Methane: the issue, the Methane: the issue, the Science, the SolutionScience, the Solution

Roger CohenRoger Cohen

Department of Animal & Poultry ScienceDepartment of Animal & Poultry Science

University of SaskatchewanUniversity of Saskatchewan

Focus on beef cattleFocus on beef cattle

““Cattle production and beef consumption now Cattle production and beef consumption now rank among the gravest threats to the future rank among the gravest threats to the future well-being of the earth and its human well-being of the earth and its human population”population”

•Rifkin (1992) - Beyond beef: The rise and fall of Rifkin (1992) - Beyond beef: The rise and fall of the cattle culturethe cattle culture

• Ryan Eliason (undated) - YES HandbookRyan Eliason (undated) - YES Handbook

““Cattle and other livestock account for twice Cattle and other livestock account for twice the amount of pollutants as come from all the amount of pollutants as come from all U.S. industrial sources”U.S. industrial sources”

““Livestock production is perhaps the most Livestock production is perhaps the most massive force behind the destruction of our massive force behind the destruction of our planet”planet”

The earth’s climate is changingThe earth’s climate is changing

Significant changes during 20th centurySignificant changes during 20th century

• The cause is the enormous increase in The cause is the enormous increase in anthropomorphic emission of greenhouse anthropomorphic emission of greenhouse gases (GHG)gases (GHG)

•Carbon dioxideCarbon dioxide

•Nitrous oxideNitrous oxide

•MethaneMethane

Carbon dioxideCarbon dioxide

Important sources are:Important sources are:

- Burning of fossil fuels (coal & petroleum)- Burning of fossil fuels (coal & petroleum)

- clearing and burning forests for crop - clearing and burning forests for crop and livestock productionand livestock production

Nitrous oxideNitrous oxide

• Important sources are:Important sources are:- Application of nitrogen fertilizer - Application of nitrogen fertilizer - Soil disturbance- Soil disturbance

• Crop production most responsible Crop production most responsible Alleviated byAlleviated by - Deep banding - Deep banding

- Zero till- Zero till

• Little use on pasture - legumes preferredLittle use on pasture - legumes preferred

MethaneMethane

• By-product of anaerobic decomposition By-product of anaerobic decomposition of organic matterof organic matter

•Important Non-anthropomorphic sources:Important Non-anthropomorphic sources:- wetlands - wetlands - Forest fires- Forest fires

• Important agricultural sources:Important agricultural sources:Rice farmingRice farmingRuminant livestockRuminant livestockManure (all species)Manure (all species)

• Other anthropomorphic sources:Other anthropomorphic sources:- Human waste- Human waste

Landfills, sewage, waste waterLandfills, sewage, waste water- Fossil fuel industry- Fossil fuel industry

Natural gas, petroleum Natural gas, petroleum processing,processing,

coal miningcoal mining

Global Warming Potential of GHGGlobal Warming Potential of GHG

CO2 CH4

N2O

Radiative forcing relative to CORadiative forcing relative to CO22 11 5858 206 206

Lifetime (years)Lifetime (years) 120120 1010 150150

GWP in 100 years relative to COGWP in 100 years relative to CO22 1 1 2121 290 290

Global Emissions (Gt/yr) Global Emissions (Gt/yr) aa 21.921.9 0.5 0.5 0.0210.021

Global Emissions (GWP) Global Emissions (GWP) bb 21.921.9 10.510.5 6.1 6.1a 1 Gt = 1 billion tonnes

b Potential for a unit of gas for warming the world

Wetlands

Humans

Forest fires

Cattle

Manure

Natural gas leaks

Other

82.77%

6.59%

3.38%

2.89%

1.14% 0.98%

2.25%

Figure 1. Sources of methane in Canada as a percent of the total methane emission

Sources of methane in Canada as a Sources of methane in Canada as a percentage of total methane emissionspercentage of total methane emissions

