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Substrate spatial heterogeneity reduces soil microbial activity

Shi, Andong and Chakrawal, Arjun and Manzoni, Stefano and Fischer, Benjamin M.C. and Nunan, Naoise and Herrmann, Anke (2021). Substrate spatial heterogeneity reduces soil microbial activity. Soil Biology and Biochemistry. 152 , 108068
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Abstract

Soil heterogeneity influences microbial access to substrates and creates habitats varying in substrate concentrations, thus leading to local variations in carbon (C) dynamics. Based on theoretical considerations, we expected that higher heterogeneity would decrease microbial activity. To test this hypothesis, we modified substrate spatial heterogeneity using 3D-printed cylinders with four compartments (either preventing or allowing diffusion between compartments). The same total amount of glucose (1.5 mg glucose C per cylinder) was added either to one compartment (highest local concentration, 2.0 mg glucose C g−1 soil, and highest heterogeneity), to two (medium concentration, 1.0 mg glucose C g−1 soil, and intermediate heterogeneity), or to four compartments (lowest local concentration, 0.5 mg glucose C g−1 soil, and equivalent to homogeneous conditions). Thus, we experimentally created a gradient of substrate spatial heterogeneity. The 3D cylinders containing soil were transferred into standard calorimetry ampoules and were incubated in isothermal calorimeters to monitor soil heat dissipation rates as a proxy of soil microbial activity over 51 h at 18 °C. When diffusion among compartments was prevented, the most heterogeneous treatment showed the lowest heat dissipation rates, despite having the highest local substrate concentration. Compared to homogeneous conditions, the heat dissipation rate from the most heterogeneous treatment was 110% lower at the beginning of the experiment (12.7 μJ g−1 soil s−1) and 50% lower when heat dissipation rates reached a peak (72.6 μJ g−1 soil s−1). Moreover, the peak was delayed by approximately 2 h compared to the most homogeneous treatment. When diffusion among compartments was allowed, the effect of substrate spatial heterogeneity on microbial activity was strongly diminished. Our findings emphasize the influence of substrate spatial heterogeneity on soil microbial dynamics, highlighting the importance of including it in C cycling models for a better understanding of soil C dynamics.

Authors/Creators:Shi, Andong and Chakrawal, Arjun and Manzoni, Stefano and Fischer, Benjamin M.C. and Nunan, Naoise and Herrmann, Anke
Title:Substrate spatial heterogeneity reduces soil microbial activity
Series Name/Journal:Soil Biology and Biochemistry
Year of publishing :2021
Volume:152
Article number:108068
Number of Pages:9
ISSN:0038-0717
Language:English
Publication Type:Journal article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science
Keywords:Carbon cycling models, Diffusion, Heat dissipation, Scale transition theory, Spatial heterogeneity, Spatial homogeneity
URN:NBN:urn:nbn:se:slu:epsilon-p-108941
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-108941
Additional ID:
Type of IDID
DOI10.1016/j.soilbio.2020.108068
ID Code:19067
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Soil and Environment
(S) > Dept. of Soil and Environment
Deposited By: SLUpub Connector
Deposited On:01 Dec 2020 08:43
Metadata Last Modified:01 Dec 2020 08:51

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