title: Biochar decreased microbial metabolic quotient and shifted community composition four years after a single incorporation in a slightly acid rice paddy from southwest China.
abstract: While numerous studies both in laboratory and field have showed short term impacts of biochar on soil microbial community, there have been comparatively few reports addressing its long term impacts particular in field condition. This study investigated the changes of microbial community activity and composition in a rice paddy four years after a single incorporation of biochar at 20 and 40t/ha. The results indicated that biochar amendment after four years increased soil pH, soil organic C (SOC), total N and C/N ratio and decreased bulk density, particularly for the 40t/ha treatment compared to the control (0t/ha). Though no significant difference was observed in soil basal respiration, biochar amendment increased soil microbial biomass C and resulted in a significantly lower metabolic quotient. Besides, dehydrogenase and β-glucosidase activities were significantly decreased under biochar amendment relative to the control. The results of Illumina Miseq sequencing showed that biochar increased α-diversity of bacteria but decreased that of fungi and changed both bacterial and fungal community structures significantly. Biochar did not change the relative abundances of majority of bacteria at phylum level with the exception of a significant reduction of Actinobacteria, but significantly changed most of bacterial groups at genus level, particularly at 40t/ha. In contrast, biochar significantly decreased the relative abundances of Ascomycota and Basidiomycota by 11% and 66% and increased the relative abundances of Zygomycota by 147% at 40t/ha compared to the non-amended soil. Redundancy analysis (RDA) indicated that biochar induced changes in soil chemical properties, such as pH, SOC and C/N, were important factors driving community composition shifts. This study suggested that biochar amendment may increase microbial C use efficiency and reduce some microorganisms that are capable of decomposing more recalcitrant soil C, which may help stabilization of soil organic matter in paddy soil in long term.
authors.affiliation: Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China.
authors.forename: Jufeng
authors.initials: J
authors.lastname: Zheng
authors.affiliation: Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; Zhejiang Provincial Key Laboratory of Carbon Cycling in Forest Ecosystems and Carbon Sequestration, School of Environmental and Resource Sciences, Zhejiang A & F University, Lin'an, Hangzhou 311300, China. Electronic address: junhui5@126.com.
authors.forename: Junhui
authors.initials: J
authors.lastname: Chen
authors.affiliation: Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China.
authors.forename: Genxing
authors.initials: G
authors.lastname: Pan
authors.affiliation: Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China.
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Liu
authors.affiliation: Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China.
authors.forename: Xuhui
authors.initials: X
authors.lastname: Zhang
authors.affiliation: Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China.
authors.forename: Lianqing
authors.initials: L
authors.lastname: Li
authors.affiliation: Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China.
authors.forename: Rongjun
authors.initials: R
authors.lastname: Bian
authors.affiliation: Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Cheng
authors.affiliation: Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, Nanjing 210095, China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing 210095, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Jinwei
mesh_terms: D000383:Agriculture / Q000379:methods*; D018407:Bacterial Physiological Phenomena; D001673:Biodegradation, Environmental; D018533:Biomass; D002606:Charcoal / Q000008:administration & dosage*; D002681:China; D005658:Fungi / Q000502:physiology*; D064307:Microbiota; D012275:Oryza / Q000254:growth & development; D012621:Seasons; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
chemical_list: D012987:Soil; C540010:biochar; D002606:Charcoal
keywords: Enzyme activity; Illumina Miseq sequencing; Microbial biomass; Microbial community composition; Soil respiration