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Root exudates with low C/N ratios accelerate CO2 emissions from paddy soil

Cai, Guan ; Shahbaz, Muhammad LU ; Ge, Tida ; Hu, Yajun ; Li, Baozhen ; Yuan, Hongzhao ; Wang, Yi ; Liu, Yuhuai ; Liu, Qiong and Shibistova, Olga , et al. (2022) In Land Degradation and Development 33(8). p.1193-1203
Abstract
Root exudates can significantly modify microbial activity and soil organic matter (SOM) mineralization. However, how root exudates and their C/N stoichiometric ratios control paddy soil C mineralization is poorly understood. This study used a mixture of glucose, oxalic acid, and alanine as root exudate mimics for three C/N stoichiometric ratios (CN6, CN10, and CN80) to explore the underlying mechanisms involved in SOM mineralization. The input of root exudates enhanced CO2 emissions by 1.8–2.3-fold that of soil with only C additions (C-only). Artificial root exudates with low C/N ratios (CN6 and CN10) increased the metabolic quotient (qCO2) by 12% over those with higher stoichiometric ratios (CN80 and C-only), suggesting a relatively high... (More)
Root exudates can significantly modify microbial activity and soil organic matter (SOM) mineralization. However, how root exudates and their C/N stoichiometric ratios control paddy soil C mineralization is poorly understood. This study used a mixture of glucose, oxalic acid, and alanine as root exudate mimics for three C/N stoichiometric ratios (CN6, CN10, and CN80) to explore the underlying mechanisms involved in SOM mineralization. The input of root exudates enhanced CO2 emissions by 1.8–2.3-fold that of soil with only C additions (C-only). Artificial root exudates with low C/N ratios (CN6 and CN10) increased the metabolic quotient (qCO2) by 12% over those with higher stoichiometric ratios (CN80 and C-only), suggesting a relatively high energy demand for microorganisms to acquire organic N from SOM by increasing N-hydrolase production. The increase of stoichiometric ratios of C- to N-hydrolase (β-1,4-glucosidase to β-1,4-N-acetyl glucosaminidase) promoted SOM degradation compared to those involved in organic C- and N- degradation, which had a significant positive correlation with qCO2. The stoichiometric ratios of microbial biomass (MBC/MBN) were positively correlated with C use efficiency, indicating root exudates with higher C/N ratios provide an undersupply of N for microorganisms that trigger the release of N-degrading extracellular enzymes. Our findings showed that the C/N stoichiometry of root exudates controlled SOM mineralization by affecting the specific response of the microbial biomass through the activity of C- and N-releasing extracellular enzymes to adjust the microbial C/N ratio. (Less)
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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Land Degradation and Development
volume
33
issue
8
pages
1193 - 1203
publisher
John Wiley & Sons Inc.
external identifiers
  • scopus:85127414234
ISSN
1099-145X
DOI
10.1002/ldr.4198
language
English
LU publication?
yes
id
09a25eba-e5f1-41f8-9bf3-952390f03396
date added to LUP
2022-01-13 12:54:26
date last changed
2022-06-07 14:05:30
@article{09a25eba-e5f1-41f8-9bf3-952390f03396,
  abstract     = {{Root exudates can significantly modify microbial activity and soil organic matter (SOM) mineralization. However, how root exudates and their C/N stoichiometric ratios control paddy soil C mineralization is poorly understood. This study used a mixture of glucose, oxalic acid, and alanine as root exudate mimics for three C/N stoichiometric ratios (CN6, CN10, and CN80) to explore the underlying mechanisms involved in SOM mineralization. The input of root exudates enhanced CO2 emissions by 1.8–2.3-fold that of soil with only C additions (C-only). Artificial root exudates with low C/N ratios (CN6 and CN10) increased the metabolic quotient (qCO2) by 12% over those with higher stoichiometric ratios (CN80 and C-only), suggesting a relatively high energy demand for microorganisms to acquire organic N from SOM by increasing N-hydrolase production. The increase of stoichiometric ratios of C- to N-hydrolase (β-1,4-glucosidase to β-1,4-N-acetyl glucosaminidase) promoted SOM degradation compared to those involved in organic C- and N- degradation, which had a significant positive correlation with qCO2. The stoichiometric ratios of microbial biomass (MBC/MBN) were positively correlated with C use efficiency, indicating root exudates with higher C/N ratios provide an undersupply of N for microorganisms that trigger the release of N-degrading extracellular enzymes. Our findings showed that the C/N stoichiometry of root exudates controlled SOM mineralization by affecting the specific response of the microbial biomass through the activity of C- and N-releasing extracellular enzymes to adjust the microbial C/N ratio.}},
  author       = {{Cai, Guan and Shahbaz, Muhammad and Ge, Tida and Hu, Yajun and Li, Baozhen and Yuan, Hongzhao and Wang, Yi and Liu, Yuhuai and Liu, Qiong and Shibistova, Olga and Sauheitl, Leopold and Wu, Jinshui and Guggenberger, Georg and Zhu, Zhenke}},
  issn         = {{1099-145X}},
  language     = {{eng}},
  number       = {{8}},
  pages        = {{1193--1203}},
  publisher    = {{John Wiley & Sons Inc.}},
  series       = {{Land Degradation and Development}},
  title        = {{Root exudates with low C/N ratios accelerate CO2 emissions from paddy soil}},
  url          = {{http://dx.doi.org/10.1002/ldr.4198}},
  doi          = {{10.1002/ldr.4198}},
  volume       = {{33}},
  year         = {{2022}},
}