Effects Of Fertilization Management On Ammoniaoxidizing Microorganisms In Guizhou Acidic Tea Soil And Evaluation Of Soil Quality

Tea is one of the important economic crops in my country.The area of tea gardens and the output of tea both rank first in the world.Guizhou Province has become the province with the largest area of tea gardens in my country because of its good mountainous climate conditions.As a human factor,fertilization management is one of the important ways to affect the yield of tea gardens.Different fertilization measures and management modes will have an important impact on the quantity,structure and diversity of soil microbial communities.Ammonia-oxidizing microorganisms,which include Ammonia-Oxidizing Archaea（AOA）and Ammonia-Oxidizing Bacteria（AOB）,play a crucial role in soil microorganisms.Their participation in ammonia oxidation is the rate-limiting process of the entire nitrification process,and this process is influenced by various factors such as the physical and chemical properties of the soil.Despite previous studies on the effects of fertilization patterns on AOA and AOB communities,the results have been inconsistent.Therefore,further research is needed to determine the relative contributions of AOA and AOB to soil nitrification under different fertilization managements.This study focused on tea gardens in Meitan County,Guizhou Province,also known as’the first county of tea industry in Guizhou.’The researchers utilized a high-throughput sequencing platform to investigate the impact of various fertilization management techniques on the abundance,community structure,and diversity of tea garden soil AOA and AOB.The study’s findings shed light on the changes in ammonia-oxidizing microbial communities in response to different fertilization conditions.These results provide a foundation for further research on the regulation of soil nitrogen cycles by ammonia-oxidizing microorganisms in tea gardens.This study aimed to investigate the expression of AOA and AOB in acidic tea soil under different fertilization management（straw compost MT1,organic fertilizer MT2,straw compost+farmyard manure MT3,no fertilization MT4）by constructing the clone library of ammonia monooxygenase gene（amo）.The study evaluated the abundance,community structure,and diversity response,and assessed the impact of different fertilization management on regional soil quality.The main findings of the research are as follows:1.The physical and chemical properties of soil samples were analyzed to determine the nutrient status of tea garden soil under different fertilization management.The soil p H values of MT1 with straw mulching,MT3 of straw mulching+farmyard manure,and MT4 without fertilization were found to be between 4.5 and 5.5.The soil total nitrogen content of MT2 and MT3 samples with organic fertilizer and farmyard manure respectively showed significant differences,with MT3 of farmyard manure application having the highest content,followed by MT2 of organic fertilizer application,MT1 of straw composting,and MT4 of non-fertilization.The areas with different soil available phosphorus content showed MT3>MT2>MT1>MT4.2.The study analyzed the community structure and diversity of ammonia oxidizing microorganisms in collected samples.Thaumarchaeota was identified as the main source of AOA in the study area.Candidatus Nitrosotalea devanaterra,belonging to the genus Candidatus Nitrosotalea,was found to have the highest relative abundance in acidic tea garden soil,with MT3>MT2>MT1>MT4.Candidatus Nitrososphaera gargensis Ga9.2,belonging to the genus Nitrososphaera,had the highest relative abundance in MT4 without fertilization,showing MT4>MT1>MT2>MT3,which is the opposite of the former.The application of fertilization management resulted in a shift in the dominant bacteria in the tea garden soil of the study area.Specifically,there was a transformation from Ca.Nitrososphaera gargensis Ga9.2 to Ca.Nitrosotalea devanaterra,which accounted for 17.3%and 74.7%of AOA,respectively.3.The soil AOB in the study area mainly come from Nitrosospira of the Proteobacteria.The relative abundance of Nitrosospira sp.is higher,the most abundant in the straw composting+farmyard manure MT3 sample site,and the lowest in the organic fertilizer MT2.The expression was MT3>MT4>MT1>MT2.Nitrosospira multiformis ATCC 25196 was detected in addition to Nitrosospira sp.The former was mainly found in the MT2 sample site where organic fertilizer was applied,with expression levels in the order of MT2>MT1>MT4>MT3.In total,Nitrosospira sp.and Nitrosospira multiformis ATCC 25196 accounted for 74.1%and 17.8%of AOB content,respectively.4.Pearson correlation analysis was carried out on the physical and chemical properties of the soil in the study area,the number of ammonia-oxidizing microbial communities,and the diversity index.The results showed that the Chao1,ACE community richness index and Shannon community diversity index of AOA and AOB in MT1 and MT3 were higher than those in MT2 and MT4,indicating that straw composting and farm manure application can effectively increase the ammonia oxidizing microorganisms.The study found significant differences in the ACE indexes of AOA and AOB communities across the four sampling sites,indicating unique species at each site.The MT2 site had a lower Shannon index,which was likely due to the use of organic fertilizers.Pearson correlation analysis showed that the AOA community’s richness was negatively correlated with NH₄⁺-N and NO₃^--N contents,while community diversity was positively correlated with p H and C/P_avi.The AOA community had low affinity towards NH₄⁺-N and NO₃^--N,and ammonium content did not significantly affect community diversity.5.Using the soil quality index method（SQI）to carry out the quality evaluation of the acidic tea garden soil environment in the research area.The results of the study showed that MT1 with straw composting had the highest score of soil environmental quality,which ranked first in the evaluation score,followed by MT3 with farmyard manure and MT2 with organic fertilizer,and MT4 with no fertilization had the lowest score,which may be related to different fertilization.The impact of management measures on the soil environment and the structure and diversity of ammonia-oxidizing microbial communities were related.Generally speaking,fertilization management can improve the soil nutrient environment in tea gardens,and mulching straw can alleviate soil acidification and increase the richness and diversity of ammonia-oxidizing microbial communities,but it will reduce the number of unique OTUs of AOA and AOB,and change the abundance of dominant species;Soil p H,available phosphorus and NO₃^--N,NH₄⁺-N content are the key factors affecting the microbial abundance of nitrogen cycle in tea soil.Fertilization management increases soil nutrients,especially available phosphorus content,and changes the community structure and diversity of ammonia-oxidizing microorganisms,the response of AOA to fertilization management was more sensitive than that of AOB community.