生物炭连续施用对旱地红壤细菌群落结构的影响

为揭示生物炭对于旱地红壤土壤改良的长期影响，通过连续 8 年的田间小区试验，设置 3 个试验处理:不施生物炭(CK)、750 kg·hm-2 生物炭(C1)和 1500 kg·hm-2 生物炭(C2)。研究了生物炭连续施用对旱地红壤土壤理化性质、细菌群落结构特征的影响，并分析了影响细菌群落结构特征的理化因子。结果表明，变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、放线菌门(Actinobacteria)、芽单胞菌门(Gemmatimonadetes)、绿弯菌门(Chloroflexi)和拟杆菌门(Bacteroidetes)6 个门类是所有处理的优势菌群；与 CK 相比，施用生物炭可以显著提高土壤 pH 0.11 ～ 0.29 个单位、碳氮比 7.85% ～ 8.21% 和有机质 8.70% ～ 11.97%，而显著降低土壤硝态氮含量 10.57% ～ 38.63%。主成分分析表明施用生物炭显著改变了细菌群落结构组成(R=0.52，P=0.02)；在门水平上，与 CK 处理相比，C1 处理放线菌门的相对丰度显著增加 24.73%，C2 处理拟杆菌门的相对丰度显著增加 39.03%，而 C1 处理的绿弯菌门显著低于 CK，降幅为 18.90%。冗余分析表明，土壤硝态氮(R2=0.77，P<0.01)和 pH(R2=0.54，P<0.05)是细菌群落结构变异的主导性环境因子；细菌群落与环境因素相关性表明，优势菌群受土壤 pH、有机质、溶解性有机碳、硝态氮、铵态氮和碳氮比的影响。综上，生物炭施用 8 年后对土壤环境因子有显著的影响，其中某些关键环境因子的改变驱动了土壤细菌群落的生态演替。

Effects of continuous biochar application on bacterial community structure in upland red soil

To reveal the long-term effects of biochar on soil improvement in dryland red soil, a field experiment was conducted with three treatments: no biochar(CK), 750 kg·hm-2 biochar(C1)and 1500 kg·hm-2 biochar(C2)after 8 years of biochar application. The effects of biochar application on bacterial community structure characteristics and soil physicochemical property in dryland red soil were studied, and the physicochemical factors affecting the bacterial community structure characteristics were analyzed. Results showed that Proteobacteria, Acidobacteria, Actinobacteria, Gemmatimonadetes, Chloroflexi and Bacteroidetes were the dominant bacteria. Compared with CK, biochar application significantly increased soil pH, C/N and organic matter by 0.11-0.29, 7.85%-8.21% and 8.70%-11.97%, respectively, while soil nitrate nitrogen content was decreased by 10.57%-38.63%. Principal component analysis showed that the application of biochar significantly changed the composition of bacterial community structure(R=0.52, P=0.02). Compared with CK, the Actinobacteria of C1 treatment was significantly higher than CK by 24.73%, and the Bacteroidetes of C2 treatment was significantly higher than CK by 39.03%, while the Chloroflexi of C1 treatment was significantly lower than CK by 18.90%. Redundancy analysis showed that soil nitrate nitrogen(R2=0.77, P<0.01)and pH(R2=0.54, P<0.05)were the dominant environmental factors for the variation of bacterial community structure. The correlation analysis between bacterial communities and environmental factors showed that the dominant bacteria were also affected by soil pH, organic matter, dissolved organic carbon, nitrate nitrogen, ammonium nitrogen and C/N. In summary, the application of biochar for 8 years had a significant impact on soil environmental factors, and the changes of some key environmental factors drove the ecological succession of soil bacterial community.