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| Titel |
Annual emissions of CH4 and N2O, and ecosystem respiration, from eight organic soils in Western Denmark managed by agriculture |
| VerfasserIn |
S. O. Petersen, C. C. Hoffmann, C.-M. Schäfer, G. Blicher-Mathiesen, L. Elsgaard, K. Kristensen, S. E. Larsen, S. B. Torp, M. H. Greve |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 9, no. 1 ; Nr. 9, no. 1 (2012-01-23), S.403-422 |
| Datensatznummer |
250006673
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| Publikation (Nr.) |
 copernicus.org/bg-9-403-2012.pdf |
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| Zusammenfassung |
| The use of organic soils by agriculture involves drainage and tillage, and
the resulting increase in C and N turnover can significantly affect their
greenhouse gas balance. This study estimated annual fluxes of CH4 and
N2O, and ecosystem respiration (Reco), from eight organic soils
managed by agriculture. The sites were located in three regions representing
different landscape types and climatic conditions, and three land use
categories were covered (arable crops, AR, grass in rotation, RG, and permanent
grass, PG). The normal management at each site was followed, except that no N
inputs occurred during the monitoring period from August 2008 to October
2009. The stratified sampling strategy further included six sampling points
in three blocks at each site. Environmental variables (precipitation, PAR,
air and soil temperature, soil moisture, groundwater level) were monitored
continuously and during sampling campaigns, where also groundwater samples
were taken for analysis. Gaseous fluxes were monitored on a three-weekly
basis, giving 51, 49 and 38 field campaigns for land use categories AR, PG and
RG, respectively. Climatic conditions in each region during monitoring were
representative as compared to 20-yr averages. Peat layers were shallow,
typically 0.5 to 1 m, and with a pH of 4 to 5. At six sites annual
emissions of N2O were in the range 3 to 24 kg N2O-N ha−1, but
at two arable sites (spring barley, potato) net emissions of 38 and 61 kg
N2O-N ha−1 were recorded. The two high-emitting sites were
characterized by fluctuating groundwater, low soil pH and elevated
groundwater SO42− concentrations. Annual fluxes of CH4 were
generally small, as expected, ranging from 2 to 4 kg CH4 ha−1.
However, two permanent grasslands had tussocks of Juncus effusus L. (soft rush) in
sampling points that were consistent sources of CH4 throughout the
year. Emission factors for organic soils in rotation and with permanent
grass, respectively, were estimated to be 0.011 and 0.47 g m−2 for
CH4, and 2.5 and 0.5 g m−2 for N2O. This first documentation
of CH4 and N2O emissions from managed organic soils in Denmark
confirms the levels and wide ranges of emissions previously reported for the
Nordic countries. However, the stratified experimental design also
identified links between gaseous emissions and site-specific conditions with
respect to soil, groundwater and vegetation which point to areas of future
research that may account for part of the variability and hence lead to
improved emission factors or models. |
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