Impact of Cropping Systems, Soil Inoculum, and Plant Species Identity on Soil Bacterial Community Structure.
Farming practices affect the soil microbial community, which in turn impacts crop growth and crop-weed interactions. This study assessed the modification of soil bacterial community structure by organic or conventional cropping systems, weed species identity [Amaranthus retroflexus L. (redroot pigweed) or Avena fatua L. (wild oat)], and living or sterilized inoculum. Soil from eight paired USDA-certified organic and conventional farms in north-central Montana was used as living or autoclave-sterilized inoculant into steam-pasteurized potting soil, planted with Am. retroflexus or Av. fatua and grown for two consecutive 8-week periods to condition soil nutrients and biota. Subsequently, the V3-V4 regions of the microbial 16S rRNA gene were sequenced by Illumina MiSeq. Treatments clustered significantly, with living or sterilized inoculum being the strongest delineating factor, followed by organic or conventional cropping system, then individual farm. Living inoculum-treated soil had greater species richness and was more diverse than sterile inoculum-treated soil (observed OTUs, Chao, inverse Simpson, Shannon, P < 0.001) and had more discriminant taxa delineating groups (linear discriminant analysis). Living inoculum soil contained more Chloroflexi and Acidobacteria, while the sterile inoculum soil had more Bacteroidetes, Firmicutes, Gemmatimonadetes, and Verrucomicrobia. Organically farmed inoculum-treated soil had greater species richness, more diversity (observed OTUs, Chao, Shannon, P < 0.05), and more discriminant taxa than conventionally farmed inoculum-treated soil. Cyanobacteria were higher in pots growing Am. retroflexus, regardless of inoculum type, for three of the four organic farms. Results highlight the potential of cropping systems and species identity to modify soil bacterial communities, subsequently modifying plant growth and crop-weed competition.
Department of Animal and Range Sciences, Montana State University, P.O. Box 172900, Bozeman, MT, 59717, USA.|Department of Land Resources and Environmental Sciences, Montana State University, P.O. Box 173120, Bozeman, MT, 59717, USA.
Suzanne L
SL
Ishaq
Department of Land Resources and Environmental Sciences, Montana State University, P.O. Box 173120, Bozeman, MT, 59717, USA.
Stephen P
SP
Johnson
Western Agriculture Research Center, Montana State University, Bozeman, MT, USA.
Zach J
ZJ
Miller
Department of Entomology, Plant Pathology and Weed Science, New Mexico State University, Las Cruces, NM, USA.
Erik A
EA
Lehnhoff
Department of Animal and Range Sciences, Montana State University, P.O. Box 172900, Bozeman, MT, 59717, USA.
Sarah
S
Olivo
Department of Animal and Range Sciences, Montana State University, P.O. Box 172900, Bozeman, MT, 59717, USA. carl.yeoman@montana.edu.
Carl J
CJ
Yeoman
Department of Land Resources and Environmental Sciences, Montana State University, P.O. Box 173120, Bozeman, MT, 59717, USA. menalled@montana.edu.
Fabian D
FD
Menalled
D000383:Agriculture; D018554:Avena; D001419:Bacteria / Q000145:classification* / Q000235:genetics; D001483:Base Sequence; D044822:Biodiversity; D058448:Biota; D002965:Classification; D018556:Crops, Agricultural / Q000382:microbiology*; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D005798:Genes, Bacterial; D056186:Metagenomics; D059013:Microbial Consortia; D009009:Montana; D009586:Nitrogen Fixation; D010802:Phylogeny; D063245:Plant Development; D057685:Plant Weeds; D010944:Plants / Q000145:classification / Q000382:microbiology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012987:Soil / Q000737:chemistry*; D012988:Soil Microbiology
D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S; D012987:Soil
16S rRNA; Amaranthus retroflexus; Avena fatua; Conventional farming; Illumina MiSeq; Organic farming; Soil microbial diversity
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