Methane: the issue, the Science, the Solution

1. Methane: the issue, the Science, the Solution Roger Cohen Department of Animal & Poultry Science University of Saskatchewan

2. Focus on beef cattle Rifkin (1992) - Beyond beef: The rise and fall of the cattle culture “Cattle production and beef consumption now rank among the gravest threats to the future well-being of the earth and its human population”

3. Ryan Eliason (undated) - YES Handbook “Cattle and other livestock account for twice the amount of pollutants as come from all U.S. industrial sources” “Livestock production is perhaps the most massive force behind the destruction of our planet”

4. The earth’s climate is changing • Significant changes during 20th century The cause is the enormous increase in anthropomorphic emission of greenhouse gases (GHG) Carbon dioxide Nitrous oxide Methane

5. Carbon dioxide • Important sources are: - Burning of fossil fuels (coal & petroleum) - clearing and burning forests for crop and livestock production

6. Nitrous oxide Important sources are: - Application of nitrogen fertilizer - Soil disturbance Crop production most responsible Alleviated by - Deep banding - Zero till Little use on pasture - legumes preferred

7. Methane • By-product of anaerobic decomposition of organic matter • Important Non-anthropomorphic sources: - wetlands - Forest fires

8. Important agricultural sources: Rice farming Ruminant livestock Manure (all species) Other anthropomorphic sources: - Human waste Landfills, sewage, waste water - Fossil fuel industry Natural gas, petroleum processing, coal mining

9. Global Warming Potential of GHG CO2CH4N2O Radiative forcing relative to CO21 58 206 Lifetime (years)120 10 150 GWP in 100 years relative to CO2 1 21 290 Global Emissions (Gt/yr) a21.9 0.5 0.021 Global Emissions (GWP) b21.9 10.5 6.1 a 1 Gt = 1 billion tonnes b Potential for a unit of gas for warming the world

10. Sources of methane in Canada as a percentage of total methane emissions

11. Sources of methane in Canada excluding wetlands

12. Domestic livestock account for about 30% of anthropomorphic methane emissions in North America. Main sources are: Eructated gas from ruminants (Cattle & sheep) Manure • Are cattle a major cause of climate warming or can they be part of the solution?

13. Recycling carbon through plants and animals is an important part of the solution to the GHG problem • CO2 taken up by plants and stored in leaves, stems and roots as carbohydrates (cellulose, hemicellulose,lignin) Cattle eat leaves and stems and return 25-60% of the Carbon to soil in feces

14. Incorporated into soil organic matter which enhances physical & chemical characteristics of the soil encouraging further plant growth Most important role in recycling carbon belongs to the roots because they carry the carbon directly into the soil

15. Two categories of plants used in agriculture • Perennial grasses and legumes used for ruminant livestock feed (73% of beef cattle feed) Annual plants (cereal, oilseed & pulse crops etc.)

16. Perennial plants • Deep extensive root system Dry matter below ground (roots carbon) = DM above ground (leaves + stems carbon) About 50% of roots die and regenerate each year burying carbon deep in the soil Channels from decayed roots improve moisture penetration and plant growth

17. Proper defoliation (grazing or mechanical) stimulates new growth of leaves, stems, roots Incorrect defoliation (severe, wrong time) will weaken the plant which will eventually disappear Careful management of defoliation is therefore critical to the mitigation of climate change

18. Annual plants • Shallow roots • Above ground carbon >> below ground • Much of the carbon is removed from the system in the harvested material (grain) • Net depletion of soil organic matter (carbon) over time

19. Carbon sequestration enhanced by: • Replacing degraded crop land with permanent pasture Incorporating perennial forages (pasture/hay) into crop rotations

20. Benefits other than removal of atmospheric carbon include: • Reduced land degradation from wind and water erosion Increased soil organic matter, fertility & water holding capacity Soil salinity is checked Deep water penetration is increased

21. It is the relative inefficiency of producing beef from pasture that makes it the most sustainable form of agricultural production

22. What about the methane emitted by cattle? • The carbon in this source of methane is not “new” carbon - it is recycled carbon Methane emitted by the coal and petroleum industries is “new” carbon

23. 60 million bison roamed the northern great plains before settlement Today there are only about 32 million cattle in the northern great plains region

24. Carbon balance in a mixed native grass pasture grazed by 1 cow and calf on 2 ha (5 ac) • CARBON SINKS: Atmospheric CO2 taken up by pasture Atmospheric CH4 absorbed by soil Manure C incorporated into soil C in pasture eaten by cow and calf C passed from cow to calf in milk C retained by calf as growth

25. CARBON SOURCES: Respired CO2 from cow and calf Eructated CO2 from cow and calf Eructated CH4 from cow and calf CH4 from manure of cow and calf CO2 from manure of cow and calf CH4 from decomposition of plant matter

26. Total carbon sinks = 20.73 kg C / d • Total carbon sources = 2.99 kg C / d GWP of CO2 and CH4 = 1 and 21 Removal of GWP gases by cow & calf = 20.65 units / d Emission of GWP gases by cow & calf = 6.46 unit / d Net reduction in GWP = 14.19 units / d

27. In a single grazing season of 150 days this is a REMOVAL of 2,127.9 units of GWP gasesfrom the atmosphere

28. Assuming that the cow & calf emit a similar amount of CO2 and CH4 to the atmosphere for the remaining 215 days of the year and that there is no removal of CO2 and CH4 from the atmosphere by pasture and soil during winter: Total sources of GWP gases = 2,359 units / year Total sinks of GWP gases = 3,098 units / year Net removal of GWP gases = 739 units / year

29. CONCLUSION Grazing beef cattle are an integral part of climate change mitigation

30. Policy recommendations Support for grazing management research & extension Encourage correct management of all pasture lands through research and extension Encourage return degraded crop land to permanent pasture Encourage integration of perennial forage into cropping practices Encourage more backgrounding and finishing of cattle on pasture