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Abstract
To date, most Miscanthus trials and commercial fields have been planted on arable land. Energy crops will need to be grown more on lower grade lands unsuitable for arable crops. Semi-improved grasslands represent a major land resource for energy crops. In such grasslands, where soil organic carbon (SOC) levels can be high, there have been concerns that the carbon mitigation benefits of bioenergy from Miscanthus could be offset by losses in SOC associated with land use change. At a site in Wales (UK), we quantified the relatively short-term impacts (6 years) of four novel Miscanthushybrids andMiscanthus9giganteuson SOC in improved grassland. After 6 years, using stable carbon isotope ratios ( 13C/12C), the amount of Miscanthus derived C (C4) in total SOC was considerable (ca. 12%) and positively correlated to belowground biomass of different hybrids. Nevertheless, sig-nificant changes in SOC stocks (0–30 cm) were not detected as C4 Miscanthuscarbon replaced the initial C3 grassland carbon; however, initial SOC decreased more in the presence of higher belowground biomass. We ascribed this apparently contradictory result to the rhizosphere priming effect triggered by easily available C sources. Observed changes in SOC partitioning were modelled using the RothC soil carbon turnover model and projected for 20 years showing that there is no significant change in SOC throughout the anticipated life of a Miscanthus crop. We interpret our observations to mean that the new labile C from Miscanthushas replaced the labile C from the grassland and, therefore, planting Miscanthus causes an insignificant change in soil organic car-bon. The overall C mitigation benefit is therefore not decreased by depletion of soil C and is due to substitution of fossil fuel by the aboveground biomass, in this instance 73–108 Mg C ha-1 for the lowest and highest yielding hybrids, respectively, after 6 years.
Original language | English |
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Pages (from-to) | 360-370 |
Number of pages | 11 |
Journal | GCB Bioenergy |
Volume | 6 |
Issue number | 4 |
Early online date | 12 Apr 2013 |
DOIs | |
Publication status | Published - Jul 2013 |
Keywords
- Bioenergy
- Grassland
- Miscanthus
- Priming effect
- roots
- SOC
- stable carbon isotope
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- 4 Finished
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Integrative bioinformatics platform, data integration and modelling
Donnison, I. (PI), Boyle, R. (PI), Clare, A. (PI), Hardy, N. (PI), Huang, L. (PI) & Neal, M. (PI)
01 Apr 2012 → 01 Apr 2017
Project: Externally funded research
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Optimising and sustaining biomass yield
Donnison, I. (PI), Farrar, K. (PI) & Slavov, G. (PI)
01 Apr 2012 → 31 Mar 2017
Project: Externally funded research
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Understanding processes determining soil carbon balances under perennial bioenergy crops CARBO-BIOCROP
Donnison, I. (PI)
Natural Environment Research Council
01 Jun 2010 → 31 Dec 2014
Project: Externally funded research
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Molecular Genetics of Miscanthus
Donnison, I. (PI) & Clifton-Brown, J. (PI)
Biotechnology and Biological Sciences Research Council
01 Apr 2008 → 31 Mar 2012
Project: Externally funded research