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Relative degradability of exogenous organic carbon in function of its concentration and the interaction with native soil organic matter content

Orly Milton Mendoza Aguirre (UGent) , Heleen Deroo (UGent) , Haichao Li (UGent) , Stefaan De Neve (UGent) and Steven Sleutel (UGent)
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Abstract
The soil environment impacts carbon turnover in a multitude of ways. It has been shown that C emissions are higher when exogenous carbon is locally concentrated than when it is spread in the soil matrix. Hence, the spatial separation between decomposers and substrate may cause ineffective dispersion of the produced enzymes within the soil matrix. It is not clear, however, if and how lower doses of exogenous C impact its degradability and if an interaction exists with native soil organic matter (SOM) level. Therefore, a seventy-day incubation experiment with six varying exogenous OM doses (0-6 g C kg-1) in soil mesocosms of loamy sand subsoil (WFPS 50%) with three different native SOM contents (i.e. 0.1, 0.5, and 1.0 %) was carried out. C emission and isotopic signature measurements of 13CO2 by means of a CRDS-analyser were used to track the degradation of added maize shoots with a δ13C=-12.7‰ that contrasts to native SOM (δ13C=-25‰). Mineral N was added, and the redox potential (Eh) monitored. Eh suggested that O2 may have not become limiting for C mineralisation, even at higher doses, but it did not clearly relate to the added C dose. Cumulative CO2 emissions increased proportionally with C dose and so our hypothesis that a lower dose dispersion limits microbial activity was disproved. However, a higher native SOM level led to higher relative degradability of added C for the highest doses (i.e. 3 and 6 g kg-1 soil). Furthermore, a negative impact of OM doses above 1 g kg-1 soil on native SOM degradation was found. We conclude that positive priming of native SOM mineralisation did not occur. A disproportional response of microbial biomass carbon and soil C mineralisation at lower doses suggests that dose does impact the microbial metabolic quotient. Ongoing PLFA analyses will help us interpret these observations.

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MLA
Mendoza Aguirre, Orly Milton, et al. “Relative Degradability of Exogenous Organic Carbon in Function of Its Concentration and the Interaction with Native Soil Organic Matter Content.” 24th National Symposium for Applied Biological Sciences (NSABS 2019), Abstracts, 2019.
APA
Mendoza Aguirre, O. M., Deroo, H., Li, H., De Neve, S., & Sleutel, S. (2019). Relative degradability of exogenous organic carbon in function of its concentration and the interaction with native soil organic matter content. 24th National Symposium for Applied Biological Sciences (NSABS 2019), Abstracts. Presented at the 24th National Symposium for Applied Biological Sciences (NSABS 2019), Ghent, Belgium.
Chicago author-date
Mendoza Aguirre, Orly Milton, Heleen Deroo, Haichao Li, Stefaan De Neve, and Steven Sleutel. 2019. “Relative Degradability of Exogenous Organic Carbon in Function of Its Concentration and the Interaction with Native Soil Organic Matter Content.” In 24th National Symposium for Applied Biological Sciences (NSABS 2019), Abstracts.
Chicago author-date (all authors)
Mendoza Aguirre, Orly Milton, Heleen Deroo, Haichao Li, Stefaan De Neve, and Steven Sleutel. 2019. “Relative Degradability of Exogenous Organic Carbon in Function of Its Concentration and the Interaction with Native Soil Organic Matter Content.” In 24th National Symposium for Applied Biological Sciences (NSABS 2019), Abstracts.
Vancouver
1.
Mendoza Aguirre OM, Deroo H, Li H, De Neve S, Sleutel S. Relative degradability of exogenous organic carbon in function of its concentration and the interaction with native soil organic matter content. In: 24th National Symposium for Applied Biological Sciences (NSABS 2019), Abstracts. 2019.
IEEE
[1]
O. M. Mendoza Aguirre, H. Deroo, H. Li, S. De Neve, and S. Sleutel, “Relative degradability of exogenous organic carbon in function of its concentration and the interaction with native soil organic matter content,” in 24th National Symposium for Applied Biological Sciences (NSABS 2019), Abstracts, Ghent, Belgium, 2019.
@inproceedings{8698742,
  abstract     = {{The soil environment impacts carbon turnover in a multitude of ways. It has been shown that C emissions are higher when exogenous carbon is locally concentrated than when it is spread in the soil matrix. Hence, the spatial separation between decomposers and substrate may cause ineffective dispersion of the produced enzymes within the soil matrix. It is not clear, however, if and how lower doses of exogenous C impact its degradability and if an interaction exists with native soil organic matter (SOM) level. Therefore, a seventy-day incubation experiment with six varying exogenous OM doses (0-6 g C kg-1) in soil mesocosms of loamy sand subsoil (WFPS 50%) with three different native SOM contents (i.e. 0.1, 0.5, and 1.0 %) was carried out. C emission and isotopic signature measurements of 13CO2 by means of a CRDS-analyser were used to track the degradation of added maize shoots with a δ13C=-12.7‰ that contrasts to native SOM (δ13C=-25‰). Mineral N was added, and the redox potential (Eh) monitored. Eh suggested that O2 may have not become limiting for C mineralisation, even at higher doses, but it did not clearly relate to the added C dose. Cumulative CO2 emissions increased proportionally with C dose and so our hypothesis that a lower dose dispersion limits microbial activity was disproved. However, a higher native SOM level led to higher relative degradability of added C for the highest doses (i.e. 3 and 6 g kg-1 soil). Furthermore, a negative impact of OM doses above 1 g kg-1 soil on native SOM degradation was found. We conclude that positive priming of native SOM mineralisation did not occur. A disproportional response of microbial biomass carbon and soil C mineralisation at lower doses suggests that dose does impact the microbial metabolic quotient. Ongoing PLFA analyses will help us interpret these observations.}},
  articleno    = {{P14}},
  author       = {{Mendoza Aguirre, Orly Milton and Deroo, Heleen and Li, Haichao and De Neve, Stefaan and Sleutel, Steven}},
  booktitle    = {{24th National Symposium for Applied Biological Sciences (NSABS 2019), Abstracts}},
  language     = {{eng}},
  location     = {{Ghent, Belgium}},
  title        = {{Relative degradability of exogenous organic carbon in function of its concentration and the interaction with native soil organic matter content}},
  url          = {{https://nsabs2019.ugent.be/}},
  year         = {{2019}},
}