Biomass

Other industry

Coal mining

Fuel combustion

Natural gas leaks

Manure

Other domestic animals

Wild animals

Cattle

Forest fires

Humans

Humans

Forest fires

Cattle

38.3%

19.6%

16.8%

Sources of methane in Canada excluding Sources of methane in Canada excluding wetlandswetlands

Domestic livestock account for about 30% of Domestic livestock account for about 30% of anthropomorphic methane emissions in North anthropomorphic methane emissions in North America. Main sources are:America. Main sources are:

• Eructated gas from ruminants (Cattle & sheep)Eructated gas from ruminants (Cattle & sheep)

• ManureManure

Are cattle a major cause of climate warming Are cattle a major cause of climate warming or can they be part of the solution?or can they be part of the solution?

Recycling carbon through plants Recycling carbon through plants and animals is an important part of and animals is an important part of the solution to the GHG problemthe solution to the GHG problem

• COCO22 taken up by plants and stored in leaves, taken up by plants and stored in leaves,

stems and roots as carbohydrates (cellulose, stems and roots as carbohydrates (cellulose, hemicellulose,lignin)hemicellulose,lignin)

• Cattle eat leaves and stems and return 25-60% Cattle eat leaves and stems and return 25-60% of the Carbon to soil in fecesof the Carbon to soil in feces

• Incorporated into soil organic matter which Incorporated into soil organic matter which enhances physical & chemical characteristics enhances physical & chemical characteristics of the soil encouraging further plant growthof the soil encouraging further plant growth

• Most important role in recycling carbon Most important role in recycling carbon belongs to the roots because they carry the belongs to the roots because they carry the carbon directly into the soilcarbon directly into the soil

Two categories of plants Two categories of plants used in agricultureused in agriculture

• Perennial grasses and legumes used for Perennial grasses and legumes used for ruminant livestock feed (73% of beef cattle feed)ruminant livestock feed (73% of beef cattle feed)

• Annual plants (cereal, oilseed & pulse Annual plants (cereal, oilseed & pulse crops etc.)crops etc.)

Perennial plantsPerennial plants

• Deep extensive root systemDeep extensive root system

• Dry matter below ground (roots carbon) = Dry matter below ground (roots carbon) = DM above ground (leaves + stems carbon)DM above ground (leaves + stems carbon)

• About 50% of roots die and regenerate each About 50% of roots die and regenerate each year burying carbon deep in the soilyear burying carbon deep in the soil

• Channels from decayed roots improve Channels from decayed roots improve moisture penetration and plant growthmoisture penetration and plant growth

• Proper defoliation (grazing or mechanical) Proper defoliation (grazing or mechanical) stimulates new growth of leaves, stems, rootsstimulates new growth of leaves, stems, roots

• Incorrect defoliation (severe, wrong time) will Incorrect defoliation (severe, wrong time) will weaken the plant which will eventually disappear weaken the plant which will eventually disappear

• Careful management of defoliation is therefore Careful management of defoliation is therefore critical to the mitigation of climate changecritical to the mitigation of climate change

Annual plantsAnnual plants

• Shallow rootsShallow roots

• Above ground carbon >> below ground Above ground carbon >> below ground

• Much of the carbon is removed from the Much of the carbon is removed from the system in the harvested material (grain)system in the harvested material (grain)

• Net depletion of soil organic matter Net depletion of soil organic matter (carbon) over time(carbon) over time

Carbon sequestration Carbon sequestration enhanced by:enhanced by:

• Replacing degraded crop land with Replacing degraded crop land with permanent pasturepermanent pasture

• Incorporating perennial forages (pasture/hay) Incorporating perennial forages (pasture/hay) into crop rotationsinto crop rotations

Benefits other than removal of Benefits other than removal of atmospheric carbon include:atmospheric carbon include:

• Reduced land degradation from wind and Reduced land degradation from wind and water erosionwater erosion

• Increased soil organic matter, fertility & Increased soil organic matter, fertility & water holding capacitywater holding capacity

• Soil salinity is checkedSoil salinity is checked

• Deep water penetration is increasedDeep water penetration is increased

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

What about the methane What about the methane emitted by cattle?emitted by cattle?

