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| Titel |
Effect of cattle urine addition on the surface emissions and subsurface concentrations of greenhouse gases from a UK lowland peatland. |
| VerfasserIn |
Alex Boon, Steve Robinson, David Chadwick, Laura Cardenas |
| 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 |
250092463
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| Publikation (Nr.) |
 EGU/EGU2014-6811.pdf |
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| Zusammenfassung |
| Grazing systems represent a substantial percentage of the global anthropogenic flux of nitrous
oxide (N2O) as a result of nitrogen addition to the soil. Cattle urine has been shown to
stimulate N2O production due to the dual effect of a large pool of readily available N and C
and increased soil water content. Studies indicate that even short-term grazing can
cause a significant increase in N2O emissions, particularly when combined with
compaction and seasonal water-table rise. Peat soils have different physical and chemical
characteristics to mineral soils including higher organic carbon content, higher porosity and
greater variation in hydraulic properties due to swell and shrink. Peat soils have been
shown to have increased N2O emissions with respect to mineral soils as a result of a
combination of these factors, particularly when amended with fertilisers or livestock
excreta.
Many lowland peatland environments in the UK are under seasonal grazing management
and cattle are increasingly being introduced to manage fen vegetation in lowland
peatland. In this study, we simulated small urination events on a conservation area
of UK peat grassland that is intensively grazed for a short period of time during
autumn seasonal water-table rise. We measured subsurface and surface emissions
of N2O, methane (CH4) and carbon dioxide (CO2) alongside soil physical and
chemical changes to determine the key mechanisms of greenhouse gas production and
transport.
CO2emission peaked at 5200 mg CO2 m-2 d-1 directly after application from a
background value of 905 mg CO2 m-2 d-1. CH4 flux decreased to -2000 μg CH4 m-2
d-1two days after application (control plots -580 μg CH4 m-2 d-1); however, net CH4 flux
was positive from urine treated plots and negative from control plots. N2O emission peaked at
37 mg N2O m-2 d-1 12 days after application (1.08 mg N2O m-2 d-1 in control plots).
Subsurface CH4 and N2O concentrations were higher in the urine treated plots than the
controls. There was no effect of treatment on subsurface CO2 concentrations. Subsurface
N2O peaked at 500ppm 12 days after and 1200ppm 56 days after application. Subsurface
NO3- concentration peaked at approximately 300 mg N kg dry soil-112 days after
application.
Results indicate that denitrification is the key driver for N2O release in peatlands and that
production is strongly related to increased soil moisture. N2O production at depth continued
long after emissions were detected at the surface. Increased study of the interaction
between subsurface gas concentrations, surface emissions and soil hydrological
conditions is required to successfully predict greenhouse gas production and emission. |
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