Opportunities for Carbon Sequestration in Irish Grasslands

1. Opportunities for Carbon Sequestration in Irish Grasslands Vesna Jakšić Supervisors: G. Kiely, University College Cork O. Carton, D.Fay, Johnstown Castle Dublin, 20/11/2003

2. Opportunities for Carbon Sequestration in Irish Grasslands Why study atmosphere Carbon Dioxide ? • The Kyoto Protocol for Ireland requires that emissions of GHG must be no more than 13% above the 1990 levels • As of 2001, emissions are 31% greater than the 1990 levels (EPA) • By 2008 – 2012 the “business as usual” scenario forecast (produced in 2000 based on 1998 data) is that emissions may be more than 37% greater than the 1990 levels (NCCS) • Agricultural is responsible for about 27% (soils 5.5%) in 2001 of emission (EPA)

3. Air Sink Source Soil C sequestration Opportunities for Carbon Sequestration in Irish Grasslands Question ? Are agricultural soils sources or sinks for carbon ?

4. Opportunities for Carbon Sequestration in Irish Grasslands Budget of Carbon for a farm NEE – (A + B + C+…) = Csoil NEE = Net Ecosystem exchange in T of C/ha NEE = GPP – Rh – Ra A, B, C… = carbon leaving the farm (in milk, in meat, in enteric fermentation etc.) Csoil = the carbon fixed to the soil or lost to the atmosphere?

5. Opportunities for Carbon Sequestration in Irish Grasslands Objectives of project • Measure and model the CO2 flux at grasslands in Dripsey (Cork) and Johnstown Castle (Wexford) • Investigate seasonal, annual and interannual fluxes • Estimate the carbon budget at farm scale and so determine if the soils are sinks or sources of carbon

6. red dots ↔ site areas Opportunities for Carbon Sequestration in Irish Grasslands Sites • Cork grassland – Dripsey • Elevation ~ 190masl • Annual rainfall ~ 1450mm Wind Rose Downwind direction is SW

7. The automatic weather station– tower in full height Top of the tower with instruments Sonic anemometer Net radiometer Temperature and relative humidity probes at 3m LICOR H2O/CO2 sensor Perimeter for soil moisture, soil temperature and soil heat flux probes Rain gauge LICOR electronics box Opportunities for Carbon Sequestration in Irish Grasslands NEE – Eddy Covariance System

8. Sonic anemometer LI-7500 Open Path CO2/H2O gas analyser Opportunities for Carbon Sequestration in Irish Grasslands Eddy Covariance

9. Estimated footprint N Opportunities for Carbon Sequestration in Irish Grasslands Footprint area

10. Opportunities for Carbon Sequestration in Irish Grasslands CO2 flux measurements • July 2001 to Jun 2003 (the results for 24 months) • The site is intensive cattle grassland (Livestock density 2.2 LU/ha) with mix of grazing and silage • Nitrogen in chemical fertilizer was applied at the rate of 190kgN/ha and N in slurry approximately 90kgN/ha for the year 2002

11. August 2002 Net Respiration Net Photosynthesis Opportunities for Carbon Sequestration in Irish Grasslands Raw CO2 flux data @ 30 minute intervals

12. SINK SOURCE Soil porosity 48% Opportunities for Carbon Sequestration in Irish Grasslands CO2 flux and soil moisture

13. Opportunities for Carbon Sequestration in Irish Grasslands Cumulative uptakeT Carbon/ha

14. Opportunities for Carbon Sequestration in Irish Grasslands Cumulative uptakeT Carbon/ha Year 2002

15. Opportunities for Carbon Sequestration in Irish Grasslands Some NEE values

16. Opportunities for Carbon Sequestration in Irish Grasslands Carbon leaving the farm • Carbon in milk [t.C/ha.yr.] • average production 7500L/ha. • density φ = 1.03kg/L • carbon in milk = 4.5% CA= 0.35 T.C/ha. • Carbon in meat [t.C/ha.yr.] • ~18% of live weight • 1LU = 520kg pasture dry matter per year • Stocking Density for Dripsey = 2.2LU/ha • Assume that 1/3 of animals leave farm for the meat factory CB≈ 0.1 T.C/ha

17. Opportunities for Carbon Sequestration in Irish Grasslands Carbon leaving the farm • Carbon in CH4 respired from animal and CH4 from manure for full year • 100kg CH4 from animal • 15kg CH4 from manure • Stocking Density for Dripsey = 2.2LU/ha CC = 0.20T.C/ha. • Carbon as CO2 from respiring animal indoors for 4 months of year • Diet = 10kgDM/day/LU • DM = 45%Carbon • Assume 40% respire CD = 0.45 T.C/ha

18. CO2 Atmosphere Net Ecosystem Exchange NEE -2.5 T.C/ha/yr C as CO2 from respiring animal indoors for 4 months of year +0.45 T.C/ha/yr C in milk export +0.35 T.C/ha/yr C as CH4 from animal +0.2 T.C/ha/yr C in meat export +0.1 T.C/ha/yr C as CH4 from yard manure / slurry +0.1 T.C/ha/yr C as DOC/DIC in stream +0.1 T.C/ha/yr Canopy Soil Sequestration -1.2 T.C/ha/yr Soil Opportunities for Carbon Sequestration in Irish Grasslands Carbon Budget

19. Opportunities for Carbon Sequestration in Irish Grasslands Conclusions • Preliminary results suggest that there may be opportunities for Carbon sequestration in grassland soils • For 8 months (Mar to Oct) the site is a sink of carbon • Interannual variability of NEE is significant • (2.2 to 3.7 T of C/ha.yr) – need long term measurements • Preliminary results – carbon sequestration for 2002 • at Cork site is 1.2 T of C/ha.yr (forestry 3 to 6 T of C/ha)

20. Opportunities for Carbon Sequestration in Irish Grasslands Acknowledgements • Teagasc Walsh Fellowship Programme • Environmental Protection Agency • O. Carton and D. Fay, Environment and Land Use Department Teagasc Johnstown Castle • G. Kiely, University College Cork