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SID 5



Research Project Final Report
Note
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SID 5 (Rev. 3/06)
Project identification
AC0216
Review of the Marginal Abatement Cost Curves for
Agriculture produced for the Committee on Climate
Change
Contractor
organisation(s)
AEA
Gemini Building
Harwell
Oxfordshire
OX11 0QJ
54. Total Defra project costs
(agreed fixed price)
5. Project:
Page 1 of 25
£
19,404
start date ................
09 April 2009
end date .................
20 May 2009
6. It is Defra’s intention to publish this form.
Please confirm your agreement to do so. ................................................................................... YES
NO
(a) When preparing SID 5s contractors should bear in mind that Defra intends that they be made public. They
should be written in a clear and concise manner and represent a full account of the research project
which someone not closely associated with the project can follow.
Defra recognises that in a small minority of cases there may be information, such as intellectual property
or commercially confidential data, used in or generated by the research project, which should not be
disclosed. In these cases, such information should be detailed in a separate annex (not to be published)
so that the SID 5 can be placed in the public domain. Where it is impossible to complete the Final Report
without including references to any sensitive or confidential data, the information should be included and
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In all cases, reasons for withholding information must be fully in line with exemptions under the
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Executive Summary
7.
The executive summary must not exceed 2 sides in total of A4 and should be understandable to the
intelligent non-scientist. It should cover the main objectives, methods and findings of the research, together
with any other significant events and options for new work.
In this project, AEA critically reviewed the output from project RMP4950, carried out by SAC, (UK Marginal
Abatement Cost Curves for the Agriculture and Land Use, Land-Use Change and Forestry Sectors out to
2022, with Qualitative Analysis of Options to 2050). The remit for this project was to re-evaluate the inputs
for measures for which the unit abatement costs were <£26/t CO2-eqv. Project outputs were required to
inform discussions within Defra on feasible sector contributions to the GHG emission reduction targets set
out in the carbon budgets to 2022. The scope was broadened slightly to cover measures whose
abatement potential, applicability or costs may have been under-estimated.
The approach taken was to review the abatement potential and costs and provide quantitative estimates of
uncertainties, where appropriate, for individual mitigation methods that were estimated to be less than
£40/t CO2-eqv. in the SAC MACC report (including anaerobic digestion and land drainage). Capital,
annual running cost and annual income/benefit were reviewed and incorporated. Capital costs included
anticipated total initial expenditure not calculated per unit (unless stated as per unit). Annual costs
included annual management/use costs (including allowance for depreciation and finance of capital
investment) calculated per unit. Annual income/benefit = estimated annual financial benefit of
implementation of abatement measure (if applicable) calculated per unit. The review was to establish if
the figures were correct on average and state the level of uncertainty (quantitatively).
Each measure was reviewed with respect to the abatement potential and assumptions used by SAC.
Where new studies or sources of information provide the ability to make an improved estimate of
abatement potential, the SAC figure was revised. In this preliminary exercise we were not able to re-run
the SAC-MACC model. Instead we took the reported output from the final report and applied adjustment
factors to re-calculate the potential for emission reductions. We have used the reported central feasible
potential (CFP) obtained from tables E.1 (2022) from the SAC final report.
The AEA estimate of potential abatement in 2022 at c. 3777, t CO2-eqv. is c. 48% of that of the SAC
output, with a range equivalent to c. 21-117% of the SAC CFP. SAC note that, without exception, the AEA
“mean” estimates are equal to or less than the SAC estimates. It is also worth noting that most (55%) of
the discrepancy between the SAC and AEA estimates is down to differences on three measures: beef and
dairy ionophores and mineral N timing. On these three measures, AEA have adopted conservative
assumptions regarding the “mean” abatement”, i.e. that it would be 0. The maximum estimate largely
arises as a result of using the greater end of the range of reduction considered possible for improved
manure N timing applied in livestock manures.
SID 5 (Rev. 3/06)
Page 2 of 25
With respect to beef and dairy ionophores AEA took their mean abatement to be 0 since the use of those
supplements is currently banned in the EU. With respect to the efficacy of timing mineral N applications
AEA interpreted the technique to be effective as described in the SAC report, i.e. to reduce demand for
total mineral-N application by applying fertilizers at the most responsive time. Since this is already
standard practice there appears to be no further scope for increasing crop yield/reducing fertilizer-N
requirement in this way. However, it appears that SAC had meant the term to mean applying fertilizer-N at
times that have been shown in experiments to minimise emissions of N 2O. However, such a measure
would not bring any yield benefits or cost savings as had been assumed.
Using the SAC cost estimates with the range of abatement/applicability potential proposed by AEA, the
potential saving from implementing measures with an abatement cost of < £26 t CO 2-eqv. ranges from c.
£84 M (11% of SAC estimate) to £1402 M (*2 the SAC estimate) with a mean of £128 M (17% of the SAC
estimate). However, caution needs to be exercised with respect to these results. First, they are based on
SAC cost estimates which our review suggests may need adjusting. Second, much of the potential
savings in the maximum estimate arise from the use of ionophores which are currently not allowed.
Abatement potential between England and UK was apportioned by weighting the abatement estimated for
each measure by the proportion of the relevant sector in England. Using this approach c. 67% of the
potential for GHG abatement arises from agriculture within England
SID 5 (Rev. 3/06)
Page 3 of 25
Project Report to Defra
8.
As a guide this report should be no longer than 20 sides of A4. This report is to provide Defra with
details of the outputs of the research project for internal purposes; to meet the terms of the contract; and
to allow Defra to publish details of the outputs to meet Environmental Information Regulation or
Freedom of Information obligations. This short report to Defra does not preclude contractors from also
seeking to publish a full, formal scientific report/paper in an appropriate scientific or other
journal/publication. Indeed, Defra actively encourages such publications as part of the contract terms.
The report to Defra should include:
 the scientific objectives as set out in the contract;
 the extent to which the objectives set out in the contract have been met;
 details of methods used and the results obtained, including statistical analysis (if appropriate);
 a discussion of the results and their reliability;
 the main implications of the findings;
 possible future work; and
 any action resulting from the research (e.g. IP, Knowledge Transfer).
SID 5 (Rev. 3/06)
Page 4 of 25
Defra project AC0216 – Project Report
Analysis of the SAC MACC report to inform discussions on setting contributions to Carbon
budgets
1. REASONS FOR THE STUDY
The purpose of this study was to review the Marginal Abatement Cost Curves produced by the Scottish
Agricultural College in the SAC MACC report 1, by reviewing the assumptions made in their development
in order to estimate likely cumulative savings in GHG emissions using a methodology consistent with
that used by SAC. The outputs from this project were required to inform discussions within Defra on
feasible contribution from the agricultural sector towards the GHG emission reduction targets set for the
first three carbon budgets (to 2022).
2. SCIENTIFIC OBJECTIVES
The measures identified in the SAC-MACC for which the abatement costs were estimated to be <£40 t
CO2-eqv. were investigated. While the remit for this project was to re-evaluate the inputs for measures
for which the unit abatement costs were <£26, we broadened the scope slightly to cover measures
whose abatement potential, applicability or costs may have been under-estimated.
Analysis was carried out to:
1.
Review the reliability of the costs for options identified in the report as having an abatement cost
below £40/t and establish if the figures are correct on average for a significant proportion of
potential abatement. If not, the level of uncertainty was quantified.
2.
For the zero, negative and low cost options (i.e. up to and including AD and drainage):

We reviewed the SAC assumptions to provide revised estimates of the abatement potential
under each method. The level of uncertainty (ranges) around these estimates was made.

Where appropriate, we provided revised estimates of the abatement potential for each
mitigation option below £40/t, providing a view of the extent to which this estimate should be
refined with reference to the caveats in the SAC report.
Cumulative abatement potential for these methods.
We calculated interim cumulative savings in GHG emissions using a methodology that would deliver
comparable results to that used by SAC in the SAC MACC report.
SAC were subcontracted to use the data from the above outputs to estimate the cumulative and
maximum technical potential abatement, with ranges and an assessment of uncertainty, that can be
delivered by 2022.
