title: Phylogenetic and functional potential links pH and N2O emissions in pasture soils.
abstract: Denitrification is mediated by microbial, and physicochemical, processes leading to nitrogen loss via N2O and N2emissions. Soil pH regulates the reduction of N2O to N2, however, it can also affect microbial community composition and functional potential. Here we simultaneously test the link between pH, community composition, and the N2O emission ratio (N2O/(NO + N2O + N2)) in 13 temperate pasture soils. Physicochemical analysis, gas kinetics, 16S rRNA amplicon sequencing, metagenomic and quantitative PCR (of denitrifier genes: nirS, nirK, nosZI and nosZII) analysis were carried out to characterize each soil. We found strong evidence linking pH to both N2O emission ratio and community changes. Soil pH was negatively associated with N2O emission ratio, while being positively associated with both community diversity and total denitrification gene (nir &nos) abundance. Abundance of nosZII was positively linked to pH, and negatively linked to N2O emissions. Our results confirm that pH imposes a general selective pressure on the entire community and that this results in changes in emission potential. Our data also support the general model that with increased microbial diversity efficiency increases, demonstrated in this study with lowered N2O emission ratio through more efficient conversion of N2O to N2.
authors: Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.
authors: Md Sainur
authors: MS
authors: Samad
authors: Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.
authors: Ambarish
authors: A
authors: Biswas
authors: Department of Environmental Sciences, Norwegian University of Life Sciences, Ås, Norway.
authors: Lars R
authors: LR
authors: Bakken
authors: Department of Soil and Physical Sciences, Lincoln University, Lincoln, New Zealand.
authors: Timothy J
authors: TJ
authors: Clough
authors: AgResearch Invermay, Mosgiel, New Zealand.
authors: Cecile A M
authors: CA
authors: de Klein
authors: Teagasc, Environmental Research Centre, Johnstown Castle, Wexford, Ireland.
authors: Karl G
authors: KG
authors: Richards
authors: Teagasc, Environmental Research Centre, Johnstown Castle, Wexford, Ireland.
authors: Gary J
authors: GJ
authors: Lanigan
authors: Department of Microbiology and Immunology, Otago School of Medical Sciences, University of Otago, Dunedin, New Zealand.
authors: Sergio E
authors: SE
authors: Morales
mesh_terms: D000383:Agriculture; D044822:Biodiversity; D058440:Denitrification / Q000235:genetics; D064351:Genes, Microbial; D000074382:Greenhouse Gases / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D054892:Metagenome; D059013:Microbial Consortia / Q000235:genetics; D009584:Nitrogen / Q000032:analysis; D009609:Nitrous Oxide / Q000032:analysis; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000032:analysis / Q000235:genetics; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
chemical_list: D000074382:Greenhouse Gases; D012336:RNA, Ribosomal, 16S; D012987:Soil; D009609:Nitrous Oxide; D009584:Nitrogen