Effects of tobacco-stalk biochar returning on soil nutrients，the structure and functioning of bacterial communities in tobacco-planting yellow-brown fields
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摘要: 【目的】明确烟秆生物炭对植烟黄棕壤养分、细菌群落结构与功能的影响，为提高烟秆的资源化利用提供理论依据。【方法】基于大田试验，比较不同用量烟秆生物炭（0、5、15、20和40 t/ha）施用4年后烟田土壤养分指标及细菌丰度变化；采用16S rDNA序列高通量测序技术和PICRUSt基因预测方法，分析耕层土壤细菌群落结构、多样性及代谢功能变化。【结果】随着生物炭施用量的增加，土壤pH、有机质、总氮、有效磷、速效钾含量及细菌丰度呈增加趋势。主坐标分析（PCoA）和聚类分析结果表明，施用生物炭改变了细菌群落组成。生物炭用量在15 t/ha时，土壤细菌OTU丰富度及Alpha多样性指数最高；在门水平上，变形菌门（Proteobacteria）、放线菌门（Actinobacteria）相对丰度较低，而芽单胞菌门（Gemmatimonadetes）、绿弯菌门（Chloroflexi）、浮霉菌门（Planctomycetes）和硝化螺旋菌门（Nitrospirae）相对丰度较高；在属水平上，芽单胞菌属（Gemmatimonas）、黄色土源菌属（Flavisolibacter）和Roseiflexus相对丰度较高。冗余分析（RDA）结果表明，生物炭用量与土壤拟杆菌门显著正相关（P<0.05，下同），与酸杆菌门显著负相关。PICRUSt功能预测表明，施用生物炭增加了与土壤碳代谢相关的细菌基因丰度。【结论】贵州植烟黄棕壤施用烟秆生物炭后，土壤养分、烤烟农艺性状和经济性状指标均有提升，土壤细菌群落丰富度及多样性显著提高，土壤细菌碳代谢能力增强，对改善烟田土壤微生态具有积极作用。以15 t/ha烟秆生物炭作用效果较好，可在生产上推广应用。Abstract: 【Objective】 In order to explore the effects of tobacco-stalk biochar（BC）on soil nutrients the structure and functioning of bacterial communities in tobacco-planting yellow-brown fields， and provide theoretical basis for the utilization of tobacco stalk.【Method】 A field experiment with different biochar dosages（0， 5， 15， 20， 40 t/ha）was set up to compare the changes of soil nutrient indexes and bacterial abundance of tobacco field after four years’application. The 16S rDNA high-throughput sequencing and PICRUSt gene prediction analysis were used to decipher soil community composition，diversity and metabolic function.【Result】The results showed that soil pH， organic matter， total nitrogen， available phosphorus， available potassium and the abundance of soil bacteria significantly increased with the dosage of biochar application. The results of principal coordinate analysis（PCoA）and cluster analysis show that soil bacterial community composition was significantly altered by the biochar application. When the amount of tobacco-stalk biochar was 15 t/ha， bacteria OTU richness and Alpha diversity indexes were higher than other treatments. At the phylum level， the relative abundance of Proteobacteria and Actinobacteria was lower under 15 t/ha than other treatments， but those of Gemmatimonadetes， Chloroflexi， Planctomycetes and Nitrospirae were high. At the genus level， the relative abundance of Gemmatimonas， Flavisolibacter，Roseiflexus was higher under 15 t / ha than other treatments. Redundancy analysis（RDA） analysis showed that biochar application dosage was significantly positively correlated with the relative abundance of Bacteroidetes （P<0.05，the same below）， while negatively correlated with Acidobacteria. PICRUSt functional prediction analysis suggested that biochar application increased the functional gene abundance related to soil carbon metabolism in bacterial community.【Conclusion】 After applying tobacco-stalk biochar to the yellow-brown tobacco-planting soil in Guizhou，soil nu-trients，agronomic and economic indicators of flue-cured tobacco are improved，and the richness and diversity of soil bacterial communities are significantly increased. The carbon metabolism ability of soil bacteria is enhanced，which has a positive effect on improving the soil microecology of tobacco fields. In sum，the effect of using 15 t/ha tobacco-stalk biochar isrelatively better and can be popularized in tobacco production.
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