North Wyke Research (NWR) were contacted to provide comments on how the mitigation measures
could be captured in the inventory, including feasibility and timescale. However, due to ongoing
commitments at NWR and the extremely short timescale of this work, no comments were received.
1
UK Marginal Abatement Cost Curves for the Agriculture and Land Use, Land-Use Change and
Forestry Sectors out to 2022, with Qualitative Analysis of Options to 2050, carried out by the Scottish
Agricultural College for the Committee for Climate Change – SAC MACC (project RMP4950).
SID 5 (Rev. 3/06)
Page 5 of 25
3. METHODS
Introduction
Abatement cost curves are produced to rank abatement measures in order of their cost-effectiveness.
To do this information needs to be entered to the model to quantify:

the abatement potential, usually expressed as a % of the unabated emission, by which the
emission from the source will be reduced;

the applicability of the potential measure, usually expressed as a % of the source to which the
measure may be effectively applied;

the input cost of the measure, the cost to the operator of the source of implementing the
measure expressed for agricultural abatement, as £ per hectare, per livestock place or some
other recognised unit.
In the SAC model abatement potential (AP) is an output, not an input, calculated using the measures
abatement rate, area of application and rate of adoption. Hence the abatement per unit area is the
abatement rate, and the total mass of CO 2e abated over a defined area and time period as the AP. The
remit of this project required AEA to provide realistic assessments of all the above. However, in some
cases, for example when the measure involves a change of management, the efficiency and
applicability are inextricably linked and clearly there may be uncertainties in this and so we also provide
the smallest and greatest estimates of realistic abatement and or applicability that have been reported.
Abatement potential
Abatement potential ought to be the easiest to quantify and to provide reliable estimates of uncertainty.
In many cases replicated experiments will have been conducted, some in experimental facilities some
on commercial farms, and hence both a mean and standard error (SE) should be available for both the
unabated and abated emission. However, for many of the potential measures which were input to the
cost curve, relatively few experiment have been carried out and even fewer have been conducted on
commercial farms. It should also be made clear that uncertainties associated with individual field
experiments cannot simply be translated into a national uncertainty value. In addition, the nature of
some of these measures involves changes to farm management rather than the application of some
'end-of-pipe' technology and hence experiments to verify the efficacy of such approaches are costly and
difficult to replicate. For example, increasing the ratio of silage maize to that of grass maize in ruminant
diets has been shown to reduce total N excretion by the livestock and this in turn will reduce emissions
of N2O when that excreta is returned to land. This is because the protein and N concentration of maize
silage is less than that of grass silage for equivalent amounts of energy intake. However, the extent to
which N excretion will be reduced will depend upon the quality and N concentration of the maize silage
that is to be introduced and the quality and N concentration of the grass silage that is to be replaced.
The N concentrations of both types of silage will vary among farms and among seasons. While a fairly
robust average reduction in N excretion and consequent N 2O emissions can be reported, to quantify the
uncertainty is more difficult due to the relative lack of comparisons within and among farms and years.
For some of the measures therefore, the uncertainty of the abatement potential will be large due to a
lack of empirical data.
Evaluation of the SAC-MACC output was complicated by the fact that the abatement
efficiencies were not based on % reduction emissions from a source but on the measure’s abatement
rate estimated by SAC in the form of t CO 2-eqv./ha/y. This means of expressing abatement lessened
the transparency of the output available, as it is less clear how the figures were obtained.
Application potential
Several of the abatement measures evaluated by SAC were changes to management practices that
reduce emissions by changing the amount or type of input, as opposed to abatement techniques that
act by preventing or capturing GHG emissions. So comparison could be made of potential applicability.
Application potential will tend to be more uncertain, and often much more uncertain than the
effectiveness of abatement options. This tends to also increase with management measures compared
with technical measures. This can be illustrated with reference to livestock manures. While a
reasonably robust estimate may be made of potential reductions in N2O emissions from making a full
allowance for the N supplied in manures when deciding on the amounts of fertilizer-N to apply to a crop,
there is considerable uncertainty over the extent to which farmers are already making such an
allowance. This particular issue is discussed in more detail below. But, in short, if asked almost all
farmers would probably say they are already doing this (of course this should not be assumed to mean
they are). However, their knowledge and understanding of manure-N availability will vary enormously.
SID 5 (Rev. 3/06)
Page 6 of 25
Implementation costs
Implementation costs of abatement within the MACC have the greatest inherent uncertainty. This
applies especially to measures that have not been implemented on commercial farms to date and to
management measures, some of which are difficult to cost without making assumptions. For example,
the proposed option of applying manures as litter-based farmyard manures (FYM) will, on farms with
slatted floors to collect excreta as liquid slurry, require the installation of solid floors to farm buildings,
while on farms with buildings that already have solid floors the additional cost may be limited to the
purchase of straw. For farms on which all manure is currently handled as slurry a solid manure
spreader will need to be purchased, while on farms which manage manure as both slurry and FYM
additional machinery will not be needed but the greater labour cost of handling solid manure will need to
be taken into account. Hence for this measure, due to the range of different circumstances likely to be
found on farms, the likely range of costs will be considerable over and above the inherent uncertainties
of estimating those costs. It is important to note in the SAC_MACC report that SAC had assumed there
would be no additional costs associated with this measure. In our discussions during the course of the
project reported here SAC agree that there may be some additional costs that need to be considered
here. Further detailed analysis is likely to be required to properly assess the impacts of individual
mitigation measures.
3.1. Approach used
Task 1 Review of abatement options
The approach taken was to review the abatement potential and costs and provide quantitative estimates
of uncertainties where appropriate for individual mitigation methods that were less than £40/t in the SAC
MACC report (including anaerobic digestion and land drainage).
Capital, annual running cost and annual income/benefit were reviewed and incorporated. Capital costs
included anticipated total initial expenditure. Such costs were not re-calculated on a per unit basis (i.e.
per pig place etc.) unless the costs presented by SAC were stated as being per unit. Annual costs
included annual management/use costs (including allowance for depreciation and finance of capital
investment) were calculated per unit. Annual income/benefit = estimated annual financial benefit of
implementation of abatement measure (if applicable) was calculated per unit.
The objective was to review the figures reported in the SAC MACC and assess their level of uncertainty
(quantitatively).
Tasks 2a, b and c Assessment of potential of measures to reduce emissions
Each measure was reviewed with respect to the abatement potential and assumptions used by SAC.
Where new studies or sources of information provide the ability to make an improved estimate of
abatement potential, the SAC figure was revised.
In this preliminary exercise we were not able to re-run the SAC-MACC model. Instead we took the
reported output from the final report (Moran et al., 2009) and applied adjustment factors to re-calculate
the potential for emission reductions. In all cases we have used the reported central feasible potential
(CFP) obtained from tables E.1 (2022) as the basis of our calculations. Our estimates of the minimum
and maximum were derived from the reported CFP adjusted by our own estimates of abatement
potential and likely applicability. In this report we consider abatement potential for 2022.
Re-estimation of emission potential
We re-calculated the abatement potential by multiplying the estimate made by the SAC model by the
abatement efficiency/applicability coefficient that we had derived from an earlier study, and divided the
result by the abatement efficiency/applicability coefficient reported by SAC. Using the measure AE
(Crops-Full-Manure) as an example, for which the abatement potential was reported to be 457.26 t CO 2eqv. in table E.1, we multiplied the output by our estimate of the potential for this measure (a 2%
reduction in fertilizer-N use), and divided by the SAC estimate of the potential for this measure in 2022
(7.7% actual reduction in fertilizer-N use/emissions due to interactions). Hence the calculation was:
457.26 * 2.0/7.7 = 118.77 t CO2-eqv.
Hence this approach maintained the overall assumptions (e.g. business as usual (BAU)) and structure.
Re-estimation of costs per t CO2-eqv. abated
In the preliminary work, we maintained the estimates of input costs used by SAC. But, since for many
measures our estimate of potential abatement was different to the estimate made by SAC, even using
common cost assessments, differences in estimated unit costs of abatement may arise. However,
whether this happens or not depends upon whether the measure was a technical measure, for which
SID 5 (Rev. 3/06)
Page 7 of 25
our estimate of abatement efficiency differed, or a management measure for which our estimate of the
applicability differed.