• The carbon in this source of methane is The carbon in this source of methane is not “new” carbon - it is recycled carbonnot “new” carbon - it is recycled carbon

• Methane emitted by the coal and Methane emitted by the coal and petroleum industries is “new” carbonpetroleum industries is “new” carbon

60 million bison roamed the northern 60 million bison roamed the northern great plains before settlementgreat plains before settlement

Today there are only about 32 million Today there are only about 32 million cattle in the northern great plains regioncattle in the northern great plains region

Carbon balance in a mixed native Carbon balance in a mixed native grass pasture grazed by 1 cow and grass pasture grazed by 1 cow and calf on 2 ha (5 ac)calf on 2 ha (5 ac)

CARBON SINKS:CARBON SINKS:

• Atmospheric COAtmospheric CO22 taken up by pasture taken up by pasture

• Atmospheric CHAtmospheric CH44 absorbed by soil absorbed by soil

• Manure C incorporated into soilManure C incorporated into soil

• C in pasture eaten by cow and calfC in pasture eaten by cow and calf

• C passed from cow to calf in milkC passed from cow to calf in milk

• C retained by calf as growthC retained by calf as growth

CARBON SOURCES:CARBON SOURCES:

• Respired CORespired CO2 2 from cow and calffrom cow and calf

• Eructated COEructated CO2 2 from cow and calffrom cow and calf

• Eructated CHEructated CH4 4 from cow and calffrom cow and calf

• CHCH4 4 from manure of cow and calffrom manure of cow and calf

• COCO2 2 from manure of cow and calffrom manure of cow and calf

• CHCH4 4 from decomposition of plant matterfrom decomposition of plant matter

Total carbon sources = 2.99 kg C / dTotal carbon sources = 2.99 kg C / d

Total carbon sinks = 20.73 kg C / dTotal carbon sinks = 20.73 kg C / d

GWP of COGWP of CO22 and CH and CH44 = 1 and 21 = 1 and 21

Removal of GWP gases by cow & calf Removal of GWP gases by cow & calf = 20.65 units / d= 20.65 units / d

Emission of GWP gases by cow & calfEmission of GWP gases by cow & calf= 6.46 unit / d= 6.46 unit / d

Net reduction in GWP = 14.19 units / dNet reduction in GWP = 14.19 units / d

In a single grazing season of 150 In a single grazing season of 150

days this is a REMOVAL ofdays this is a REMOVAL of

2,127.9 units of GWP gases 2,127.9 units of GWP gases from the atmospherefrom the atmosphere

Assuming that the cow & calf emit a similar Assuming that the cow & calf emit a similar amount of COamount of CO22 and CH and CH44 to the atmosphere for to the atmosphere for

the remaining 215 days of the year and that the remaining 215 days of the year and that there is no removal of COthere is no removal of CO22 and CH and CH44 from the from the

atmosphere by pasture and soil during winter:atmosphere by pasture and soil during winter:

Total sources of GWP gases = Total sources of GWP gases = 2,359 units / year2,359 units / year

Total sinks of GWP gases = Total sinks of GWP gases = 3,098 units / year3,098 units / year

Net removal of GWP gases = 739 units / yearNet removal of GWP gases = 739 units / year

Grazing beef cattle are an integral Grazing beef cattle are an integral part of climate change mitigationpart of climate change mitigation

CONCLUSIONCONCLUSION

Policy recommendationsPolicy recommendations

• Support for grazing management research & Support for grazing management research & extensionextension

• Encourage correct management of all pasture Encourage correct management of all pasture lands through research and extensionlands through research and extension

• Encourage return degraded crop land to Encourage return degraded crop land to permanent pasturepermanent pasture

• Encourage integration of perennial forage into Encourage integration of perennial forage into cropping practicescropping practices

• Encourage more backgrounding and finishing of cattle Encourage more backgrounding and finishing of cattle on pastureon pasture