有机物料施用对潮土活性有机碳及微生物群落组成的影响

Effect of Application of Organic Materials on Content of Labile Organic Carbon and Composition of Microbial Community in Fluvio-Aquatic Soil

土壤活性有机碳是土壤中周转较快,对管理措施反应较为敏感的碳组分,但不同有机物料的影响效应及其微生物机制尚不清楚。比较小麦-玉米轮作条件下,麦季秸秆还田(R)和木本泥炭(MT)连续施用2年对玉米收获期潮土可矿化有机碳(PCM)、微生物生物量碳(MBC)、可溶性有机碳(DOC)、易氧化有机碳(ROC)、颗粒有机碳(POC)的影响,评估其与细菌和真菌群落组成之间的关系。结果表明:与不施用任何有机物料的CK相比,R处理及秸秆和木本泥炭联合施用(RMT)的DOC含量分别显著增加30.33%和31.46%;MT和RMT处理的POC含量分别显著增加104.86%和64.78%;而PCM、MBC、ROC在处理之间无显著变化。高通量测序发现,4个处理之间的细菌群落组成无显著变化,而真菌发生显著变化,并主要受制于POC、DOC、NH_(4)^(+)-N变化。相关性分析发现,DOC和POC均与转化酶活性显著正相关。DOC和转化酶均在R处理中显著增加,与Trichoderma peltatum和Trichoderma aerugineum丰度显著正相关;DOC同时与能促进根系分泌物生成的Pyrenochaeta unidentified丰度显著正相关,它在RMT处理中显著增加。POC和转化酶均与Cladorrhinum flexuosum和Basidiobolus ranarum显著负相关,该俩微生物在MT处理中显著降低,而在RMT中仅Cladorrhinum flexuosum显著降低;POC和转化酶均与Chaetothyriales unidentified显著正相关,它们在RMT处理中显著升高。施用秸秆或木本泥炭分别改变了潮土不同活性有机碳的含量,可能是因为两种有机物料施用分别产生了不同的真菌群落组成,进而改变了功能微生物丰度及相关酶活性。

【Objective】Soil labile organic carbon (LOC) is a soil component that is quite quick in turnover and quite sensitive to soil management practices.However,it is not clear how application of organic materials or manures LOC and their microbial mechanisms.【Method】In this study,a field experiment was designed to have wheat and maize planted in rotation and conducted to explore effects of returning wheat straw (R) and applying woody peat (MT) for two years in a row on potential carbon mineralization (PCM),microbial biomass carbon (MBC),dissolved organic carbon (DOC),readily oxidizable carbon (ROC) and particulate organic carbon (POC) in fluvo-aquic soil at the harvesting stage of the second maize crop.【Result】Compared with CK without any organic manure,Treatment R (returning of wheat straw) and Treatment RMT (returning of wheat straw plus application of wood peat) was 30.33%and 31.46%higher in DOC and 104.86%and 64.78%higher in POC,respectively.However,the treatments did not have much effect on PCM,MBC and ROC.High-throughput sequencing analysis shows that the treatments did not have much impact on soil bacterial community composition,but did have on fungi,which was mainly attributed to changes in POC,DOC and NH_(4)^(+)-N.Correlation analysis shows that DOC and POC were significantly and positively related to invertase activity.Both DOC and invertase increased significantly in Treatment R and were significantly and positively related to the abundance of Ttrichoderma peltatum and Trichoderma aerugineum.At the same time,DOC was significantly and positively related to the abundance of Pyrenochaeta unidentified,capable of promoting formation of root secretions,and Pyrenochaeta unidentified increased significantly in Treatment RMT.Both POC and invertase were significantly and negatively related to Cladorrhinum flexuosum and Basidiobolus ranarum,both of which decreased significantly in Treatment MT,while only Cladorrhinum flexuosum did in Treatment RMT.POC and invertase were also significantly and positively related to Chaetothyriales unidentified,and increased significantly in Treatment RMT.【Conclusion】All the findings demonstrate that both returning of wheat straw and application of woody peat alter the content of labile organic carbon,regardless of type,which may be attributed to the effects of the two practices affecting,separately,composition of the fungal community,thus altering abundance of the functional microbes and activity of relevant enzymes.