Technical measures
An example of a technical measure would be the improvement in field drainage (AC, Crops-Soilsdrainage) which SAC estimated could lead to a 10% reduction in emissions of N 2O while we considered
a more conservative estimate of a 5% reduction to be more likely. However, regardless of the assumed
efficacy, the same area of land would need to be drained and hence the total cost of the measure would
remain unchanged. Under AEA interpretation of the SAC-MACC output, if the abatement efficiency is
only half that used in the SAC model then the cost per t CO 2-eqv. would double from £14.44 to £28.88
per t CO2-eqv. However, the way the SAC-MACC is configured a reduced AP would not necessarily
lead to a change in CFP. In the case of measures that have potential to improve productivity and hence
to increase income, where we consider the efficiency to be less than that used by SAC then the savings
per t CO2-eqv. will be less. Nevertheless, the total cost (or savings in the case of cost-negative
measures) would be unchanged.
Management measures
In the case of measures such as AE, making full allowance for the N in manures, we consider that it is
the potential for applying this measure that is less than that used by SAC, not the efficiency of the
measure (see the section on Full manure-N allowance below for an explanation of this conclusion).
Hence in such cases there will be no change to the costs (or savings) per t CO 2-eqv. abated, but the
total costs (or savings) will be less because the measure will be adopted to a lesser extent. This is also
seen in the SAC output when comparing CFP and MTP, since the latter was based on a greater uptake
of measures the costs (or savings) per t CO 2-eqv. abated were often the same for both scenarios (the
exceptions were the measures adopting anaerobic digestion (AD). This comment was agreed by SAC.
Estimate of cumulative costs
As explained above, our estimates of the total costs (or savings) of management measures will change,
while those of technical measures may not. In this exercise we simply summed our estimates for each
measure to produce an estimate of cumulative costs. This approach was agreed by SAC.
Input costs (costs to the farmer of implementing the measure)
Revision of the costs, using our estimates of input costs, could only be done using the same approach
as outlined above for recalculating emissions.
Task 2d and e Assessment of input costs, i.e. costs to farmers to implement measures
Draft figures of abatement potentials and cost per tonne of carbon for each mitigation option were to be
reported by 16 April, including an interim assessment estimate of what the SAC
SID 5 (Rev. 3/06)
Page 8 of 25
4. RESULTS
4.1. Task 1 review the abatement potential and costs and provide quantitative estimates
Table 1 below lists the measures identified by the SAC MACC for which the abatement costs were
estimated to be <£40 t CO2-eqv. While the remit for this project is to re-evaluate the inputs for
measures for which the unit abatement costs were < £26, we thought it wise to broaden the scope to
cover measures whose abatement potential, applicability or costs may have been under-estimated.
Table 1. SAC-MACC estimates of the central feasible potential scenario for abatement
and the costs per t CO2-eqv. abated. (Negative costs indicate the technique would be
profitable to introduce).
Measure
Beef Ionophores
Beef improved genetics
Soils mineral-N timing
Soils manure-N timing
Soils full manure-N allowance
Soils reduced tillage
Dairy improved productivity
Dairy Ionophores
Dairy improved fertility
Soils improved N use plants
Dairy maize silage
Soils avoid N excess
Soils used FYM/composts
Soils delay mineral-N /slurry
OFAD Pigs large
OFAD Beef large
OFAD Pigs medium
OFAD Dairy large
CAD Poultry
Soils improved drainage
OFAD beef medium
OFAD dairy medium
2012
Amount
Cost
abated, kt
effectiveness £
CO2-eqv.
/t CO2-eqv.
103.39
-1384
4.60
-2874
192.50
-94
158.01
-49
388.53
-125
2.58
6744
41.82
0
215.77
-50
33.38
0
101.76
-30
27.99
-270
85.68
-24
43.85
0
12.57
0
14.18
7
27.47
3
4.77
12
64.19
14
61.36
9
443.17
42
15.56
18
20.76
26
2022
Amount
Cost
abated, kt
effectiveness £
CO2-eqv.
/t CO2-eqv.
347.38
-1748
46.32
-3603
1150.39
-103
1027.16
-68
457.26
-149
55.77
-1053
377.36
0
739.36
-49
346.26
0
331.80
-76
95.98
-263
276.06
-50
78.51
0
47.17
0
47.77
1
97.79
2.5
16.06
5
250.81
8
219.34
11
1741.02
14
50.77
17
44.12
24
2. Potential of measures to reduce emissions
The measures included in the SAC-MACC are grouped under three themes, rather than listed in the
order they appear above. The themes are soils/crops/fertilizers, enteric fermentation and manures.
For some measures, such as improved timing of manures and N fertilizers, the abatement efficiency
and the applicability are inseparable and hence for all potential measures abatement efficiency and
applicability are discussed together. The potentials for abatement and applicability reported below, and
summarised in table 2, relate to implementation by 2022.
Soils/crops/fertilizers,
Improved mineral-N timing
The SAC report indicated that improved mineral-N timing could lead to a 3-5% increase in yield and
hence reduce emissions of N2O by 3-5% as a result of reducing the amount of N needed to produce a
given amount of crop. However, a large body of existing data shows crop yields are not sensitive to
nuances in timing. In response to claims made that precise timing of fertilizer-N application was needed
to ensure optimum yield, ADAS carried out a large number of field experiments to investigate these
claims. Results showed that within fairly broad guidelines timing of fertilizer-N was far less important
than applying the appropriate amount to optimize crop yields. However, much of these data remain
unpublished. Advisory experience suggests that farmers apply N fertilizer at the times recommended by
systems such as PLANET, hence we concluded that there is no further scope for reducing emissions of
N2O by this means. The upper range for potential abatement could be regarded as the 5% quoted by
SAC. However, in this revision we have not assigned a range of potential efficiencies for this measure
as the evidence seems clear that there is no further potential for yield improvements from timing of
fertilizer-N application.
Improved manure-N timing
The SAC report suggested that improved manure-N timing would be effective by the same mechanism
as that given above. We agree that there is scope to improve effectiveness of manure-N by better
timing, but this is not easy to quantify. For example, manures are often applied in late summer and
SID 5 (Rev. 3/06)
Page 9 of 25
early autumn before planting arable crops. However, most, if not all, of the available-N in such manures
may be lost by leaching over winter. It is currently a requirement in NVZs not to apply slurries or poultry
manures to soils with a high risk of leaching at these times. However, opportunities to apply all
manures in spring, when the available-N will be recovered more efficiently, are limited and may conflict
with measures to reduce emissions of NH3. We agree with the 4% abatement potential proposed by
SAC. The range would be that cited in the Defra report by IGER and ADAS (AC0206) i.e. 2-10%. This
measure was acknowledged to be of high uncertainty in the SAC report. SAC were happy with this
comment.
Full manure-N allowance
The AEA assessment of this measure for the EA, made using data reported by the British Survey of
Fertilizer Practice (BSFP) suggested the potential for this measure is nearer to 2% than the 15% used
by SAC. The report for Defra project AC0206 (Agriculture and climate change: turning results into
practical action to reduce greenhouse gas emissions - A review) suggested there was potential to
reduce fertilizer-N use by 5% by making better allowance for manure-N. We consider this measure
cannot exceed a reduction of 11% of fertilizer-N applications, since the total amount of readily-available
manure-N applied to land, as estimated by the NARSES model (Webb and Misselbrook, 2004), is only
c. 11% of the amount of fertilizer-N currently applied. SAC make the point that readily available manure
N at the time of application is not the only driver of N 2O emissions since mineralisation and subsequent
nitrification/denitrification are likely to be significant (Jones et al. 2007). AEA agree with this statement.
However, on p 26 and elsewhere on the SAC MACC report it is stated that the effectiveness of this
measure is via reducing the total amount of N applied. This will only be done with respect to readilyavailable N which is what is taken up by the crop. If fertilizer-N applications are reduced to make
allowance for the total manure-N applied this will have costs since yield will be reduced. Hence the
range of potential abatement may be taken to be 2-11%. This measure was acknowledged to be of
high uncertainty in the SAC report.
