Effects Of Multi-year Application Of Organic And Inorganic Fertilizers On Carbon Composition And Microbial Community In Tobacco Growing Soil

In order to explore the regular patterns in soil microbial community composition and organic carbon structure under different fertilization conditions for many years,the long-term positioning test of soil fertility that began in 2009 was used as the research object,and four field trials were set up: no fertilizer(CK),only apply chemical fertilizers(CF),combined application of chemical fertilizers and organic fertilizers(CFM),and only apply organic fertilizers(M),in order to provide basic data and theoretical support for fertilization of tobacco-planting sandy soil.The results of the research show that:1.Fertilization treatment significantly increased the content of inorganic nutrients,organic fertilizer treatment significantly increased SOC and lowered p H;organic fertilizer treatment significantly increased the content of DOC,MBC,POC,LOC and CPMI,DOC/SOC,SME,Among them,the increase of single application of organic fertilizer was the most significant.The 13C-NMR spectrum of SOC is mainly composed of alkyl carbon,carbohydrate carbon,aryl carbon and carboxyl carbon.The spectrum of single application of inorganic fertilizer is mainly determined by aryl carbon,and the aryl carbon and aryl oxygen carbon increase significantly.The aromaticity is improved;the spectrum of organic fertilizer treatment is mainly determined by alkyl carbons and carbohydrate carbons.The alkyl carbons and alkoxy carbons increase significantly,and the aliphatic carbons increase.The organic components of DOC in different fertilization treatments are mainly lignin and polycyclic aromatic hydrocarbons.The content of carbohydrates in the fertilization treatment increases,and the contents of protein,lignin and tannins are reduced.The aromatic structure of the ring decreases,the treatment with organic fertilizer increases,the weighted average value of the aromaticity(AI)of the treatment with inorganic fertilizer decreases,and the treatment with single organic fertilizer increases.2.Application of organic fertilizer treatment significantly improved soil cellulase(S-CL),invertase(S-SC),?-glucosidase(S-?-GC),polyphenol oxidase(S-PPD)and Peroxidase(S-POD)activity;Pearson correlation analysis shows that DOC,MBC,ROC and S-CL,S-SC,S-?-GC,S-PPD and S-POD activities are extremely significant Positive correlation;path analysis shows that S-CL,S-SC and S-?-GC directly affect the content of DOC,MBC and ROC,while the main indirect effects are S-PPD and S-POD;principal component analysis shows The comprehensive effects of different fertilization modes on active organic carbon components and enzyme activities can be divided into two groups: CK and CF treatments are a group,CFM and M treatments are a group;combined with the principal component analysis comprehensive score and variance analysis,different fertilization modes The order of affecting soil active organic carbon components and enzyme activity is M> CFM> CF> CK.3.Inorganic fertilizer and organic fertilizer treatments have negative and positive effects on the abundance and diversity of microbial communities,respectively,and have greater impact on bacterial communities than fungi.At the phylum level,bacteria mainly include Actinomycetes,Proteobacteria,Campylobacter phyta,etc.The relative abundance of Proteus phylum increased in organic fertilizer treatment,while the acid phylum and Campylobacter phylum decreased significantly;At the genus level,the relative abundance of Nitrospira in the fertilization treatment was significantly reduced,and the relative abundance of Streptomyces was significantly increased in the organic fertilizer treatment.At the phylum level,the most abundant fungal flora is the Ascomycota,and fertilization treatment reduces its relative abundance;at the genus level,Fusarium is the most abundant genus.In the organic fertilizer treatment,Fusarium and Penicillium are the most abundant genus.The relative abundance of Metarhizium anisopliae and Chaetomium increased significantly.PCo A analysis shows that different fertilization systems can change the communities of bacteria and fungi,and have a greater impact on bacteria than fungi.RDA analysis showed that the soil properties that have the greatest impact on bacterial community indicators are p H,aromatic oxygen carbon,and carbohydrate carbon;the soil properties that have the greatest impact on fungal community indicators are available phosphorus,available potassium,and alkali-hydrolyzable nitrogen.In summary,applying organic fertilizers for many years can increase organic carbon components and carbon-converting enzyme activity,optimize organic carbon structure,increase the abundance and diversity of microbial communities,replace some chemical fertilizers and improve soil fertility,and can provide a certain theoretical basis for the improvement of soil and the improvement of sustainable production capacity in Shandong tobacco areas.