Soil Quality Assessment And Microorganism Characteristic Responses To Fertilizer Treatments In Paulownia Fortunei Plantations

Paulownia sp.are indigenous to China and are among the fastest growing broad-leaved trees in China.Recently,commercial cultivation growing area has been increased rapidly in Hunan province and other subtropical area.How to evaluate soil fertility of paulownia plantations,and how soil microbial response to fertilizer,or even how to make paulownia grow faster are the issues that needed to be addressed as a matter of urgency.This thesis takes the P.fortunei plantations that comes from the central and north of Hunan province as the research project and 72 standard plots were set up for investigating the seven site factors and 23 soil indicators.Leading site factors which affect the stand volume of P.fortunei were chosen by Quantification Theory I.Principal component analysis(PCA),Pearson correlation analysis and Delphi method were used to select the minimum data set(MDS),Grey relation clustering analysis(GRCA)and soil quality index(SQI)were also used for assessing soil quality of P.fortunei plantations.Under a long-term management and monitoring as well as fixed-site trails by different fertilizer in Xiangyin Country,Illumina MiSeq sequencing,Biolog-ECO and canonical correspondence analyses(CCA)were used to research the microbial metabolisms and composition diversity of the soil microbial community.Impact of different fertilization on microbial enzyme activity and biomass were researched.The main results and conclusions were as follows:(1)Thickness of soil,the position of slope and mother rock are the leading site factors of the site quality and the MDS were screened to represent the soil quality of the P.fortunei plantations.Classification of the quality of soil were done and soil fertility evaluation were established.Soil quality of P.fortunei plantations can evaluated by available phosphorus,available potassium,available magnesium,available zine,available calcium,soil organic matter and catalase which were selected as the MDS.Eight different site conditions of P.fortunei plantations suggested that three soil quality classes could be defined:first class(SQI>0.86),second class(0.60<SQI<0.86),and third class(SQI? 0.60)which showed that P.fortunei can grow well in deep soil and red soils.In this study,the relationship was analyzed and a significant correlation was observed between SQI and SV.(2)SF can supplement the large amount of soil nutrient the P.fortunei needs,can effectively improve the stock volume of P.fortunei and can raise the contribution rate of soil fertilizer.NPK had the highest N,P and K than NPKM and SF,but it is not conducive to maintain the value of the chemical characters and the stand volume of P.fortunei.By applying SF,NPK and NPKM,the contribution of soil capacity decreased by 56.1%,43.7%and 44.00%after planting P.fortunei for six years.Meanwhile,the contribution of soil capacity and contribution ratio of fertilizer tends to be stable after four years of afforestation.(3)Illumina MiSeq showed that SF significant increase the bacteria abundance and decrease the fungi abundance,while NPK significant decrease the bacteria abundance and increase the fungi abundance.16S rRNA OTUs of the SF treatment is significantly higher than the CK,NPK and NPKM treatment,10.97%,21.96%and 8.23%,respectively,while 16S rRNA OTUs of the NPK significantly lower than CK and SF.ITS OTUs of the SF treatment is significantly lower than the CK,NPKM and NPK treatment,14.32%,15.39%and 20.32%,respectively,while ITS OTUs of the NPK significantly higher than CK,NPKM and SF.(4)The phyla firmicutes may be the dominant species under the SF,and Bacilli may be made the soil more fertile.The relative abundance of phyla firmicutes under specific fertilizer were higher than CK,NPK and NPKM 12%,219%and 75.6%,respectively,but no change has been found in NPK and NPKM treatments.The relative abundance of Bacilli under OM was higher than CK,NPK and NPKM 126.86%,241.82%and 123.20%.Firmicutes Bacilli may be the strain which directly affected by the SF.(5)SF improved the soil microbial enzyme activity and soil microbial biomass carbon,nitrogen and phosphorus significantly than NPK and NPKM.SF significantly increase the catalase,urease,acid phosphatase and invertase(p<0.05)than other fertilizer treatment.The catalase and acid phosphatase in NPK were significantly higher than CK(p<0.05),urease and invertase were significantly lower than SF(p<0.05).Compared with the CK,soil microbial biomass carbon and nitrogen were significantly raised in SF treatment(p<0.05).The microbial enzyme activity,and microbial biomass phosphorus were significantly raised in NPK treatment(p<0.05).There are close relationships between the microbial enzyme activity and microbial biomass Under SF treatment.Principal component analysis has showed that the SF has the greatest impact on soil microbial activity and chemical indicators.(6)SF had the highest efficiency of utilization of the carbon source and sugar is the main microbial carbon source.Microbial metabolic activity(Average Well Color Development)under SF treatment was significant difference higher than NPK,NPKM and CK(p<0.05),Compared with NPK,the AWCD of SF,NPKM and CK were improved by 19.66%,11.44%and 8.34%,respectively.Shannon,McIntosh and Simpson had significant differences between NPK and SF(p<0.05),but CK and NPKM not.Shannon,McIntosh and Simpson under SF were improved at 2.87%?18.69%and 1.05%than NPK,respectively.The utilization rate of amino acids,carboxylic acids,sugars,polyamine and polymer under SF were the highest.(7)Available phosphorus and organic matter were the most strongly related to bacteria and fungi community composition(p<0.01).The first and second CCA axes explained 56.90%of the total bacterial variation.The first axis(CCA1)explained 34.6%of the total variation of bacterial phyla;AP and SOM were strongly correlated with CCA1(0.63 and 0.62).The first axis(CCA1)explained 88.20%of the total variation of fungi phyla;AP and SOM were strongly correlated with CCA1(0.68 and 0.67).