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| Titel |
Influence of agricultural management on nitrous oxide emissions: comparison of different modelling approaches |
| VerfasserIn |
C. Klier, S. Gayler, C. Haberbosch, R. Ruser, R. Stenger, H. Flessa, E. Priessack |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250037938
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| Zusammenfassung |
| Intensive agricultural land use is considered to be the major source of the anthropogenic
contribution to the increase in atmospheric nitrous oxide (N2O) concentration during the last
decades. Mathematical models help to understand interacting processes in the nitrogen cycle
and state variables affecting N2O emissions. Most of the simulation models which have been
used to estimate N2O emissions from soils under field conditions represent the underlying
processes of denitrification or nitrification by first order rates without modelling the gaseous
N2O transport process. In the first part of the study we compare two modelling approaches of
the modular nitrogen modelling system Expert-N for their ability to describe and quantify the
seasonal variations of N2O fluxes in a potato-cropped soil. Model 1 assumes a fixed
N2O:N2 ratio for N2O production and neglects the transport of N2O in the soil profile,
Model 2 explicitly considers a N2O transport and assumes a dynamic reduction
of N2O to N2. Data for model evaluation arise from an experiment, where N2O
fluxes were monitored over the vegetation period, using a closed chamber technique.
Experimental results showed a variation of N and O2 supplies between the ridge soil
and inter-row soil of the potato plantation and a corresponding impact on N2O
release to atmosphere. Thus, in the second part of the study we applied a multiregion
modelling approach to get a spatially explicit modelling tool. In the multiregion
approach a heterogeneous soil hydraulic regime is subdivided into finite, multiple,
hydraulically interacting regions in the form of soil columns. Modelling results
showed for the first part of the study that both modelling approaches were able to
describe the observed seasonal dynamics of N2O emissions and events of high N2O
emissions due to increased denitrification activity after heavy precipitation and fertiliser
application. Extremely high emission rates from the inter-row soil of the potato
plantation were underestimated by both models. The lower N2O release from the ridge
soil was mainly due to a better aeration because of a lower soil bulk density and
lower water contents caused by lateral run-off and root water uptake. This could be
shown by the application of the multiregion approach in the second part of the study. |
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