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Title: Differential effects of warming and nitrogen fertilization on soil respiration and microbial dynamics in switchgrass croplands

The mechanistic understanding of warming and nitrogen (N) fertilization, alone or in combination, on microbially mediated decomposition is limited. Here, soil samples were collected from previously harvested switchgrass ( Panicum virgatum L.) plots that had been treated with high N fertilizer (HN: 67 kg N ha -1) and those that had received no N fertilizer (NN) over a 3-year period. The samples were incubated for 180 days at 15°C and 20°C, during which heterotrophic respiration, δ 13C of CO 2, microbial biomass (MB), specific soil respiration rate (R s: respiration per unit of microbial biomass), and exoenzyme activities were quantified at 10 different collections time. Employing switchgrass tissues (referred to as litter) with naturally abundant 13C allowed us to partition CO 2 respiration derived from soil and amended litter. Cumulative soil respiration increased significantly by 16.4% and 4.2% under warming and N fertilization, respectively. Respiration derived from soil was elevated significantly with warming, while oxidase, the agent for recalcitrant soil substrate decomposition, was not significantly affected by warming. Warming, however, significantly enhanced MB and R s indicating a decrease in microbial growth efficiency (MGE). On the contrary, respiration derived from amended litter was elevated with N fertilization, which was consistentmore » with the significantly elevated hydrolase. N fertilization, however, had little effect on MB and Rs, suggesting little change in microbial physiology. Temperature and N fertilization showed minimal interactive effects likely due to little differences in soil N availability between NN and HN samples, which is partly attributable to switchgrass biomass N accumulation (equivalent to ~53% of fertilizer N). Overall, the differential individual effects of warming and N fertilization may be driven by physiological adaptation and stimulated exoenzyme kinetics, respectively. The study shed insights on distinct microbial acquisition of different substrates under global temperature increase and N enrichment.« less
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [2] ; ORCiD logo [3] ; ORCiD logo [3] ; ORCiD logo [4]
  1. Tennessee State Univ., Nashville, TN (United States). Dept. of Agriculture and Environmental Sciences
  2. Univ. of North Carolina, Wilmington, NC (United States). Dept. of Earth and Ocean Sciences
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Climate Change Science Inst. and Environmental Sciences Division
  4. Tennessee State Univ., Nashville, TN (United States). Dept. of Biological Science
Publication Date:
Grant/Contract Number:
AC05-00OR22725; 1005761
Type:
Published Article
Journal Name:
Global Change Biology. Bioenergy
Additional Journal Information:
Journal Volume: 10; Journal Issue: 8; Journal ID: ISSN 1757-1693
Publisher:
Wiley
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23). Climate and Environmental Sciences Division; USDA
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; exoenzyme activities; heterotrophic respiration; microbial biomass; microbial growth efficiency; nitrogen fertilization; soil warming; switchgrass
OSTI Identifier:
1434218
Alternate Identifier(s):
OSTI ID: 1434219; OSTI ID: 1476396

Li, Jianwei, Jian, Siyang, de Koff, Jason P., Lane, Chad S., Wang, Gangsheng, Mayes, Melanie A., and Hui, Dafeng. Differential effects of warming and nitrogen fertilization on soil respiration and microbial dynamics in switchgrass croplands. United States: N. p., Web. doi:10.1111/gcbb.12515.
Li, Jianwei, Jian, Siyang, de Koff, Jason P., Lane, Chad S., Wang, Gangsheng, Mayes, Melanie A., & Hui, Dafeng. Differential effects of warming and nitrogen fertilization on soil respiration and microbial dynamics in switchgrass croplands. United States. doi:10.1111/gcbb.12515.
Li, Jianwei, Jian, Siyang, de Koff, Jason P., Lane, Chad S., Wang, Gangsheng, Mayes, Melanie A., and Hui, Dafeng. 2018. "Differential effects of warming and nitrogen fertilization on soil respiration and microbial dynamics in switchgrass croplands". United States. doi:10.1111/gcbb.12515.
@article{osti_1434218,
title = {Differential effects of warming and nitrogen fertilization on soil respiration and microbial dynamics in switchgrass croplands},
author = {Li, Jianwei and Jian, Siyang and de Koff, Jason P. and Lane, Chad S. and Wang, Gangsheng and Mayes, Melanie A. and Hui, Dafeng},
abstractNote = {The mechanistic understanding of warming and nitrogen (N) fertilization, alone or in combination, on microbially mediated decomposition is limited. Here, soil samples were collected from previously harvested switchgrass (Panicum virgatum L.) plots that had been treated with high N fertilizer (HN: 67 kg N ha-1) and those that had received no N fertilizer (NN) over a 3-year period. The samples were incubated for 180 days at 15°C and 20°C, during which heterotrophic respiration, δ13C of CO2, microbial biomass (MB), specific soil respiration rate (Rs: respiration per unit of microbial biomass), and exoenzyme activities were quantified at 10 different collections time. Employing switchgrass tissues (referred to as litter) with naturally abundant 13C allowed us to partition CO2 respiration derived from soil and amended litter. Cumulative soil respiration increased significantly by 16.4% and 4.2% under warming and N fertilization, respectively. Respiration derived from soil was elevated significantly with warming, while oxidase, the agent for recalcitrant soil substrate decomposition, was not significantly affected by warming. Warming, however, significantly enhanced MB and Rs indicating a decrease in microbial growth efficiency (MGE). On the contrary, respiration derived from amended litter was elevated with N fertilization, which was consistent with the significantly elevated hydrolase. N fertilization, however, had little effect on MB and Rs, suggesting little change in microbial physiology. Temperature and N fertilization showed minimal interactive effects likely due to little differences in soil N availability between NN and HN samples, which is partly attributable to switchgrass biomass N accumulation (equivalent to ~53% of fertilizer N). Overall, the differential individual effects of warming and N fertilization may be driven by physiological adaptation and stimulated exoenzyme kinetics, respectively. The study shed insights on distinct microbial acquisition of different substrates under global temperature increase and N enrichment.},
doi = {10.1111/gcbb.12515},
journal = {Global Change Biology. Bioenergy},
number = 8,
volume = 10,
place = {United States},
year = {2018},
month = {4}
}