Carbon Inputs from Miscanthus Displace Older Soil Organic Carbon Without Inducing Priming

Andy D. Robertson (Corresponding Author), Christian A. Davies, Andy W. Stott, Pete Smith, Emily L. Clark, Niall P McNamara

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The carbon (C) dynamics of a bioenergy system are key to correctly defining its viability as a sustainable alternative to conventional fossil fuel energy sources. Recent studies have quantified the greenhouse gas mitigation potential of these bioenergy crops, often concluding that C sequestration in soils plays a primary role in offsetting emissions through energy generation. Miscanthus is a particularly promising bioenergy crop and research has shown that soil C stocks can increase by more than 2 t C ha−1 yr−1. In this study, we use a stable isotope (13C) technique to trace the inputs and outputs from soils below a commercial Miscanthus plantation in Lincolnshire, UK, over the first 7 years of growth after conversion from a conventional arable crop. Results suggest that an unchanging total topsoil (0–30 cm) C stock is caused by Miscanthus additions displacing older soil organic matter. Further, using a comparison between bare soil plots (no new Miscanthus inputs) and undisturbed Miscanthus controls, soil respiration was seen to be unaffected through priming by fresh inputs or rhizosphere. The temperature sensitivity of old soil C was also seen to be very similar with and without the presence of live root biomass. Total soil respiration from control plots was dominated by Miscanthus-derived emissions with autotrophic respiration alone accounting for ∼50 % of CO2. Although total soil C stocks did not change significantly over time, the Miscanthus-derived soil C accumulated at a rate of 860 kg C ha−1 yr−1 over the top 30 cm. Ultimately, the results from this study indicate that soil C stocks below Miscanthus plantations do not necessarily increase during the first 7 years.
Original languageEnglish
Pages (from-to)86–101
Number of pages16
JournalBioEnergy Research
Volume10
Issue number1
Early online date22 Jul 2016
DOIs
Publication statusPublished - 1 Mar 2017

Fingerprint

Miscanthus
Organic carbon
soil organic carbon
Soils
Carbon
carbon
soil
energy crops
soil respiration
Crops
plantations
energy
fossil fuels
bioenergy
greenhouse gases
topsoil
stable isotopes
rhizosphere
soil organic matter
carbon dioxide

Keywords

  • Soil C
  • priming
  • bioenergy
  • 13CO2
  • greenhouse gas
  • autotrophic soil respiration

Cite this

Carbon Inputs from Miscanthus Displace Older Soil Organic Carbon Without Inducing Priming. / Robertson, Andy D. (Corresponding Author); Davies, Christian A.; Stott, Andy W.; Smith, Pete; Clark, Emily L.; McNamara, Niall P.

In: BioEnergy Research, Vol. 10, No. 1, 01.03.2017, p. 86–101.

Research output: Contribution to journalArticle

Robertson, Andy D. ; Davies, Christian A. ; Stott, Andy W. ; Smith, Pete ; Clark, Emily L. ; McNamara, Niall P. / Carbon Inputs from Miscanthus Displace Older Soil Organic Carbon Without Inducing Priming. In: BioEnergy Research. 2017 ; Vol. 10, No. 1. pp. 86–101.
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note = "Acknowledgments The authors would like to thank the Centre for Ecology & Hydrology and Shell for providing a joint PhD studentship grant award to Andy Robertson (CEH project number NEC04306). We are also grateful to Sean Case at the University of Copenhagen for help with fieldwork and Helen Grant for help with isotopic analysis. Erratum to: Bioenerg. Res. DOI 10.1007/s12155-016-9772-9 Due to an error in communication between the authors and the publishers the title was not correct and merged with the next line of the manuscript. The title should simply read “Carbon inputs from Miscanthus displace older soil organic carbon without inducing priming”. The original version has been corrected.",
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N1 - Acknowledgments The authors would like to thank the Centre for Ecology & Hydrology and Shell for providing a joint PhD studentship grant award to Andy Robertson (CEH project number NEC04306). We are also grateful to Sean Case at the University of Copenhagen for help with fieldwork and Helen Grant for help with isotopic analysis. Erratum to: Bioenerg. Res. DOI 10.1007/s12155-016-9772-9 Due to an error in communication between the authors and the publishers the title was not correct and merged with the next line of the manuscript. The title should simply read “Carbon inputs from Miscanthus displace older soil organic carbon without inducing priming”. The original version has been corrected.

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N2 - The carbon (C) dynamics of a bioenergy system are key to correctly defining its viability as a sustainable alternative to conventional fossil fuel energy sources. Recent studies have quantified the greenhouse gas mitigation potential of these bioenergy crops, often concluding that C sequestration in soils plays a primary role in offsetting emissions through energy generation. Miscanthus is a particularly promising bioenergy crop and research has shown that soil C stocks can increase by more than 2 t C ha−1 yr−1. In this study, we use a stable isotope (13C) technique to trace the inputs and outputs from soils below a commercial Miscanthus plantation in Lincolnshire, UK, over the first 7 years of growth after conversion from a conventional arable crop. Results suggest that an unchanging total topsoil (0–30 cm) C stock is caused by Miscanthus additions displacing older soil organic matter. Further, using a comparison between bare soil plots (no new Miscanthus inputs) and undisturbed Miscanthus controls, soil respiration was seen to be unaffected through priming by fresh inputs or rhizosphere. The temperature sensitivity of old soil C was also seen to be very similar with and without the presence of live root biomass. Total soil respiration from control plots was dominated by Miscanthus-derived emissions with autotrophic respiration alone accounting for ∼50 % of CO2. Although total soil C stocks did not change significantly over time, the Miscanthus-derived soil C accumulated at a rate of 860 kg C ha−1 yr−1 over the top 30 cm. Ultimately, the results from this study indicate that soil C stocks below Miscanthus plantations do not necessarily increase during the first 7 years.

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