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Effects Of Cotton Straw Biochar On Soil Microbial Community Composition And Function

Posted on:2021-03-01Degree:MasterType:Thesis
Country:ChinaCandidate:J WangFull Text:PDF
GTID:2370330620972779Subject:Agricultural Resources and Environment
Abstract/Summary:PDF Full Text Request
[Objective]Biochar has great potential in soil carbon fixation and nitrogen cycling regulation in farmland.Microorganisms are the main drivers of soil carbon and nitrogen transform,but the effect of biochar on soil microbial carbon and nitrogen metabolism is not fully understood.Taking cotton straw and its biochar as the research object,the differences of the effects of straw and its biochar on soil organic carbon and nitrogen content were expounded.The response of soil microbial community composition to straw biochar was analyzed,and the changes of metabolic activity and function of microbial community were discussed.[Methods]A field experiment was conducted at a positioning test station of BeiQuan town,Shihezi from 2017 to 2018.Four treatments were set as?1?Control?CK?,?2?N fertilizer application at 300 kg·ha-1?N?,?3?Cotton straw?N+ST,N fertilizer application plus cotton straw?,?4?Cotton straw biochar?N+BC,N fertilizer application plus cotton straw biochar?.Used Biolog analyze the metabolic activity of microbial community,the soil bacterial community were studied used 16s rRNA sequencing,and metagenomics analysis reveals the soil microbial community function and the metabolic pathways.[Result]?1?Nitrogen fertilizer application for 5 years reduced soil organic carbon content,while nitrogen fertilizer application plus cotton straw?N+ST?and N fertilizer application plus cotton straw biochar?N+BC?increased TOC components.N+ST and N+BC treatment increased the TOC content by 8.9%and 48.4%.The organic nitrogen in N+ST and N+BC treatment were increased by 16.3%and 24.8%,respectively.The content of inorganic nitrogen,acidolysis ammonium nitrogen and amino sugar nitrogen components in N+BC were significantly higher than N+ST,while N+ST mainly increased the amino acid nitrogen component.?2?The metabolic activities of soil microorganisms?AWCD?N+ST was the highest,followed by N+BC treatment,which was significantly higher than that in N treatment.N+ST mainly increased the metabolic activity of carbohydrates sources and Amines sources.N+BC mainly increased the metabolic activity of Phenols sources and Polymers sources.?3?16s rRNA sequencing results showed that N+ST and N+BC significantly improved the diversity of soil bacterial community.N+ST treatment significantly improved the relative abundance of Nocardioides,Ilumatobacter,Lysobacter,Variibacter.The relative abundance of Nitrospira,RB41,Haliangium,H16,Ochrobactrum,Vibrionimonas increased significantly after N+BC application.The correlation analysis showed that Nocardioides,Ilumatobacter,Lysobacter,and Variibacter were positively correlated with carbohydrates,amino acids and amines.There was a significant positive correlation between the Nitrospira,Ochrobactrum,and Vibrionimonas.?4?Metagenomic analysis of soil microorganisms showed that the relative abundance of bacteria accounted for 96.98%of the total soil microorganisms,while that of archaea and eukaryotes accounted for 1.20%.N+ST treatment significantly improved the diversity of soil microbial community composition and the relative abundance of bacteria and eukaryotes in N+ST treatment was significantly higher than that in N+BC treatment.The relative abundance of archaea in N+BC treatment was significantly higher than that in N+ST treatment.?5?Metagenomic functional annotation of CAZy in soil microbial showed that the relative abundance of CBMs,CEs,GHs and PLs genes?involved in carbohydrate degradation?treated by N+ST significantly higher than that of N+BC and N treatment,but the relative abundance of GTs gene?carbohydrate synthase?was significantly decreased.EggNOG functional annotation found that N+ST increased the relative abundance of carbohydrate transport and metabolic functional genes,and decreased amino acid transport and metabolic functions.The N+BC treatment increased the abundance of amino acid transport and metabolic function genes.?6?The difference analysis of the enrichment of carbon and nitrogen metabolism pathway in KEGG were analysed.The carbon metabolism pathway enrichment in N+ST treatment was significantly higher than that in N+BC treatment,and N+BC significantly improved the nitrogen metabolism pathway enrichment.N+ST treatment significantly increased the relative abundance of TCA cycle genes of soil organic carbon degradation,and N+BC treatment significantly increased the gene abundance of prokaryotic carbon fixation pathway.The gene abundance of aminophosphate synthase treated with N+ST was significantly higher than that in N and N+BC treatment,while that of glutamate synthase,glutamate dehydrogenase and glutamine synthase significantly increased in N+BC treatment.From the perspective of carbon metabolism pathway,N+ST treatment significantly increased the enzyme gene abundance related to the TCA cycle,while N+BC treatment increased the gene abundance related to carbon fixation in prokaryotes.Analysis of the nitrogen metabolism pathway revealed that the gene abundance of carbamyl phosphate synthetase treated with N+ST was significantly higher than that of N+BC treatment,while the gene abundance of glutamate dehydrogenase,glutamate synthase and glutamine synthase significantly increased in N+BC treatment.[Conclusion]Cotton straw increased the diversity of soil microbial community and the metabolic activity of microbial carbon source,increased the relative abundance of carbon degrading enzyme genes,and promoted the degradation of simple organic carbon source.Cotton straw biochar increased changed soil microbial community composition,increased the abundance of carbon fixation and amino acid synthesis pathway enzyme genes,beneficial to the accumulation of soil organic carbon and nitrogen.
Keywords/Search Tags:Cotton straw biochar, Microbial biological activity, Bacterial community composition, Metagenomics, Carbon and nitrogen metabolic pathways
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