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| Titel |
Using an input manipulation experiment to partition greenhouse gas fluxes from a commercial Miscanthus plantation in the UK |
| VerfasserIn |
Andy Robertson, Christian Davies, Pete Smith, Niall McNamara |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100040
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| Publikation (Nr.) |
 EGU/EGU2014-15918.pdf |
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| Zusammenfassung |
| Miscanthus is a lignocellulosic C4 crop that can be grown for a number of practical end-uses
but recently interest has increased in its viability as a bioenergy crop; both providing a
renewable source of energy and helping to limit climate change by reducing carbon (C)
emissions associated with energy generation. Recent studies have shown that Miscanthus
plantations may increase stocks of soil organic carbon (SOC) however there is still
considerable uncertainty surrounding estimates of net C exchange and the best management
practices to achieve the best greenhouse gas (GHG) mitigation potential. Using an input
manipulation experiment, we monitored emissions of N2O, CH4 and CO2 from living
Miscanthus roots, aboveground plant litter and soil individually to quantify and partition
these emissions and better understand the influence of abiotic factors on SOC and GHG
dynamics under Miscanthus.
In January 2009 twenty-five 2 m2 plots were set up in a three-year old 11 hectare
commercial Miscanthus plantation in Lincolnshire, UK; with five replicates of five
treatments. These treatments varied plant input (roots or senesced aboveground plant litter) to
the soil by way of controlled exclusion techniques. The delta 13C value of soil C and
CO2 emitted from each treatment was measured monthly between March 2009 and
March 2013. Measurements of CH4 and N2O emissions were also taken at the
soil surface from each treatment. Miscanthus-derived emissions were determined
using the isotopic discrimination between C4 plant matter and C3 soil, and the
treatments were compared to assess their effects on C inputs and outputs to the
soil.
Both CH4 and N2O emissions were below detection limits, mainly due to a lack of
fertiliser additions and limited disturbance of the agricultural site. However, results for CO2
emissions indicate a strong seasonal variation; litter decomposition forms a large portion of
the CO2 emissions in winter and spring whereas root respiration dominates the summer and
autumn fluxes. After four years of aboveground plant litter removal there was no
significant change in total soil C stocks indicating that earlier harvests and more
thorough litter removal from the site would have little impact on C inputs to the
soil.
Outside the input manipulation treatments we also compared the top 30cm of soil from
beneath the Miscanthus plantation with that below an adjacent arable field cropped with a
winter wheat and oil seed rape rotation (the prior land use of the Miscanthus site). Results
showed a greater soil C stock in the Miscanthus soils, although the difference was
not statistically significant after 7 years of growth. Additionally, physiochemical
soil fractionation of the top 30cm of soils below the input manipulation treatments
indicates that soil fractions describing particulate organic matter, sand and soil
aggregates all contain significantly more Miscanthus C in the top 15cm than in
the 15-30cm layer, and when both roots and aboveground plant litter are present. |
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