Reduced tillage
Reduced tillage, unless the reduction is a consequence of replacing annual cropping with perennial
cropping, is now considered to often have no net impact on total C storage but to change the distribution
of soil organic carbon (SOC) in soils, leading to a greater proportion in the surface horizon (Baker et al.,
2007: Gal et al. 2007). This was also the conclusion of Defra project AC0206, which pointed out that in
the UK long-term reduced tillage is impractical as cultivation needs to be carried out every 3-4 years to
avoid the build-up of grass weeds. There will be some savings in fuel consumption resulting from
reduced tillage compared with using the plough, but this GHG reduction due reduction in fuel use may
to some extent be balanced due to increased fuel use from the greater number of herbicide spraying
operations needed to control weeds and the GHG emissions arising from production of those pesticides.
The SAC-MACC omitted CO2 emissions from energy use so will not be considered here. The range of
efficacy for reduced tillage is from 0 (our assessment) to that used by SAC. We agree with SAC that
the range of values indicated in the SAC report and in the AEA critique represent the uncertainties of
this measure.
Avoid N excess
The SAC report assume fertilizer-N use can be reduced by 10%, so that applications do not exceed the
recommended optimum, without reducing yield. Project AC0206 suggested a 5% reduction might be
feasible, while our assessment of the BSFP data indicated a 1% reduction might be more appropriate.
Hence the range of abatement potential varies from 1 to 10%. SAC agreed with this range of potential
reductions.
Use FYM/composts instead of slurries
The AC0206 study recommended the converse, to that of the SAC report, suggesting that FYM should
be replaced with slurry systems, to reduce GHG emissions from livestock manures. More recent work
by AEA and Cranfield University (Defra project AC0208) indicate that overall GHG emissions may be
reduced slightly by adopting one method of manure management over the other, albeit results were
different for pigs and cattle. We conclude that data from studies specifically comparing GHG emissions
from slurry- and FYM-based systems are too few and too inconsistent to recommend one form of
manure over the other. For this proposed measure the range will be the maximum set at the abatement
considered possible by SAC (5%) while the lower end of the range will be a 15% increase in GHG
emissions as suggested by AC0206 (who suggested changing from FYM to slurry might reduced GHG
emissions by 15%). SAC commented that their own research however does suggest fewer emissions
from slurries that manures containing comparable amounts of N (Jones et al., 2004; Jones et al., 2007)',
which seems to concur with the conclusion from AC0206 and runs counter to the measure proposed in
the cost curve to 'use composts, straw-based manures in preference to slurry' (p23).
SID 5 (Rev. 3/06)
Page 10 of 25
Delay application of mineral-N when applied to same crop as slurry
Applying fertilizer-N and slurry at same time has been shown to increase emissions of N 2O to more
than the sum of separate applications. Hence separating the application of the two materials by a few
days should lead to reduced emissions. The range of potential reductions appears to be between 2 and
5% (Stevens and Laughlin, 2001). In the SAC-MACC report the potential abatement of this measure is
5%.
Improved N use plants
Plant breeding makes improved N use potentially possible, but suitable varieties need to be bred. SAC
suggest this approach could lead to 30% less fertilizer-N being required by 2022. We consider this
over-optimistic and speculatively suggest that, should a breeding programme be initiated which begins
to deliver new varieties within 5 years, and that a 1% annual improvement in N fertilizer efficiency then
accrues each year, then perhaps a 9% reduction in N fertilizer use might be achieved by 2022. SAC
consider this to be a very conservative estimate but given that it can take from 5 to 7 years for new crop
varieties to reach the market and that crop response to N inputs is complex and subject to a number of
drivers AEA consider such a conservative estimate to be appropriate.
Improved soil drainage
On balance improved drainage should reduce emissions of N 2O, although on some soils, in some
seasons, emissions could increase. This approach is difficult to quantify. AEA proposed a more
modest reduction of 5%.
SAC point out that information on drainage indicates that this is important driver for N 2O
emissions. They consider the most comprehensive assessment of N 2O studies to date was carried out
by Bouwman. He showed that in over 600 comparisons that N 2O emissions from poorly drained soils
were about 10% higher than well drained soils (Bouwman et al. 2002). Work on the effect of soil water
table on N2O emissions was carried out by Smith and Dobbie (2002) in Scotland, showed a very
substantial fall in emissions with an increasing depth to water table, under a drained pasture. The
largest fluxes occurred when the soil water table was within 10 cm of the surface and other parameters
were not limiting. These results suggest that if the if drainage were improved, the annual flux could be
substantially reduced.
There does seem to be some debate on this issue. Improving land drainage may not axiomatically
reduce emissions of N2O, which are related to water-filled pore space (WFPS). There is a risk that on
the heavier, wetter soils, in which denitrification takes place but produces predominantly N 2, drainage
will reduce the WFPS to that optimum for production of N 2O. Stehfest and Bouwman (2006) did not
identify drainage status as a controlling factor for emissions from agricultural fields. For soils under
natural vegetation Stehfest and Bouwman found smaller emissions from poorly-drained soils. They
considered that, in general, poor drainage and high bulk density both limit gas diffusion. Under low gas
diffusivity N2O is more likely to be re-consumed before being emitted from the soil (Davidson, 1991). In
contrast, Rochette (2008), in an evaluation of the interaction between drainage status and tillage regime
on emissions of N2O reported greater emissions, under all tillage regimes, for poorly-drained soils.
SAC point out that there is considerable uncertainty regarding the present state of drainage
(and therefore the potential area over which it could be improved). Godwin et al (2008, p10) note that
land drainage has seen little reinvestment since the mid-80s, and estimate that there could be 2m ha,
plus 50,000ha x 20 years = 3m ha requiring improvement. The AP of drainage in the central feasible
potential MACC assumes improving drainage on 1.86m ha, which is consistent with Godwin et al.
(2008).
Enteric fermentation
Beef and dairy ionophores
The science is well established (with perhaps a few questions about persistency remaining) in relation
to the use of beef and dairy ionophores. But since ionophore use in feed is banned in EU then there is
no potential. If the ban was lifted these would have an immediate impact. In recognition that the
purpose of the MACC was to identify additional potential abatement, not abatement that will be
achieved under BAU conditions, AEA have taken the abatement potential, and applicability, as 0%, but
with a range of 0-25% in the event of the ban being lifted.
Dairy improved productivity and fertility
Potential breeding for production/fertility could achieve reductions in GHG emissions similar to those
proposed by SAC. There is also some suggestion that we can breed for reduced CH 4 emissions. But, if
the deadline is 2022 then that is likely too short a time horizon for an impact. In recognition that the
purpose of the MACC was to identify additional potential abatement, not abatement that will be
achieved under BAU conditions, AEA have taken the abatement potential, and applicability, as 5%, but
with a range of 5-22.5%.
SID 5 (Rev. 3/06)
Page 11 of 25
Beef improved genetics
As with dairy, 2022 is too soon to have a major impact, but perhaps an abatement of 2.5%, the lower
end of the 2.5-7.5% proposed by SAC should be assumed.
SAC make the following observation. The abatement potential for genetic improvement of any sort
tends to be cumulative. Farmers can use different bulls each year and with the availability of genetic
improvement tools (delivered to the national dairy, beef and sheep populations and updated regularly)
the males (and females) will improve year on year (i.e., the genetic merit of a bull 20 years ago is
different to the genetic potential of a bull today). The increased abatement potential of 15% in 2022 is
based on this continued genetic improvement of animals over time (i.e., 10 years of improvement from
2012 to 2022) and does not include breeding directly for reduced emissions which is likely to enhance
the abatement potential. This annual abatement rate of GHG emissions by continuing current selection
policies has been shown in the study of Jones et al. (2008) and the Defra report AC0204. The
abatement rate for selecting on fertility has been shown by Wall et al. (2009, in print) and Garnsworthy
(Animal Feed Science and Technology, 2004). However ,the impact of genetic improvement in beef
cattle and sheep has a far lower penetration rate and the best genetics do not disseminate through all
strata of the livestock population. Here we have taken a rate of uptake by the beef industry greater than
than assumed under BAU.
