Titel C- and N-budgets of managed grassland Swiss CarboEurope/NitroEurope site C. Ammann, A. Neftel, C. Flechard, C. Spirig, J. Fuhrer Agroscope ART Research Station, Zürich, Switzerland CarboEurope-IP Meeting, Poznan, 2007 Federal Research Station Agroscope ART
Site Fields Oensingen Field Site Intensively managed grassland mineral fertilizer and manure (ca. 200 kg/ha/y total N) 4-5 cuts per year Extensively managed grassland no fertilizer 3 cuts per year Various crops (rotation) Eddy covariance systems local W E scale [m] local S N scale [m] Highway annual distribution of wind directions
C-budget concept Components of the Grassland Carbon Budget (forage production, no grazing) C/ t carbon sequestration: C/ t CO 2 exchange (NEE) harvest manure = ( import/export processes ) = NBP
C-comp_time Vegetation Development and Management Events
C-budget result Carbon Budget for Intensive and Extensive Management ( ) C/ t CO 2 Harvest Manure
R_hetero (lab) Heterotrophic Soil Respiration (incubated soil cores at 25°C)
N-Budget NO/NO 2 - Exchange N 2 O – Emission and Uptake NH 3 – bidirectional exchange Run-off (dissolved NO 3 - ) N 2 – Fixation N-content in manure and synthetic fertilizer 3 dynamic chambers 4 automated static chambers 15 N isotopic labelling on 6 subplots Gradient system (2 AiRRmonia units) N content in harvest biomass 2 suction cups Oensingen Site: N-Budget Components Wet Depostion Wet-only sampler N 2 – total Denitrification incubation with acetylene
Foto gradient Gradient system for NH 3 Static chamber system for N 2 O Dynamic chamber system for NO / NO 2
Cumulative NH 3 Exchange (INT field)
N-budet result Annual N-Budget for Intensive and Extensive Management
..... C-Budget....
comp N-budget Comparison of N-Budget Estimates
comp N-budget Conclusions A carbon sequestration is only observed for the fertilized grassland (high N input). The net carbon loss of the extensive field is probably due to an enhanced decomposition of soil organic matter ( N mobilisation due to lack of fertilisation) The carbon sequestration of the intensive field is partly (c. 20%) compensated by emission of N 2 O (due to fertiliser application)
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