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11Dublin, 25/06/2010
Mitigation of greenhouse gasemissions in Agriculture:
A UK perspective
Rees RM, MacLeod MJ, Moran D, McVittie A, Jones G, Harris D, Anthony S,Wall E, Eory V, Barnes A, Jones J, Topp CFE, Ball BC, Hoad S and Eory L
The UK’s greenhouse gasinventoryThe UK’s greenhouse gasinventory
• Agriculture contributes8% of total emissionsnationally
• These contributionsvary with devolvedauthority
• The agriculturalcontribution isassessed by a tier 1methodology
2DECC 2009
2050 targets for GHGs
DEFRA 2009
-77%
Electricity
Transport
Residential
Industry
Other CO2
Non CO2 GHGs
Aviation
20502006
695 Mt CO2e
184
103
30
98
42A compliance system of 5-yearcarbon budgets, set up to 15 yearsin advance
A 34% reduction required by 2018-2022
ConstraintsConstraints
• The need to producefood
• Emissions leakage• Climate• Economics• Technical constraints
4
Assessing mitigationpotentialAssessing mitigationpotential
• Evidence for mitigation potential of differentmeasures was taken from– Reviews of relevant literature– Output from models– Expert opinion
• The above approach was also used to provideinformation on uncertainty
5
0
5,000
10,000
15,000
20,000
2017 - Pessimistic 2017 - Optimistic 2022 - Pessimistic 2022 - Optimistic
Abatement achievable for <£100/t for categories of measures (private discount rate, new interactions method)
ktCO2e
Soil managementNitrification inhibitorsUsing more N eff. Plants
ADManure managementLivestock breeding
Diet manipulation
Nutrient management
Abatement potentialAbatement potential
6Source: MacLeod, M., Dominic Moran, Alistair McVittie, Bob Rees, Glyn Jones, David Harris, Steve Antony, Eileen Wall, Vera Eory, AndrewBarnes, James Jones, Kairsty Topp, Bruce Ball, and Steve Hoad and Lel Eory (2010) Review and update UK MACCs for agriculture and toassess abatement potential during the 4th budget period (2023-2027) Final report London: The Committee on Climate Change
Key features of theMitigation Abatement Cost Curve methodKey features of theMitigation Abatement Cost Curve method
• The system boundary was drawn at the farm-gate, potential life cycleeffects were noted but not integrated into the analysis
• Analysis limited to GHG effects, didn’t include wider ancillarycosts/benefits (e.g. water quality, animal health/welfare)
• Simplified modelling of interactions between mitigation measures• In order to reflect uncertainty in assumptions, 2 versions of the MACCs
were produced:
7
Optimistic MACC Pessimistic MACC
Higher estimate of area of applicability Lower estimate of area of applicability
Higher estimate of abatement rate Lower estimate of abatement rate
Lower estimate of cost Higher estimate of cost
Nutrient managementNutrient management
• N2O emissions aremore sensitive tofertiliser applicationrates than any otherfactor
• Careful adherence tobest practice andfertiliserrecommendations canreduce emissions
8
N application rate (kg ha-1)
Bouwman et al, 2002
Soil ManagementSoil Management
• Soil and climateinteract to modify N2Oemissions fromfertilisers
• Wet and mildconditions promotegreater emissions andjustify regionalemission factors ininventory calculations
9Flechard et al 2007
Soil structure and N2O and CO2emissionsSoil structure and N2O and CO2emissions
10Improving soil quality
DrainageDrainage
• Drainage has acomplex relationshipwith GHG emissions
• Improved drainagereduces N2Oemissions, butprobably increasesCO2 emissions andimproves cropproduction 0
1
2
3
Well drained Poorly drainedN
2Oem
issi
onkg
Nha
-1y-1
11Bouwman et al, 2002
TillageTillage
• Min till can providesmall increases on soilC
• These can be offset byincreased losses ofN2O
• Effects may be sitespecific
12Goulding et al 2004
Nitrification inhibitorsNitrification inhibitors
• Nitrification inhibitorscan be added tofertilisers to reduceN2O emissions
• The efficiency ofdifferent inhibitorsvaries
• They also responddifferently underdifferent fieldconditions
13
Relative N2O emission
Akiyama et al 2010
Using more efficient plantsUsing more efficient plants
• Existing crop varietiesvary in their N useefficiency
• This is probablyassociated withdifferences in N2Oemissions
• Screening and plantbreeding could exploitthis
14
Anaerobic digestionAnaerobic digestion
• Captures CH4 frommanure/slurry togenerate power and heat
• On-farm or centralisedusing additionalfeedstock e.g. foodwaste
• Digestate used as Nsource – potentialbiosecurity and wasteissues
15
Manure managementManure management
• Improved timing• Full allowance for
nutrient value• Avoidance of combined
applications of slurriesand manures
16
Livestock geneticimprovementLivestock geneticimprovement
• Genetic improvement is a tool that can beused to reduce emissions
• 3 modes of action– Breeding for improved efficiency of the animal
(indirect)– Breeding for improved efficiency of the system
(indirect)– Breeding for reduced GHG emissions (direct)
17
18
Genetic improvement inlivestockGenetic improvement inlivestock
• Selection on improved feedconversion efficiency canhelp to reduce emissions– Broilers reach 2 kg in 36
days(1999) vs 63 days(1976)
– Dutch Landrace: FCR is 2.8kg/kg (1990) vs. 3.5 (1930)
• Beneficial effect onreducing the emissions perunit of product
Jones et al., EAAP, 2008
Due to lowuptake ofimprovedgenetics
Animal nutrition/diet optionsAnimal nutrition/diet options
• Main target enteric methane from ruminantsimproving the efficiencies in utilising diet– Changing feed: better quality to improve efficiency of
feed utilisation (↑starch/rapid fermentable carbs)– Feed additives: help animal utilise energy or the way in
which the rumen works
19
– Targeting rumen bugs:impact on the rumenpopulation to controlmethane bugs
Soil C sequestrationSoil C sequestration
• Soils offer importantopportunities for Csequestration
• Often these areincluded with othermitigation methods e.g.manure and slurrymanagement
20
2121
Mitigation Abatement CostCurvesMitigation Abatement CostCurves
Building a low-carbon economy – The UK’s contribution totackling climate change. 1st Report of the CCC, Dec, 2008
Height = costeffectiveness
Width =abatementpotential
2222
Mitigation Abatement CostCurvesMitigation Abatement CostCurves
Building a low-carbon economy – The UK’s contribution totackling climate change. 1st Report of the CCC, Dec, 2008
Cheap option, bigemission savings
Expensive options,small emission savings
Financialsavings
23
ConclusionConclusion
• Agricultural landscapes are an important source ofgreenhouse gases in the UK
• Grasslands are a particularly important ofemissions of both N2O (soils) and CH4 (livestock)
• Manipulation of systems through managementoffers a major opportunity for mitigation
• We need more information on effectiveness ofmitigation methods and improved reportingsystems that will reflect actual emissions andmitigation
AcknowledgementsAcknowledgements
This work has been supported financially by:– Committee on Climate Change– Scottish Government
24