1. THE CONSEQUENCES OF INTERNATIONAL AGRICULTURAL RESEARCH ON GREENHOUSE GAS EMISSIONS AND GLOBAL CLIMATE CHANGE L.V. Verchot, P. Grace, P. Sanchez, J. Ingram, C. Palm, R. Wassman, M. Fisher, R. Thomas, F. Chandler, W. Bowen, R. Reid, M. Wopereis and S. Waddington [ L.Verchot@cgiar.org]

2. Background Food production has tripled in the last 30 years in developing countries This increase has been largely due to technological advances through improved varieties and intensification of agriculture

3. Questions What is the effect of increased agricultural productivity on: –Atmospheric GHG concentrations –Terrestrial C Have agricultural productivity gains mitigated or exacerbated climate forcing?

4. Approach: Case Studies Green Revolution: Global Analysis Alternatives to Slash and Burn: Humid tropics Improved pastures: South America Irrigation frequency in rice: Asia Irrigated rice systems: W. Africa Multiple cropping systems: S. Asia Fodder banks: W.Africa Tse-tse fly control: E. & S. Africa Fertilizer reduction in maize systems: S. Africa

5. Case Study The Green Revolution

6. GHG Emissions Included LUC soil: LUC biomass: N fertilizer application: N fertilizer production: Rice cultivation: Burning residues: Residue decomposition: Biological N fixation: Residue decomposition Rice cultivation CO 2 CO 2 CH 4 N 2 O N 2 O CH 4 CO 2 CH 4 CH 4 N 2 O N 2 O CH 4

7. GHG Emissions not Included CH 4 from livestock CH 4 and N 2 O from prescribed burning of savannas N 2 O from application of animal manures

8. Green Revolution Analysis Assumptions Cereal yields remain constant 1965-1995 Forest, then pastures used as new croplands FAOSTAT as data source GHG from available data or from IPCC default values for Asia, Africa and Latin America N fertilizer usage remains at 1965 levels

9. Area Required to Meet Cereal Production in 1995 with 1965 Yields RegionYield (t ha -1 )  Area (M ha) Area saved (M ha) 19651995+GR-GR+GR Saving Africa0.81.1275326 Asia1.42.948405358 LAC1.42.564842 Total81507426 Without the Green Revolution the cultivated area in Asia, Africa and Latin America would have doubled.

10. Above-ground Biomass Emissions Region CO 2 (Gt)CH 4 (Mt)N 2 O (Kt) +GR-GR+GR-GR+GR-GR Africa 4.69.015.530.7107211 Asia 4.5 15.4 106 LAC 2.07.06.823.747163 Total 11.120.537.769.8260480

11. Soil Emissions and Change in Soil C Stocks Region CO 2 (Gt)  C Stock (Gt) +GR-GR+GR-GR Africa 2.85.50.81.5 Asia 6.353.51.714.6 LAC 0.64.80.21.3 Total 9.763.82.717.4

12. GHG Emissions Due to LUC (Gt C/y, 1965-95) Source CO 2 from soil CO 2 from vegetation CH 4 from vegetation N 2 O from vegetation Total Saved from LUC +GR-GR 2.6 17.3 3.0 5.6 0.20.4 0.020.04 5.823.3 17.5

13. GHG Emissions Due to Intensification (Gt C/y, 1965-95) Source: Rice cultivation CH 4 N fertilizer application N 2 O N fertilizer production CO 2 Residue decomposition N 2 O Burning residues CH 4 +N 2 O Biological N fixation N 2 O Total emissions LU Saved from LU Intensification Green Revolution With Without 3.7 5.2 1.30.4 0.80.30.50.30.1 6.76.8 -0.1

14. Implications of Green Revolution Saved 426 million hectares of forests and grasslands from clearing If not, cultivated area would have about doubled in developing countries Saved 583 million tonnes C y -1 from all activities Equivalent to 1 / 3 of annual USA emissions (from ALL sources) Virtually all the savings were due to savings in land use change

15. Case Study Pasture Improvement in S. America

16. Background Pastures occupy 250 M ha in tropical SA Loss of aboveground biomass is trivial when grasslands are converted to pasture When forest is converted to pasture aboveground losses are high

17. Approach Replicated plots Poorly managed A. gayanus pasture (17 years old Well managed pasture of B. humidicola (18 years old) Measured soil C to 2 m depth

18. Soil C Stocks Depth (cm)SavannaA. gayanusB. humidicola 0 - 207.07.68.8 20 – 10012.614.717.9 total19.622.326.7 % deeper than 20 cm 646667

19. Potential C Accumulation in SA Pastures Made from Grasslands Total Pasture Area (Mha) Potential Accumulation (Mt) Br. Shield40.81713 Orinoco Basin Colombia0.24 Venezuela2.4 – 4.086 Total451803

20. Conclusions Well-managed pastures have the potential of accumulating significant C in the soil profile, compared to grasslands Even if we factor in degradation the accumulation is likely to exceed 900 Mt Conversion of forest to pasture will result in net C loss