p. 1Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
CH4 emission in agriculture, estimates
and mitigation practices
J.L. Peyraud
p. 2Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
General considerations
on methane emissions
p. 3Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
On farm GHG emission of Livestock sector
Sectors % total
AgricultureLivestock
107
Industry* 38
Transport 21
Tertiary 12
* Including manufacture of mineral N fertilizerEuropean Environment Agency, 2019 - mean 2003-2018
Livestock emissions(Gt CO2-eq)
Europe 0.25
World 8.144
95
37
8
(FAO, 2019)
https://www.eea.europa.eu/data-and-maps/data/data-viewers/greenhouse-gases-viewer,
• Reducing agricultural GHG emissions would require as a priority diminishing enteric CH4 and soil N2O emissions.
p. 4Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
Cattle number (Eu-15)
Evolution of on farm CH4 emission of EU livestock sector
Enteric + manure CH4 (Tg/an)
CH4 livestock (% CH4 total)
- 1.5 %/year
https://www.eea.europa.eu/data-and-maps/data/data-viewers/greenhouse-gases-viewer (2021)
p. 5Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
• The calculation of CO2-eq misrepresents the role of CH4 in global warming• Biogenic CH4 is part of a natural C cycle• CH4 is a short life (9±2 y) vs CO2 and N20 • CH4 do not accumulate in the atmosphere if
the rate of emission is constant• N2O still continue to accumulate even
though emissions are slowly being reduced
Rethinking CH4: livestock’s path to climate neutrality
• What consequences? • No additional warming if the rate of CH4 emission is constant or decrease !
• Reducing CH4 emissions will have a very important short-term effect (cooling effect ≈
storage of C as planting trees): an opportunity for the ruminant to reach climate neutrality
• Avoid any increase in emissions (and therefore in ruminant numbers)
p. 6Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
Emissions sources in bovine farms
• Enteric CH4
• Manure management (CH4, N2O)• Feed production (N2O)• Machinery & energy (CO2)
p. 8Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
Reduction of livestock production
• A rapid reduction of emissions according to the Tier 1 method
• But unintended effects may arise
• Increase in global CH4 emissions • Decrease in grassland area with subsequent soil C and biodiversity losses
Mill
ion
ha
and
co
ws
(EE-
9)
p. 9Autonomie en protéines pour l’élevage français : Quelles perspectives J.L. Peyraud
Enteric CH4: Feed additives
Mitigation(%/kg product)
Comments
PUFA (omega-3) • 15 to 20%, • Persistent effect
• Increase nutritional value of milk and meat• Distribution (extensive systems)?
Chemical inhibitors: (methyl) 3NOP (DSM)
• 20 to 30%, • Persistent effect
• Residues in animal products? • Not yet marketed• Distribution?
Tannins • 0 to < 20 % (trefoil) • Effects depends of the origin of tannins• Other unexpected effects on digestion (+/-)
Red algae • Up to 80% (Roque et al., 2021) • Need to be confirmed
• Consequences on the production cost, market valuation?
(adapted from Doreau et al, 2011; Patra et al, 2017)
p. 10Autonomie en protéines pour l’élevage français : Quelles perspectives J.L. Peyraud
Enteric CH4: Feeding practices
Mitigation(%/kg product)
Comments
Use of forage legumes • 5% (Luscher et al., 2014)
• Persistent effect• Mitigation of N2O• Protein autonomy whatever the system
High proportion of starchy concentrate
• 0 to 10% (dairy) (INRAe, 2018)
• < 10% beef production• Feed vs food competition, cost • Acidosis
Precision livestock feeding
• 10% ? • Avoid overconsumption of feed• Intensive systems with confined animals
Modifying the microbial ecosystem
• ? • Need to be explored. First results areencouraging
p. 11Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
Enteric CH4: Herd management
Mitigation(%/kg product)
Comments
Low emitting animals • ? • Antagonism with the efficiency of digestion: The most efficient animals seem to have better cellulose digestibility and produce more CH4
(Renan et al., 2016 ; Mc Donnell et al., 2016)
Age at first calving (28-30 to 24 months)
• 5 : dairy sector • More difficult for beef sector (breed precocity)
Culling rate (35-40 to 25%) • 10% dairy sector • Very few possibilities for suckler cows
CH4/DMI
LWG/DMI
p. 12Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
Manure CH4 : Ruminants and non ruminants
Mitigation(% manure emission)
Comments
Reduction of storage time • 10% • Reduction of NH3 emission
Rapid burial • < 10% • Reduction of NH3 emission
Biogas production • Huge potential : A production potential of primary energy close to French hydroelectric production (Elba, 2018).
p. 13Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
Soil C sequestration
• C Sequestration represents compensation in a range of 20 to 60% of C footprint or 40 to 80% of enteric CH4
• Potential for additional sequestration
4P1000 study (Pellerin et al., 2019)
Direct seeding
Insertion of cover crops
Organic amendments
Crops rotation with grasslands
C sequestration (Mg C/ha/year)
0 0.2 0.4 0.6
• Livestock and grassland have strong potential for increasing soil C sequestration
p. 14Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
- 50% GHG
(CH4)
N2O emissions
En & protein
autonomy
Bio-diversity
+ 25% Organic farming
National inventories
Reduction of ruminant production + 0/- + - + +
Methane inhibitors + 0 0 0 0 -
Use of forage legumes + + + + + -
Precision livestock farming + + + 0/+ 0 -
Age at first calving reduced culling rate + + + 0 + +
Smart use of manure + + + 0/+ + + (EF)
Biogas production + + + 0 0 +
Soil C sequestration + 0 0 0 0 +
Are there winning strategies between CH4 mitigation
practices and other objectives of the Green deal?
p. 15Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
How to facilitate adoption of
mitigation practices?
p. 16Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
Role of public policies and actors of the supply chains
Comments
Tax meat (GHG and health) • Mitigation of N2O not considered• Transfer to non ruminant meat (increase in feed vs food
competition) and/or to cheaper ultra-processed food
Tax GHG emissions • Tackle the 2 major GHG sources : livestock and mineral fertilizers• N2O tax > CH4 tax (long vs short live pollutant)
Certified emission reduction units, “C market”
• Positive approach, farmers are paid for progress• On farm implementation of mitigation projects (Hyland et al., 2017)
• PP: approbation of practices, certification of diagnostic tools• The interest will increase with the price of C
C labelling • Private actors can differentiate themselves
Rewarding grassland for the public goods they provide
• Soil C sequestration, preservation of biodiversity
(Peyraud and Mc Leod, 2021)
p. 18Expert Group “Methane Emissions in Agriculture”s J.L. Peyraud 28 May 2021
• CH4 mitigation options
• While intense research into enteric emission mitigation is conducted few commercially proven and cost-effective solution are yet available: from experiment to real live (lower mitigation…• Feed additive seems to be efficient• Precision livestock farming: need further evaluation beyond the proof of concept,• Low emitting animals, manipulation of microbial ecosystem: still prospective,
• Some win-win practices: use of legume forage, improved herd management (cow longevity and health), smart use of manure, production of green energy,
• Improving practices are generally easier to deploy in intensive systems than in extensive systems for which it is essential to account for the C sequestration in the inventories
• Most of the practices have additive effects.
• Public policies to stimulate the development of mitigation practices • Rethinking the role of CH4 in climate change: different policies could be set for CH4 and N2O,
• Developing, stimulating positive approaches for the farmer point of view vs new tax
• The different tools are not mutually exclusive,
• Implementation of practices well adapted to the local context (C market) make progress more
difficult to trace back in national inventories,