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| Titel |
Modelling the effect of aggregates on N2O emission from denitrification in an agricultural peat soil |
| VerfasserIn |
P. C. Stolk, R. F. A. Hendriks, C. M. J. Jacobs, E. J. Moors, P. Kabat |
| 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 ; 8, no. 9 ; Nr. 8, no. 9 (2011-09-20), S.2649-2663 |
| Datensatznummer |
250006127
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| Publikation (Nr.) |
 copernicus.org/bg-8-2649-2011.pdf |
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| Zusammenfassung |
Nitrous oxide (N2O) emissions are highly variable in time, with high
peak emissions lasting a few days to several weeks and low background
emissions. This temporal variability is poorly understood which hampers the
simulation of daily N2O emissions. In structured soils, like clay and
peat, aggregates hamper the diffusion of oxygen, which leads to anaerobic
microsites in the soil, favourable for denitrification. Diffusion of
N2O out of the aggregates is also hampered, which leads to delayed
emissions and increased reduction of N2O to N2. In this model
simulation study we investigate the effect of aggregates in soils on the
N2O emissions. We present a parameterization to simulate the effects of
aggregates on N2O production by denitrification and on N2O
reduction. The parameterization is based on the mobile-immobile model
concept. It was implemented in a field-scale hydrological-biogeochemical
model combination. We compared the simulated fluxes with observed fluxes
from a fertilized and drained peat soil under grass.
The results of this study show that aggregates strongly affect the simulated
N2O emissions: peak emissions are lower, whereas the background
emissions are slightly higher. Including the effect of aggregates caused a
40% decrease in the simulated annual emissions relative to the
simulations without accounting for the effects of aggregates. The new
parameterization significantly improved the model performance regarding
simulation of observed daily N2O fluxes; r2 and RMSE improved from
0.11 and 198 g N2O-N ha−1 d−1 to 0.41 and 40 g N2O-N ha−1 d−1,
respectively. Our analyses of the model
results show that aggregates have a larger impact on the reduction than on
the production of N2O. Reduction of N2O is more sensitive to
changes in the drivers than production of N2O and is in that sense the
key to understanding N2O emissions from denitrification. The effects of
changing environmental conditions on reduction of N2O relative to
N2O production strongly depend on the NO3 content of the soil.
More anaerobic conditions have hardly any effect on the ratio of production
to reduction if NO3 is abundant, but will decrease this ratio if
NO3 is limiting. In the first case the emissions will increase, whereas
in the second case the emissions will decrease. This study suggests that the
current knowledge of the hydrological, biogeochemical and physical processes
may be sufficient to understand the observed N2O fluxes from a
fertilized clayey peatland. Further research is needed to test how
aggregates affect the N2O fluxes from other soils or soils with
different fertilization regimes. |
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