1. 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

2. 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 -200 -150 -100 -50 0 50 100 150 200 -300-250-200-150-100-50050100 local W  E scale [m] local S  N scale [m] Highway annual distribution of wind directions

3. 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

4. C-comp_time Vegetation Development and Management Events

5. C-budget result Carbon Budget for Intensive and Extensive Management (2002-2005)  C/  t CO 2 Harvest Manure

6. R_hetero (lab) Heterotrophic Soil Respiration (incubated soil cores at 25°C)

7. 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

8. Foto gradient Gradient system for NH 3 Static chamber system for N 2 O Dynamic chamber system for NO / NO 2

9. Cumulative NH 3 Exchange (INT field)

10. N-budet result Annual N-Budget for Intensive and Extensive Management

11. ..... C-Budget....

12. comp N-budget Comparison of N-Budget Estimates

13. 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)

14. End Thank You