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| Titel |
Management matters: Testing a mitigation strategy of nitrous oxide emissions on managed grassland |
| VerfasserIn |
Kathrin Fuchs, Lukas Hörtnagl, Werner Eugster, Patrick Koller, Florian Käslin, Lutz Merbold |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250144285
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| Publikation (Nr.) |
 EGU/EGU2017-8094.pdf |
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| Zusammenfassung |
| The magnitude of greenhouse gas (GHG) exchange between managed grasslands and the
atmosphere depends besides climate predominantly on management practices. While natural
or extensively managed grasslands are known to function as GHG sinks, intensively managed
grasslands are characterized by substantial nitrous oxide (N2O) emissions diminishing their
sink function.
One potential N2O mitigation strategy is to reduce the required amount of nitrogen (N)
fertilizer input by using biological nitrogen fixation (BNF) via legumes. However, the effect
of legumes on nitrous oxide emissions is still not fully understood. In this study we quantify
net GHG fluxes from two differently managed grassland parcels (mitigation, control) and
relate our results to productivity (yields). In addition, we aim at revealing the influence of
various driver variables on N2O exchange.
Our experimental setup consisted of an eddy covariance tower that measured the net
exchange of the three major anthropogenic GHGs, nitrous oxide (N2O), methane (CH4) and
carbon dioxide (CO2). Both grassland parcels can be covered with this tower due to two
prevailing wind directions. GHG flux measurements were accompanied by measurements of
commonly known driver variables such as water filled pore space, soil temperature, soil
oxygen concentrations and mineral N to disentangle the soil meteorological influence of N2O
fluxes from human drivers.
Following organic fertilizer application, we measured elevated N2O emissions (>1 nmol
m−2 s−1) at the control parcel and unchanged N2O emissions at the treatment
parcel. Net annual fluxes were 54% and 50% lower at the experimental parcel in
2015 and 2016, respectively. Annual yields did not significantly differ between
parcels, but were slightly lower at the experimental parcel compared to the control
parcel.
Significantly lower nitrous oxide fluxes under experimental management indicate that
nitrous oxide emissions can be effectively reduced at very low costs with a clover-based
management. Long-term effects on the N budget, implications for the quality of animal feed
as well as potential consequences at the farming system level (i.e. manure management) need
further evaluation. |
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