The second generation bioenergy crops Miscanthus x giganteus and short rotation coppice (SRC) willow are the two main bioenergy crops in the UK and have become an integral part of legislation to provide an alternative to fossil fuels and to reduce national greenhouse gas (GHG) emissions. To reach emission targets, it is estimated that approximately 350,000 ha of land could be made available for bioenergy crops by 2020. Despite the promise of these crops, there have been very few field-studies regarding soil GHG (CO2, CH4 and N2O) emissions and many of the published studies are life cycle analyses or modelled fluxes from soils using default values from the IPCC. The first aim of this research was to quantify the in situ soil GHG budget and to establish the drivers of these GHG fluxes for Miscanthus and SRC willow. The second aim of this research was to provide a more in-depth understanding of C cycling under Miscanthus i.e. litter and roots through two field experiments. Overall, the results from this work confirm minimal emissions of CH4 and N2O from soil under Miscanthus and SRC willow. CO2 flux was found to be the major efflux from soils and it was found in Miscanthus, that the majority of this flux was derived from below ground respiration. Litter played an important part in providing nutrients to the soil, which is vital in systems that are not fertilised. Litter also contributed to SOM accumulation on the soil surface and may promote long-term C sequestration. The results from this work combined with other literature would suggest that these second generation crops offer advantages to first generation crops, but more field-based studies are required to say if they can offer the large-scale GHG savings needed to be a viable alternative to fossil fuels.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:571689 |
| Date | January 2012 |
| Creators | Bottoms, Emily L. |
| Publisher | University of Aberdeen |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=194783 |
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