进程的影响并揭示不同微生物处理间的差异。结果表明,微生物处理能够显著促进有机物料的腐殖化,细菌由于对有机物料和腐植酸的利用度不高而产生的影响最小,真菌和放线菌的影响显著。腐植酸结构分析及PQ值(表征腐殖化程度)结果进一步揭示,微生物处理有利于HA(胡敏酸)的合成,并且FA(富里酸)有向HA转化的可能;细菌、真菌分别对腐植酸的N、H元素含量影响大,放线菌对腐植酸结构的影响主要表现在C=O键上;在培养后期,放线菌由于对纤维素类物质的充分利用而对腐植酸结构的影响超过了其他类群微生物。定量与定性分析结果能够相互印证,肯定了不同微生物对腐殖化进程的影响表现在不同培养阶段对不同物质和官能团的利用上。

Humification of organic materials in soil is greatly controlled by soil microbes.Different soil microbial communities may have different roles in this process.Here the effects of different microbial communities on the humification of corn stover incorporated in dark brown soil were studied by quantitative analysis,element composition analysis,differential thermal analysis,and Fourier transform infrared spectroscopy.Results showed that microorganisms could obviously promote the humification of the amended organic material.Fungi and actinomycetes had remarkable effects on relative content of humic acids,and were main drivers of the humification process.However,bacteria played small role in the humification process.The structure analysis of humic acids and the change of PQ values（an indicator of humification degree）further revealed the promotion of HA synthesis by microbial treatments and the possibility of FA conversion to HA.Actinomycetes affected the structure of humic acids mainly via C=O bond,while bacteria and fungi respectively impacted the N and H contents of humic acids.The influence of actinomycetes on humification process was more significant at the late stage of incubation than that of other microbes for actinomycetes could make full use of fiber materials.In the actinomycete treatment,the aliphatic characteristic of FA was the most obvious and the aromaticity of HA was the highest.Fungi played a pioneering role at the early stage,mainly in the degradation of lignin.Our results affirm that the influences of different groups of microorganisms on the humification process reflect in the differences in their uses of different materials and the functional groups at different incubation stages.These findings would advance the understanding of the relationship between microorganisms and soil humus.