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Changes In Functional Diversity And Structure Of Microbial Community Of Soil Aggregates From Upland To Paddy Field In Northeast China

Posted on:2021-05-04Degree:MasterType:Thesis
Country:ChinaCandidate:M C ZhaoFull Text:PDF
GTID:2370330605964811Subject:Plant Nutrition
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Black soil in Northeast China is a precious soil resource with high productive potential.Driven by economic interests,a part of upland black soil has been changed to paddy field(abbreviated as "land to paddy")in Northeast China.This transformation of land use has changed the soil ecological environment,which will inevitably lead to change in the structure of microbial communities.The formation of soil aggregates is a very complex process,in which microorganisms play a very important role,and the two are inseparable.For this reason,this paper takes upland in the northeast black soil(mainly planting corn)and the paddy field after "land to paddy" as the research object.The physical and chemical properties,soil enzyme activities,the functional diversity and structure of soil aggregates in upland and paddy field were analyzed,and the difference of microbial community structure and activity of soil aggregates in upland and paddy field were compared.The purpose of this paper is to reveal the change of microecology in soil aggregates after replanting upland to paddy field of black soil in Northeast China.The main results are as follows:(1)After changing from land to paddy,the number of soil water-stable microaggregates increased by more than 50%;the content of organic carbon(SOC)in soil aggregates was significantly increased,and the content of total nitrogen(TN)in soil aggregates was decreased.The contents of organic carbon(SOC)and total nitrogen(TN)of all aggregates in upland and paddy field were the highest in macroaggregates and the lowest in silt+clay;The activities of urease and(3-glucosidase in upland aggregates were higher than those in paddy field aggregates,but there was no significant difference in protease activities.The activities of urease,cellulase and ?-glucosidase in different particle size aggregates in paddy field showed a certain regularity,that is,large aggregates>silt+clay>microaggregates,while microorganisms in upland had no regularity;(2)The average well color development(AWCD)of soil microbial community in upland and paddy field in all soil aggregates from high to low were upland silt+clay>upland macro-aggregates>upland micro-aggregates>paddy field macro-aggregates>paddy field silt+clay>paddy field micro-aggregates.After changing from land to paddy,the microbial carbon source utilization ability of all soil aggregates were significantly reduced,especially amino acids and carbohydrates.Principal component analysis further showed that the microbial function of different particle size aggregates in upland and paddy fields changed,and the main carbon sources for differentiation of PC1 and PC2 were amino acids,carbohydrates and carboxylic acids;(3)The results of soil aggregate bacterial community diversity index analysis showed that the richness and diversity of soil aggregate bacterial community were increased after land to paddy.Among the upland aggregates,except for Shannon index,the ACE index,PD index and Chaol index of microaggregates were the highest,while those of microaggregates were the lowest,while those of PD index,ACE index,Shannon index and Chaol index of large aggregates in paddy field were the highest,and those of silt+clay were the lowest;(4)The results of principal component analysis showed that there were great differences in the composition of bacterial community structure of all soil aggregates in upland and paddy field.The bacterial community composition of all aggregates in paddy field was quite different,and the similarity of bacterial community composition of all soil aggregates in upland was high;(5)At the phylum level,Proteobacteria,Bacteroidetes,Actinobacteria,Acidobacteria,Chlorofleixi,Thaumarchaeota,Firmicutes,Verrucomicrobia,Gemmatimonadetes and Nitrospirae were the main aggregates in upland and paddy feild.There were great differences in the composition of grain diameter aggregates at genus level between upland and paddy field.Geobacter was dominant in paddy field,and Rhodanobacter,Bacillus and Nitrosopira were dominant in upland.The main differential species affecting soil aggregates in upland and paddy field were Anaerolineaceae,Clostridia,Nitrospira,Xanthomonadaceae,Nitrosomonadaceae and Gemmatimonadaceae;(6)At the bacterial community phylum level,soil aggregates in paddy field were positively correlated with organic carbon,and total nitrogen was positively correlated with silt+clay and large aggregates in upland.To sum up,the microbial community structure of soil aggregates was changed after land to paddy,and the microecological changes of soil aggregates after land to paddy were analyzed comprehensively.
Keywords/Search Tags:black soil, upland to paddy field, soil aggregate, microbial community structure, high-throughput sequencing
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