Dairy maize silage
The maize area may continue to expand due to climate change/plant breeding. So whilst the science
behind this mitigation strategy will not change significantly, the potential application could increase.
Potential abatement efficiency, through an increase in milk production per cow which is greater than the
increase in CH4 per cow, hence reducing CH4 emissions per L of milk, which equates to a reduction in
emissions of 5%, seems reasonable. This estimate was based on the proportion of grass: maize silage
in the diet reaching 3:1 compared with the current 1:3. A change of this magnitude is greater than
expected from BAU.
Manures
Anaerobic digestion
Uptakes were set at 30, 45 and 75% for the low, central and high feasibility potential scenarios
respectively have been used as with this measure the uncertainty is not over the abatement efficiency
but over the extent to which it might be adopted.
Table 2. AEA and ASRG estimates of the potential abatement efficiencies of the
measures identified as being most cost-effective by the SAC-MACC
Measure
Beef Ionophores
Beef improved genetics
Soils mineral-N timing
Soils manure-N timing
Soils full manure-N allowance
Soils reduced tillage
Dairy improved productivity
Dairy Ionophores
Dairy improved fertility
Soils improved N use plants
Dairy maize silage
Soils avoid N excess
Soils used FYM/composts
Soils delay mineral-N /slurry
OFAD Pigs large
OFAD Beef large
OFAD Pigs medium
OFAD Dairy large
CAD Poultry
Soils improved drainage
OFAD beef medium
OFAD dairy medium
AEA/ASRG
0
2.5
0
4
2
0
5
0
3
10
5
1
0
5
**3
**3
**3
**3
**3
5
**3
**3
Range
0-25
2.5-7.5
0
2-10
2-11
0
5-22.5
0-30
3-11.5
5-30
5
1-10
+15-5
2-10
**5
**5
**5
**5
**5
5-10
**5
**5
SAC input
25
5
3-5
3-5
*15
0.15 t CO2 eq/yr
15
30
7
30
5
10
5
5
**8
**8
**8
**8
**8
10
**8
**8
*this is the maximum efficiency used to calculate emissions in 2017. The potential is
considered to reduce presumably as a result of the measure becoming standard farm
practice.
**our ranges for the applicability of AD are the upper, central and lower feasible
estimates used by SAC.
SID 5 (Rev. 3/06)
Page 12 of 25
SID 5 (Rev. 3/06)
Page 13 of 25
Assessment of input costs, i.e. costs to farmers to implement measures
Table 3 below summarizes our assessments of costs in comparison with those reported by SAC.
Table 3. Re-appraisal of the potential costs of the measures identified as being most costeffective by the SAC-MAC Annex B5. The large number of decimal places is cited directly from
the SAC report.
Measure
AC0216 cost estimate
Beef Ionophores
Beef improved genetics
Soils mineral-N timing
£0.98/hd/yr
£16.59/beef cow/yr
£12.38/ha/yr
Soils manure-N timing
Potential capital cost of
£35-50 per m3 or £250 per
cow
Capital, £400.
£12.38/ha/yr
£57,000 capital, annual
costs, £58.
£54/cow/yr
Soils full manure-N
allowance
Soils reduced tillage
Dairy improved
productivity
Dairy Ionophores
Dairy improved fertility
Soils improved N use
plants
Dairy maize silage
Soils avoid N excess
Soils used
FYM/composts
Soils delay mineral-N
/slurry
OFAD Pigs large
AC0216 benefit
estimate
£6.80/hd/yr
£31/beef cow/yr
£38.45
£22.59/cow/yr
£5-37/ha
£111/ha
£58.80
£46-263/cow/yr
£46/ha saving in
fertilizer
£89-146/cow/yr
£89/cow/yr
£0-12.75
Capital, £0-396,000 (large
pig finishing unit). Annual
cost £7-397/hd.
£23-28/ha
None
None
SAC cost or benefit
estimate
£6.621803/hd/year
Assumed to be 0
No cost, yield increase (cost)
No cost, yield increase (cost)
Reduce N fertilizer cost by
15%
Sig. investment cost,
reduced running cost 16%
No cost
£6.621803/hd/year
No cost
One-off costs assumed to
be 0; no recurring costs
-£6.18679/hd/year
Reduce N fertilizer cost by
10%
Assumed no significant
cost
Assumed no significant
cost
*FEC services, 2003
Capital, £470,000,
£32.19/pig place
Annual, £15.82/pig pl
OFAD Beef large
Capital, £285,000,
£110.88/hd
FEC services, 2003
Annual, £73.44/hd
OFAD Pigs medium
Capital, £228,000,
£33.30/pig place
FEC services, 2003
Annual, £31.19/pig pl
OFAD Dairy large
Capital, £470,000,
£264.00/cow
FEC services, 2003
Annual, £131.26/cow
CAD Poultry
Capital, £16,000,000,
£110.88/layer
FEC services, 2003
Annual, £5.58/layer
place
Soils improved
Capital Costs: £2,450£104.46/ha
£1850/ha + £50/ha/yr.
drainage
2,950/ ha
+10% yld
Annual:£246.00-286.00
OFAD beef medium
Capital, £61,000,
£110.88/hd
FEC services, 2003
Annual, £212.19/hd
OFAD dairy medium
Capital, £228,000,
£336.03/cow
FEC services, 2003
Annual, £314.73/cow
*SAC do not cite the costs in their report, only the reference cited here. We have looked at the FEC
document but it would be conjecture to cite costs from that report as those used by SAC
It should be noted that: (a) SAC costs were obtained by linear programming (the foundation of a set of
practical optimising techniques known as mathematical programming methods) output and (b) the
revised cost assumptions will change the order measures are implemented in, and therefore their AP
and CE.
Ionophores
The cost estimates reported here suggest a much smaller input cost for beef than that used by SAC,
and also indicate a potential net benefit from increased productivity, consistent with the SAC-MACC
output. For dairy our much greater cost is largely due to implications for milk quality of using ionophores
which will reduce returns per litre (L), albeit production should increase.
Beef improved genetics
SAC assumed there would be no input cost. However, we considered there would be a cost for using
improved breeding stock. The mean cost of an ‘average’ bull across the four prime beef breeds
(Simmental, Limousin, Charolais and Aberdeen Angus) in 2009 is £3,397 (the British Livestock Genetics
Consortium – Bull Price Performance Index). The mean costs across the four breeds for a top 10% bull
is £4,435 and top 1% £5,719. Therefore the annual cost difference between (when using live bulls)
SID 5 (Rev. 3/06)
Page 14 of 25
average bulls and bulls in the top 1% is £16.59 per beef cow (based on 1 bull per 35 breeding cows and
an average working life of 4 years. The benefits outweigh the cost, so an overall negative cost is
confirmed. This was considered a fair representation of the difference between costs of Top bulls by
SAC.
Improved N timing
The cost of improved N timing was estimated from the cost of sampling and analysis of soil for mineralN content as a potential means of improving the timing of fertilizer-N application. However, this may not
be appropriate as mineral-N sampling is usually done to improve the accuracy with which the amount of
N to be applied is to be estimated rather than the timing. With respect to improving the timing of
manure application there may be a need for additional storage, on some farms at least, which would
need to be taken into account. AEA were not able to make any estimate of increased costs for storage
in the re-estimate of abatement potential.
Soils full manure-N allowance
To accurately estimate the available-N in manures could require the capital purchase of a Manure N
testing system (Quantofix N Meter). And for this measure soil mineral-N analysis might also be
appropriate.
Soils reduced tillage
Reduced tillage cultivation systems, if not already practised, are likely to require significant investment
costs. Capital costs depend on minimum- or no-tillage systems and size of equipment employed.
Costs range from £37,200 for combi-drill and cultivator to £72,000 for direct drill. We have assumed an
average investment of £57,000 for min/no tillage system. Additional annual costs assumed an
additional 1 or 2 spray passes of general herbicide. However, there will also be cost saving estimated
to be £111/ha/yr.
