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:

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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

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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

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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

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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

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Manure managementManure management

• Improved timing• Full allowance for

nutrient value• Avoidance of combined

applications of slurriesand manures

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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)

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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

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– 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

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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

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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

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