The Effects Of Straw Residue Incorporation On Fungal Communities In Lime Concretion Black Soil

In recent years,there are increasing attentions about the soil managements on the improvement of soil fertility including conservation tillage and straw residue incorporation.Many researches have studied the changes of the soil chemical properties.However,there is still a knowledge gap about the impacts of conservation tillage and straw residue incorporation on the soil microorganisms.Fungi as a decomposer in soil are important drivers of biogeochemical cycles in terrestrial ecosystems and participate in most nutrient transformation processes in the soil.These processes make a tight connections between plant and soil,which influence plant healthy.Besides,the interactions of soil,plant and microorganisms make a big variations of the soil physical,chemical and biological properties between non-rhizosphere and rhizosphere soil.We conducted a preliminary analyses of the diversity and composition of fungal communities in non-rhizosphere and rhizosphere soil from a winter-maize double cropping system field experiment in Mengcheng,Anhui province.Soil samples were taken from the non-rhizosphere and rhizosphere soil at the bell stage of maize and heading stage of wheat with six treatments: control(CK,conventional tillage without straw retention),conventional tillage combined with straw retention(SR),reduced tillage combined with straw retention(RSR)and no tillage combined with straw retention(NSR),conventional tillage with born straw return(BSR)and conventional tillage with incomplete born straw return(ICR).The fungal ITS gene fragments were amplified from each soil sample both in non-rhizosphere and rhizosphere soil and sequenced using high-throughput sequencing on Illumina Miseq platforms.The results of maize bell stage:(1)Straw residue incorporation had no significantly impact on the soil pH both in non-rhizosphere and rhizosphere soil.RSR,NSR and ICR significantly increased soil organic matter(SOM)both in non-rhizosphere and rhizosphere soil.RSR,NSR significantly increased total nitrogen(TN)in rhizosphere soil,and ICR significantly increased TN both in non-rhizosphere and rhizosphere soil.ICR had the highest increasing effect on SOM and TN both in non-rhizosphere and rhizosphere soil.SR,RSR,NSR,ICR can enchance soil available nitrogen(AN).Straw residue incorporation had no influnence on soil available phosphorus(AP)content(except RSR),but can significantly increase soil available potassium(AK)content.(2)SR significantly decreased fungal richness and diversity in non-rhizosphere soils,while only decreased fungal diversity in rhizosphere soil.RSR,NSR,BSR and ICR hadno significantly influence of fungal richness and diversity both in non-rhizosphere and rhizosphere soil.(3)Soil fungi are distributed in 5 known phyla,20 known classes and 332 known genera including Ascomycota,Basidiomycota,Chytridiomycota,Glomeromycota and Zygomycota with a higher abundance of Ascomycota?Basidiomycota?Zygomycota in non-rhizosphere and rhizosphere soil.No Rank and Unclassified Fungi accounted for25.6%~68.0% and 44.8%~62.3% of relative abundance of total sequences in non-rhizosphere and rhizosphere soils which had no significantly correlation to any soil phy-chemical properties.SOM,TN,AN had significantly correlation to some groups at phylum level.The dominant fungal phyla across all samples were Ascomycota and Basidiomycota,while,the relative abundance of the dominant phyla were affected by different treatment both in non-rhizosphere and rhizosphere soil.There were 6 kinds of the dominant fungal classes across all treatment soil,including Agaricomycetes,Dothideomycetes,Eurotiomycetes,Glomeromycetes,Sordariomycetes and Tremellomycetes.Based on the similarities of community compositions at the level of fungal genera,RSR in non-rhizosphere was clustered into one group,while,others were clustered into another group.The results of wheat heading stage:(1)Straw residue incorporation had no significantly impact on the soil pH both in non-rhizosphere and rhizosphere soil(except RSR).SR,RSR,and ICR significantly increased SOM both in non-rhizosphere and rhizosphere soil,as well as NSR in rhizosphers and BSR in non-rhizosphere soils.ICR significantly increased TN both in non-rhizosphere and rhizosphere soil,as well as BSR in non-rhizosphere soil and SR,RSR and NSR in rhizosphere soil.ICR had the highest increasing effects on SOM and TN both in non-rhizosphere and rhizosphere soil.BSR can enchance soil AN.Straw residue incorporation had no influence on soil AP content,but can significantly increase soil AK content.(2)BSR significantly decreased fungal diversity in rhizosphere soil.While other treatments had no significantly influences of fungal richness and diversity both in non-rhizosphere and rhizosphere soil.(3)Soil fungi are distributed in 5 known phyla,17 known classes and 165 known genera including Ascomycota,Basidiomycota,Chytridiomycota,Glomeromycota and Zygomycota with a higher abundance of Ascomycota ? Basidiomycota and Zygomycota both in non-rhizosphere and rhizosphere soil.Unclassified Fungi and Unidentified werealso detected and their relative abundance had no significantly correlation to any soil phy-chemical properties.Soil pH,SOM,TN,AN,AP and AK had significantly correlation to some groups at phylum level.The dominant fungal phyla across all samples were Ascomycota and Basidiomycota and Zygomycota,while,the relative abundance of the dominant phyla were affected by different treatment both in non-rhizosphere and rhizosphere soil.There were 4 dominant fungal classes across all treatment soil,including Agaricomycetes,Dothideomycetes,Sordariomycetes and Tremellomycetes,while,Dothideomycetes,Sordariomycetes were the most dominant classes among all treatments.Based on the similarities of community compositions at the level of fungal genera,RSR,R_RSR and R_SR were clustered into one group,while,others clustered into another group.