title: Increasing the Size of the Microbial Biomass Altered Bacterial Community Structure which Enhances Plant Phosphorus Uptake.
abstract: Agricultural production can be limited by low phosphorus (P) availability, with soil P being constrained by sorption and precipitation reactions making it less available for plant uptake. There are strong links between carbon (C) and nitrogen (N) availability and P cycling within soil P pools, with microorganisms being an integral component of soil P cycling mediating the availability of P to plants. Here we tested a conceptual model that proposes (i) the addition of readily-available organic substrates would increase the size of the microbial biomass thus exhausting the pool of easily-available P and (ii) this would cause the microbial biomass to access P from more recalcitrant pools. In this model it is hypothesised that the size of the microbial population is regulating access to less available P rather than the diversity of organisms contained within this biomass. To test this hypothesis we added mixtures of simple organic compounds that reflect typical root exudates at different C:N ratios to a soil microcosm experiment and assessed changes in soil P pools, microbial biomass and bacterial diversity measures. We report that low C:N ratio (C:N = 12.5:1) artificial root exudates increased the size of the microbial biomass while high C:N ratio (C:N = 50:1) artificial root exudates did not result in a similar increase in microbial biomass. Interestingly, addition of the root exudates did not alter bacterial diversity (measured via univariate diversity indices) but did alter bacterial community structure. Where C, N and P supply was sufficient to support plant growth the increase observed in microbial biomass occurred with a concurrent increase in plant yield.
authors.affiliation: Soil Biology and Molecular Ecology Group, School of Earth and Environment, Faculty of Science, The University of Western Australia, Crawley, Perth, Western Australia, Australia.|National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, P. R. China.
authors.forename: Pu
authors.initials: P
authors.lastname: Shen
authors.affiliation: Soil Biology and Molecular Ecology Group, School of Earth and Environment, Faculty of Science, The University of Western Australia, Crawley, Perth, Western Australia, Australia.
authors.forename: Daniel Vaughan
authors.initials: DV
authors.lastname: Murphy
authors.affiliation: Soil Biology and Molecular Ecology Group, School of Earth and Environment, Faculty of Science, The University of Western Australia, Crawley, Perth, Western Australia, Australia.
authors.forename: Suman J
authors.initials: SJ
authors.lastname: George
authors.affiliation: Soil Biology and Molecular Ecology Group, School of Earth and Environment, Faculty of Science, The University of Western Australia, Crawley, Perth, Western Australia, Australia.
authors.forename: Hazel
authors.initials: H
authors.lastname: Lapis-Gaza
authors.affiliation: National Engineering Laboratory for Improving Quality of Arable Land, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, P. R. China.
authors.forename: Minggang
authors.initials: M
authors.lastname: Xu
authors.affiliation: Soil Biology and Molecular Ecology Group, School of Earth and Environment, Faculty of Science, The University of Western Australia, Crawley, Perth, Western Australia, Australia.
authors.forename: Deirdre Bridget
authors.identifier: http://orcid.org/0000-0002-9069-7723
authors.initials: DB
authors.lastname: Gleeson
mesh_terms: D001419:Bacteria / Q000235:genetics*; D018533:Biomass; D002244:Carbon / Q000032:analysis / Q000378:metabolism; D008129:Lolium / Q000378:metabolism* / Q000382:microbiology*; D059013:Microbial Consortia / Q000235:genetics / Q000502:physiology; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D010758:Phosphorus / Q000378:metabolism* / Q000493:pharmacokinetics; D012336:RNA, Ribosomal, 16S; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology
chemical_list: D012336:RNA, Ribosomal, 16S; D012987:Soil; D010758:Phosphorus; D002244:Carbon; D009584:Nitrogen