Dairy improved productivity
Again, we consider that there will be a cost to access superior breeding material. Assuming this
measure achieves an annual increase in yield of between 2.5% and 3.5% the annual benefit range
between low production (5,500 litres per lactation) and very high production (9,000 litres per lactation) is
£35.75-£81.90 per dairy cow per annum/lactation (if calving interval is >than 365 days). Hence this has
the potential to be cost effective, but would depend upon current levels of production. Since average
milk yields are currently around 7000 L/cow/yr, the benefits may be in the middle of the range reported,
and hence not much greater than the costs. SAC acknowledge these cost estimates to be reasonable, and point out
that there would also be a benefit to the farmer of adopting the current genetic improvement options
compared to selection on old breeding goals or random selection of bulls.
SAC responded to point out that Stott et al. (2008) showed that selection on the then national breeding
goal for dairy animals in the UK (production and fitness traits) would result in additional profit or
approximately £7 per cows per year compared with random bull selection. Such figures have also been
estimated for the current breeding goal (DairyCo Report 2007). This was not included in the MACC cost
benefits (there would have been proportion of double counting if included in it’s entirety) and therefore
genetic improvement is likely to be more beneficial and cost effective as an abatement option than
estimated.
Dairy improved fertility
We estimate there will be labour and veterinary costs to improve fertility. Labour cost of £5.30 per cow
for additional heat detection and additional veterinary input for routine fertility visits cost £17.29 per cow.
We have assumed there is no additional cost for varying herd nutrition through lactation.
This option was costed by SAC as having 0 costs as it is based on changing the breeding objective from
the current objective to one that may slow down the rate of improvement in milk production but begin to
turn around the genetic decline seen in fertility. This means, that farmer just changes bull selection from
one type of bull to another and cost differential between straws of semen should be negligible. This has
been shown to be possible, theoretically, and not reduce milk output (although does slow down the rate
of improvement in that trait) (Wall et al., 2009). There is no additional management intervention and
therefore costs in this option as it was modelled in the SAC MACC. However, using fertility
management, either alone or in combination with this option, would also have an effect but obviously not
be as cost-effective as there are on-going intervention costs. As with selection for improved productivity
there are additional benefits of selection animals based on genetic merit in that this is more profitable
than random selection of bulls.
SID 5 (Rev. 3/06)
Page 15 of 25
Soils Improved N use plants
Currently new/improved varieties are generally sold at a premium of 25%-30% over more established
(5-6 year old) varieties. Assuming a premium of 25% the additional cost over old varieties in the
following crops (pasture, pasture with clover, maize, winter wheat, oilseed rape and beans) ranges
between £5.00 and £37.00 per hectare with an average of £14.13 per hectare. SAC agreed these
points.
Dairy, increased use of maize silage
Dry matter yield of maize and medium intensity permanent pasture are relatively similar (12.0 t DM/ha
versus 11.6 t DM/ha). Therefore we have assumed there would not be additional land requirements for
this option. The cost for each crop including variable costs, growing costs and contractor charges is:
pasture, £35.60 per tonne DM; maize £68.18 per tonne DM. The greater costs for the cultivation of
maize include the costs of cultivation including any herbicides needed to control weeds in the ealry
period of maize growth. However, fertilizer costs are generally less for forage maize procduction than for
conserved grass. The BSFP cites average annual applications of N, P 2O5 and K2O of 41, 32 and 30
kg/ha respectively, compared with average annual applications of 96, 30 and 44 kg/ha respectively for
grass < 5 yrs. Therefore assuming 15 kg DM intake per day the additional cost of a 1:3 diet ratio over
3:1 is £0.2445 per cow per day or £89.24 per annum. This contrasts with the negative cost used by
SAC, albeit there is a potential net benefit. SAC consider that diet formulation, production etc can
change with time, circumstance and land availability. A full analysis of dietary changes that considers
full costs, both up and down the chain may have some benefit to understanding how and what we
should feed UK livestock in the future (across species, diets, regions and time). In this study no attempt
was made to assess the GHG emissions arising from tillage necessary for maize cultivation on soil
carbon. However, given the lesser requirement of forage maize for inputs of N, and the reduction in
GHG emissions arising from application, it is not axiomatic that net GHG emissions will be increased by
the conversion of pasture to tillage land in order to increase forage maize production. A full life-cycle
analysis is required to address this issue.
Soils avoid N excess
There may be no additional cost if fertilizer-N applications are based on freely-available sources such as
PLANET. However, most arable farmers are likely to be using such systems already. The potential
may exist on grassland farms, outside of NVZs on soils well-supplied with organic matter and with large
reserves of available-N. In such cases soil analysis for mineral-N would be useful but does imply some
additional cost.
Use of FYM/composts instead of slurry
If a solid manure spreader is needed (assumes farms have a front mounted loader) this could cost
between £5,000-£13,000. The introduction of solid flooring rather than slatted flooring was estimated to
cost £170-£210 per head. Additional FYM storage £55-£70 per head. In some cases no investment will
be required whereas some farms may require wholesale replacement of buildings. In the AEA
adjustment to the SAC-MACC output we were not able to make any estimate of the proportion assumed
to require investment as we had access only to the MACC output and not the input. Estimates of
additional labour to handle FYM over slurry range from <1 hour per day to several hours per day.
Standard labour unit used as cost of standard worker. Additional straw requirement can range from £0£26 per head.
Soils delay mineral-N /slurry
Annual costs are to repair soil damage e.g. compaction from the additional trafficking, and loss of yield.
Anaerobic digestion
Pigs, large
The costs were estimated for a unit comprising 3,445 finishers and a slurry/manure only system with a
capacity of 100 kW. Annual finance cost based on amortised capital investment. Returns based on
electricity and ROC prices as at 2009 i.e. wholesale electric 5 pence per kWhe and ROCs at £45
MWhe.
Beef, large
The costs were estimated for a unit comprising 500 finishers all indoors and a slurry/manure only
system with a capacity of 50 kW. Annual finance cost based on amortised capital investment. The
returns were calculated on the same basis as above.
Pigs, medium
The costs were estimated for a unit comprising 999 finishers and a slurry/manure only system with a
capacity of 30 kW. Annual finance cost based on amortised capital investment. Returns based on
SID 5 (Rev. 3/06)
Page 16 of 25
electricity and ROC prices as at 2009 i.e. wholesale electric 5 pence per kWhe and ROCs at £45
MWhe.
Dairy, large
The costs were estimated for a unit comprising 420 cows all indoors and a slurry/manure only system
with a capacity of 100 kW. Annual finance cost based on amortised capital investment. The returns
were calculated on the same basis as above.
CAD Poultry
These costs are based on 5 MW central plant plus importing organic wastes attached to a unit
comprising 477,066 layers. Annual finance cost based on amortised capital investment. The returns
were calculated on the same basis as above.
Beef, medium
The costs were estimated for a unit comprising 50 finishers all indoors and a slurry/manure only system
with a capacity of 5 kW. Annual finance cost based on amortised capital investment. The returns were
calculated on the same basis as above.
Dairy, medium
The costs were estimated for a unit comprising 99 cows all indoors and a slurry/manure only system
with a capacity of 30 kW. Annual finance cost based on amortised capital investment. The returns
were calculated on the same basis as above.
Soils improved drainage
Capital cost for installation of field drainage is estimated to be £2,450 - £2,950 per hectare. The SAC
report estimates that this will result in 10% increased yields assume a rotation of 50% wheat, 50% break
crop at 2009 prices.
Task 2 cost curve re-calculation
The abatement efficiencies used in the spreadsheet are somewhat arbitrary as the SAC MACC was
constructed using abatement as t CO2-eqv/ha or per animal place, whereas the more straightforward
approach is to express abatement as % of unabated emissions. Hence in some case we have had to
assume abatement efficiencies in our calculations such that they produce the abatement reported in the
SAC-MACC report. We then repeated the calculations using mean abatements and applicabilities we
report above and also the upper and lower estimates of abatement and applicability we consider
feasible.
