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Taxon-specific responses of soil microbial communities to different soil priming effects induced by addition of plant residues and their biochars

Su, Peng, Lou, Jun, Brookes, Philip C., Luo, Yu, He, Yan, Xu, Jianming
Journal of soils and sediments 2017 v.17 no.3 pp. 674-684
Acidobacteria, Actinobacteria, Ascomycota, Basidiomycota, Chloroflexi, Chytridiomycota, Euryarchaeota, Firmicutes, Gemmatimonadetes, Planctomycetes, Proteobacteria, Verrucomicrobia, Zygomycota, bacteria, biochar, carbon dioxide, cluster analysis, corn, feedstocks, fungi, high-throughput nucleotide sequencing, microbial communities, mineralization, phylogeny, plant residues, soil, soil microorganisms, taxonomy
PURPOSE: This work investigated changes in priming effects and the taxonomy of soil microbial communities after being amended with plant feedstock and its corresponding biochar. MATERIALS AND METHODS: A soil incubation was conducted for 180 days to monitor the mineralization and evolution of soil-primed C after addition of maize and its biochar pyrolysed at 450 °C. Responses of individual microbial taxa were identified and compared using the next-generation sequencing method. RESULTS AND DISCUSSION: Cumulative CO₂ showed similar trends but different magnitudes in soil supplied with feedstock and its biochar. Feedstock addition resulted in a positive priming effect of 1999 mg C kg⁻¹ soil (+253.7 %) while biochar gave negative primed C of −872.1 mg C kg⁻¹ soil (−254.3 %). Linear relationships between mineralized material and mineralized soil C were detected. Most priming occurred in the first 15 days, indicating co-metabolism. Differences in priming may be explained by differences in properties of plant material, especially the water-extractable organic C. Predominant phyla were affiliated to Acidobacteria, Actinobacteria, Chloroflexi, Gemmatimonadetes, Firmicutes, Planctomycetes, Proteobacteria, Verrucomicrobia, Ascomycota, Basidiomycota, Blastocladiomycota, Chytridiomycota, Zygomycota, Euryarchaeota, and Thaumarchaeota during decomposition. Cluster analysis resulted in separate phylogenetic grouping of feedstock and biochar. Bacteria (Acidobacteria, Firmicutes, Gemmatimonadetes, Planctomycetes), fungi (Ascomycota), and archaea (Euryarchaeota) were closely correlated to primed soil C (R ² = −0.98, −0.99, 0.84, 0.81, 0.91, and 0.91, respectively). CONCLUSIONS: Quality of plant materials (especially labile C) shifted microbial community (specific microbial taxa) responses, resulting in a distinctive priming intensity, giving a better understanding of the functional role of soil microbial community as an important driver of priming effect.