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Abundance, production and stabilization of microbial biomass under conventional and reduced tillage

van Groenigen, Kees-Jan; Bloem, Jaap; Bååth, Erland LU ; Boeckx, Pascal; Rousk, Johannes LU ; Bode, Samuel; Forristal, Dermot and Jones, Michael B. (2010) In Soil Biology & Biochemistry 42(1). p.48-55
Abstract
Soil tillage practices affect the soil microbial community in various ways, with possible consequences for nitrogen (N) losses, plant growth and soil organic carbon (C) sequestration. As microbes affect soil organic matter (SOM) dynamics largely through their activity, their impact may not be deduced from biomass measurements alone. Moreover, residual microbial tissue is thought to facilitate SOM stabilization, and to provide a long term integrated measure of effects on the microorganisms. In this study, we therefore compared the effect of reduced (RT) and conventional tillage (CT) on the biomass, growth rate. and residues of the major microbial decomposer groups fungi and bacteria. Soil samples were collected at two depths (0-5 cm and... (More)
Soil tillage practices affect the soil microbial community in various ways, with possible consequences for nitrogen (N) losses, plant growth and soil organic carbon (C) sequestration. As microbes affect soil organic matter (SOM) dynamics largely through their activity, their impact may not be deduced from biomass measurements alone. Moreover, residual microbial tissue is thought to facilitate SOM stabilization, and to provide a long term integrated measure of effects on the microorganisms. In this study, we therefore compared the effect of reduced (RT) and conventional tillage (CT) on the biomass, growth rate. and residues of the major microbial decomposer groups fungi and bacteria. Soil samples were collected at two depths (0-5 cm and 5-20 cm) from plots in an Irish winter wheat field that were exposed to either conventional or shallow non-inversion tillage for 7 growing seasons. Total soil fungal and bacterial biomasses were estimated using epifluorescence microscopy. To separate between biomass of saprophytic fungi and arbuscular mycorrhizae, samples were analyzed for ergosterol and phospholipid fatty acid (PLFA) biomarkers. Growth rates of saprophytic fungi were determined by [C-14]acetate-in-ergosterol incorporation, whereas bacterial growth rates were determined by the incorporation of H-3-leucine in bacterial proteins. Finally, soil contents of fungal and bacterial residues were estimated by quantifying microbial derived amino sugars. Reduced tillage increased the total biomass of both bacteria and fungi in the 0-5 cm soil layer to a similar extent. Both ergosterol and PLFA analyses indicated that RT increased biomass of saprophytic fungi in the 0-5 cm soil layer. In contrast, RT increased the biomass of arbuscular mycorrhizae as well as its contribution to the total fungal biomass across the whole plough layer. Growth rates of both saprotrophic fungi and bacteria on the other hand were not affected by soil tillage, possibly indicating a decreased turnover rate of soil microbial biomass under RT. Moreover, RT did not affect the proportion of microbial residues that were derived from fungi. In summary, our results suggest that RT can promote soil C storage without increasing the role of saprophytic fungi in SOM dynamics relative to that of bacteria. (C) 2009 Elsevier Ltd. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
residues, Microbial, Microbial growth, Bacteria, Fungi, Tillage, Mycorrhizae
in
Soil Biology & Biochemistry
volume
42
issue
1
pages
48 - 55
publisher
Elsevier
external identifiers
  • wos:000272858300006
  • scopus:70449525145
ISSN
0038-0717
DOI
10.1016/j.soilbio.2009.09.023
project
Effect of environmental factors on fungal and bacterial growth in soil
BECC
language
English
LU publication?
yes
id
b1815833-8b1e-4b5e-a721-d029181120c0 (old id 1535561)
date added to LUP
2010-01-25 15:44:44
date last changed
2018-07-15 03:49:19
@article{b1815833-8b1e-4b5e-a721-d029181120c0,
  abstract     = {Soil tillage practices affect the soil microbial community in various ways, with possible consequences for nitrogen (N) losses, plant growth and soil organic carbon (C) sequestration. As microbes affect soil organic matter (SOM) dynamics largely through their activity, their impact may not be deduced from biomass measurements alone. Moreover, residual microbial tissue is thought to facilitate SOM stabilization, and to provide a long term integrated measure of effects on the microorganisms. In this study, we therefore compared the effect of reduced (RT) and conventional tillage (CT) on the biomass, growth rate. and residues of the major microbial decomposer groups fungi and bacteria. Soil samples were collected at two depths (0-5 cm and 5-20 cm) from plots in an Irish winter wheat field that were exposed to either conventional or shallow non-inversion tillage for 7 growing seasons. Total soil fungal and bacterial biomasses were estimated using epifluorescence microscopy. To separate between biomass of saprophytic fungi and arbuscular mycorrhizae, samples were analyzed for ergosterol and phospholipid fatty acid (PLFA) biomarkers. Growth rates of saprophytic fungi were determined by [C-14]acetate-in-ergosterol incorporation, whereas bacterial growth rates were determined by the incorporation of H-3-leucine in bacterial proteins. Finally, soil contents of fungal and bacterial residues were estimated by quantifying microbial derived amino sugars. Reduced tillage increased the total biomass of both bacteria and fungi in the 0-5 cm soil layer to a similar extent. Both ergosterol and PLFA analyses indicated that RT increased biomass of saprophytic fungi in the 0-5 cm soil layer. In contrast, RT increased the biomass of arbuscular mycorrhizae as well as its contribution to the total fungal biomass across the whole plough layer. Growth rates of both saprotrophic fungi and bacteria on the other hand were not affected by soil tillage, possibly indicating a decreased turnover rate of soil microbial biomass under RT. Moreover, RT did not affect the proportion of microbial residues that were derived from fungi. In summary, our results suggest that RT can promote soil C storage without increasing the role of saprophytic fungi in SOM dynamics relative to that of bacteria. (C) 2009 Elsevier Ltd. All rights reserved.},
  author       = {van Groenigen, Kees-Jan and Bloem, Jaap and Bååth, Erland and Boeckx, Pascal and Rousk, Johannes and Bode, Samuel and Forristal, Dermot and Jones, Michael B.},
  issn         = {0038-0717},
  keyword      = {residues,Microbial,Microbial growth,Bacteria,Fungi,Tillage,Mycorrhizae},
  language     = {eng},
  number       = {1},
  pages        = {48--55},
  publisher    = {Elsevier},
  series       = {Soil Biology & Biochemistry},
  title        = {Abundance, production and stabilization of microbial biomass under conventional and reduced tillage},
  url          = {http://dx.doi.org/10.1016/j.soilbio.2009.09.023},
  volume       = {42},
  year         = {2010},
}