Table 4. Estimates of abatement in 2022, in t CO 2-eqv., for the measures identified by the SACMACC output as having a potential abatement cost of no more than £26 t CO 2-eqv. SAC results
are for the Central Feasible Potential
Measure
SAC output
Beef Ionophores
Beef improved genetics
Soils mineral-N timing
Soils manure-N timing
Soils full manure-N allowance
Soils reduced tillage
Dairy improved productivity
Dairy Ionophores
Dairy improved fertility
Soils improved N use plants
Dairy maize silage
Soils avoid N excess
Soils used FYM/composts
Soils delay mineral-N /slurry
OFAD Pigs large
OFAD Beef large
OFAD Pigs medium
OFAD Dairy large
CAD Poultry
Soils improved drainage
OFAD beef medium
OFAD dairy medium
347.38
46.32
1150.39
1027.16
457.26
55.77
377.36
739.36
346.26
331.80
95.98
276.06
78.51
47.17
47.77
97.79
16.06
250.81
219.34
1741.02
50.77
44.12
Revised Central
Estimate
0.00
23.16
0.00
1027.16
118.77
5.58
377.36
0.00
346.26
110.60
95.98
27.61
0.00
47.17
47.77
97.79
16.06
250.81
219.34
870.51
50.77
44.12
Total
7844.46
3776.81
Revised min.
Revised max.
0.00
23.16
0.00
513.58
59.38
0.00
125.79
0.00
161.59
55.30
95.98
27.61
-235.53
18.87
31.53
64.54
10.60
165.53
144.76
348.20
33.51
29.12
347.38
46.32
0.00
2567.90
457.26
55.77
566.04
739.36
554.02
331.80
95.98
276.06
78.51
94.34
79.30
162.33
26.66
416.34
364.10
1741.02
84.28
73.24
1673.52
9158.01
Measures where the SAC and AEA estimates differ by more than a factor of 2 are in italics
SID 5 (Rev. 3/06)
Page 17 of 25
Table 4 shows our mean estimate of potential abatement in 2022 is c. 48% of that of the SAC output,
with a range equivalent to c. 21-117% of the SAC CFP. Our mean estimates are always equal or less
than the SAC estimatesand most (55%) of the discrepancy between the SAC and AEA total estimate is
down to differences on three measures: beef and dairy ionophores and mineral N timing. On these three
measures, AEA have adopted conservative assumptions regarding the “mean” abatement”, i.e. that it
would be 0. The maximum estimate largely arises as a result of using the greater end of the range of
reduction considered possible for improved manure N timing applied in livestock manures.
Table 5. First re-assessment of costs and cost-effectiveness, for 2022, using SAC input costs with
AEA/ASRG estimates of abatement potential. Mean, min. and max. refer to the AEA/ASRG estimates
of Central Feasible Potential abatement. Costs are £ per t CO 2-eqv. for each measure, Cumul. is the
cumulative cost
Measure
Beef Ionophores
Beef improved genetics
Soils mineral-N timing
Soils manure-N timing
Soils full manure-N allowance
Soils reduced tillage
Dairy improved productivity
Dairy Ionophores
Dairy improved fertility
Soils improved N use plants
Dairy maize silage
Soils avoid N excess
Soils used FYM/composts
Soils delay mineral-N /slurry
OFAD Pigs large
OFAD Beef large
OFAD Pigs medium
OFAD Dairy large
CAD Poultry
Soils improved drainage
OFAD beef medium
OFAD dairy medium
Total
SAC output
Cost
Cumul.
-1748
-774,111
-3603
-892,601
-103
-962,448
-68
-1030,580
-149
-1089,306
-1053
-1089,306
0
-1125,534
-49
-1125,534
0
-1150,751
-76
-1175,994
-263
-1189,797
-50
-1189,797
0
-1189,797
0
-1189,749
1
-1189,505
2.5
-1189,424
5
-1187,418
8
-1185,005
11
-1160,631
14
-1159,768
17
-1158,709
24
-774,111
Revised Mean
Cost
Cumul.
0
0
-1802
-41,723
0
-41,723
-68
-111,570
-149
-129,266
-105
-129,853
0
-129,853
0
-129,853
0
-129,853
-25
-132,655
-263
-157,898
-50
-159,278
0
-159,278
0
-159,278
1
-159,231
3
-158,986
5
-158,906
8
-156,899
11
-154,487
28
-130,112
17
-129,249
24
-128,190
Revised min.
Cost
Cumul.
0
0
-1802
-41,723
0
-41,723
-68
-76,646
-149
-85,494
0
-85,494
0
-85,494
0
-85,494
0
-85,494
-13
-86,195
-263
-111,438
-50
-112,818
0
-112,818
0
-112,818
1
-112,786
3
-112,625
5
-112,572
8
-111,248
11
-109,655
70
-85,281
17
-84,711
24
-84,013
Revised max.
Cost
Cumul.
-1748
-607,220
-3603
-774,111
0
-774,111
-170
-1210,654
-149
-1278,786
-1053
-1337,512
0
-1337,512
-49
-1373,740
0
-1373,740
-76
-1398,957
-263
-1424,200
-50
-1438,003
0
-1438,003
0
-1438,003
1
-1437,924
3
-1437,518
5
-1437,385
8
-1434,054
11
-1430,049
14
-1405,674
17
-1404,242
24
-1402,484
-774,111
-128,190
-84,013
-1402,484
Using the SAC cost estimates with the range of abatement/applicability potential proposed in Table 2,
the potential saving from implementing measures with an abatement cost of < £26 t CO 2-eqv. ranges
from c. £84 M (11% of SAC estimate) to £1402 M (*2 the SAC estimate) with a mean of £128 M (17% of
the SAC estimate). However, caution needs to be exercised with respect to these results. First, they
are based on SAC cost estimates which our review suggests may need adjusting. Second, much of the
potential savings in the maximum estimate arise from the use of ionophores which are currently not
allowed.
SID 5 (Rev. 3/06)
Page 18 of 25
Table 6. Estimates of abatement in 2022 for the measures identified by the SAC-MACC output
as having a potential abatement cost of no more than £26 t CO 2-eqv. SAC results are for the
Maximum Theoretical Potential (SAC Table E.2)
Measure
Beef Ionophores
Beef improved genetics
Soils mineral-N timing
Soils manure-N timing
Soils full manure-N allowance
Soils reduced tillage
Dairy improved productivity
Dairy Ionophores
Dairy improved fertility
Soils improved N use plants
Dairy maize silage
Soils avoid N excess
Soils used FYM/composts
Soils delay mineral-N /slurry
OFAD Pigs large
OFAD Beef large
OFAD Pigs medium
OFAD Dairy large
CAD Poultry
Soils improved drainage
OFAD beef medium
OFAD dairy medium
Total
SAC output
771.95
102.93
2556.41
2282.58
1016.13
123.93
838.57
1643.68
769.48
737.33
213.28
613.48
174.47
104.83
106.15
217.3
35.69
557.35
487.42
3868.93
112.82
98.05
Revised Mean
0.00
51.47
0.00
2282.58
263.93
12.39
838.57
0.00
769.48
245.78
213.28
61.35
0.00
104.83
106.15
217.30
35.69
557.35
487.42
1934.47
112.82
98.05
Revised min.
0.00
51.47
0.00
1141.29
131.96
0.00
279.52
0.00
359.09
122.89
213.28
61.35
-523.41
41.93
70.06
143.42
23.56
367.85
321.70
773.79
74.46
64.71
Revised max.
771.95
102.93
0.00
5706.45
1016.13
123.93
1257.86
1643.68
1231.17
737.33
213.28
613.48
174.47
209.66
176.21
360.72
59.25
925.20
809.12
3868.93
187.28
162.76
17432.76
8392.90
3718.91
20351.78
Table 6 shows our mean estimate of potential abatement in 2022 is c. 48% of that of the SAC output,
with a range equivalent to c. 21-117% of the SAC central feasible tendency. Our maximum estimate
largely arises as a result of using the greater end of the range of reduction considered possible for
making full allowance for the N applied in livestock manures.
Table 7. First re-assessment of costs and cost-effectiveness, for 2022, using SAC input costs with
AEA/ASRG estimates of abatement potential. Mean, min. and max. refer to the AEA/ASRG estimates
of Maximum Theoretical Potential abatement. Costs are £ per t CO2-eqv. for each measure, Cumul. is
the cumulative cost
Measure
Beef Ionophores
Beef improved genetics
Soils mineral-N timing
Soils manure-N timing
Soils full manure-N allowance
Soils reduced tillage
Dairy improved productivity
Dairy Ionophores
Dairy improved fertility
Soils improved N use plants
Dairy maize silage
Soils avoid N excess
Soils used FYM/composts
Soils delay mineral-N /slurry
OFAD Pigs large
OFAD Beef large
OFAD Pigs medium
OFAD Dairy large
CAD Poultry
Soils improved drainage
OFAD beef medium
OFAD dairy medium
Total
SAC output
Cost
Cumul.
-1748
-1349,369
-3603
-1720,225
-103
-1983,536
-68
-2138,751
-149
-2290,154
-1053
-2420,653
0
-2420,653
-49
-2501,193
0
-2501,193
-76
-2557,230
-263
-2613,323
-50
-2643,997
0
-2643,997
0
-2643,997
-2
-2644,256
-1
-2644,499
1
-2644,474
3
-2642,540
11
-2636,969
14
-2582,804
11
-2581,554
17
-2579,876
Revised Mean
Cost
Cumul.
0
0
-1802
-92,714
0
-92,714
-68
-247,930
-149
-287,255
-105
-288,560
0
-288,560
0
-288,560
0
-288,560
-25
-294,787
-263
-350,879
-50
-353,947
0
-353,947
0
-353,947
-2
-354,206
-1
-354,449
1
-354,424
3
-352,490
11
-346,918
28
-292,753
11
-291,503
17
-289,826
Revised min.
Cost
Cumul.
0
0
-1802
-92,714
0
-92,714
-68
-170,322
-149
-189,985
0
-189,985
0
-189,985
0
-189,985
0
-189,985
-13
-191,541
-263
-247,634
-50
-250,701
0
-250,701
0
-250,701
-2
-250,872
-1
-251,033
1
-251,016
3
-249,740
11
-246,063
70
-191,898
11
-191,073
17
-189,965
Revised max.
Cost
Cumul.
-1748
-1349,369
-3603
-1720,225
0
-1720,225
-170
-2690,322
-149
-2841,725
-1053
-2972,224
0
-2972,224
-49
-3052,764
0
-3052,764
-76
-3108,801
-263
-3164,894
-50
-3195,568
0
-3195,568
0
-3195,568
-2
-3195,998
-1
-3196,402
1
-3196,359
3
-3193,149
11
-3183,901
14
-3129,736
11
-3127,661
17
-3124,876
-2579,876
-289,826
-189,965
-3124,876
Using the SAC cost estimates with the range of abatement/applicability potential proposed in Table 2,
the MTP saving from implementing measures with an abatement cost of < £26 t CO 2-eqv. ranges from
c. £190 M (7% of SAC estimate) to £3125 M (+21% of the SAC estimate) with a mean of £290 M (11%
of the SAC estimate). However, as indicated above for the CFP, caution needs to be exercised with
respect to these results.
SID 5 (Rev. 3/06)
Page 19 of 25
Comments
Beef improved genetics, Dairy improved productivity, Dairy improved fertility, Soils improved N use
plants
Our assessment is that these may be less effective than considered by SAC. Hence per t CO 2-eqv.
abated the measure will be less cost-effective than estimated by SAC
Soils manure-N timing, Soils full manure-N allowance, Soils avoid N excess
For these measures the unit costs remain unchanged, but we consider the applicability of the measure
to be less than that assumed by SAC, hence total reductions in CO 2-eqv. and potential cost savings will
be less.
Apportioning abatement potential between England and UK
This was done by weighting the abatement estimated for each measure by the proportion of the relevant
sector in England according to table 6 below.
The proportions of the livestock sectors were estimated from the numbers of livestock reported for each
country in the UK Ammonia Emissions Inventory (Anon., 2008), while for fertilizer-related measures the
proportion of N fertilizer applied in England, also obtained from the Inventory, was used.
Table 8. Proportions of the relevant livestock sectors estimated for England.
Sector
Proportion found in England
Beef
0.520
Dairy
0.619
Pigs
0.816
Poultry
0.768
Fertilizer
0.729
Land
0.729
Table 9. Estimates of abatement in 2022 for the measures identified by the SAC-MACC output
as having a potential abatement cost of no more than £26 t CO 2-eqv. SAC results are for the
Central Feasible Potential, for England in comparison with the UK as a whole. Mean estimate of
abatement only.
Measure
Beef Ionophores
Beef improved genetics
Soils mineral-N timing
Soils manure-N timing
Soils full manure-N allowance
Soils reduced tillage
Dairy improved productivity
Dairy Ionophores
Dairy improved fertility
Soils improved N use plants
Dairy maize silage
Soils avoid N excess
Soils used FYM/composts
Soils delay mineral-N /slurry
OFAD Pigs large
OFAD Beef large
OFAD Pigs medium
OFAD Dairy large
CAD Poultry
Soils improved drainage
OFAD beef medium
OFAD dairy medium
Total
Revised UK
Mean
Abatement
0.00
23.16
0.00
1027.16
118.77
5.58
377.36
0.00
346.26
110.60
95.98
27.61
0.00
47.17
47.77
97.79
16.06
250.81
219.34
870.51
50.77
44.12
3776.81
0
-41723
-41723
-111570
-129266
-129853
-129853
-129853
-129853
-132655
-157898
-159278
-159278
-159278
-159231
-158986
-158906
-156899
-154487
-130112
-129249
-128190
Revised
England Mean
Abatement
0
12.04
0.00
699.08
80.83
4.06
233.59
0.00
214.34
80.59
59.41
20.11
0.00
26.86
38.97
50.83
13.10
155.25
168.42
634.27
26.39
27.31
-128190
2545.46
Cumul cost
Cumul cost
0
-21687
-21687
-69224
-81268
-81696
-81696
-81696
-81696
-83738
-99363
-100369
-100369
-100369
-100330
-100203
-100138
-98895
-97043
-79283
-78835
-78179
-78179
Hence, using this approach c. 67% of the potential for GHG abatement arises from agriculture within
England.
SID 5 (Rev. 3/06)
Page 20 of 25
Table 10. Estimates of abatement in 2022 for the measures identified by the SAC-MACC output
as having a potential abatement cost of no more than £26 t CO 2-eqv. SAC results are for the
Central Feasible Potential. England only
Measure
Beef Ionophores
Beef improved genetics
Soils mineral-N timing
Soils manure-N timing
Soils full manure-N allowance
Soils reduced tillage
Dairy improved productivity
Dairy Ionophores
Dairy improved fertility
Soils improved N use plants
Dairy maize silage
Soils avoid N excess
Soils used FYM/composts
Soils delay mineral-N /slurry
OFAD Pigs large
OFAD Beef large
OFAD Pigs medium
OFAD Dairy large
CAD Poultry
Soils improved drainage
OFAD beef medium
OFAD dairy medium
Total
Adjusted SAC
output
180.57
24.08
838.20
699.08
311.21
40.64
233.59
457.67
214.34
241.76
59.41
201.14
53.43
26.86
38.97
50.83
13.10
155.25
168.42
1268.55
26.39
27.31
Revised Mean
Revised min.
Revised max.
0
12.04
0.00
699.08
80.83
4.06
233.59
0.00
214.34
80.59
59.41
20.11
0.00
26.86
38.97
50.83
13.10
155.25
168.42
634.27
26.39
27.31
0.00
12.04
0.00
349.54
40.42
0.00
77.86
0.00
100.03
40.29
59.41
20.11
-160.30
10.74
25.72
33.55
8.65
102.47
111.16
253.71
17.42
18.03
180.57
24.08
0.00
1747.69
311.21
40.64
350.39
457.67
342.94
241.76
59.41
201.14
53.43
53.72
64.68
84.38
21.75
257.72
279.58
1268.55
43.81
45.34
5330.79
2545.46
1120.83
6130.44
These results suggest that c. 68% of the UK abatement potential may arise from agriculture in England.
Table 11. Estimates of abatement in 2022 for the measures identified by the SAC-MACC output
as having a potential abatement cost of no more than £26 t CO 2-eqv. SAC results are for the
Maximum Theoretical Potential. England only
Measure
Beef Ionophores
Beef improved genetics
Soils mineral-N timing
Soils manure-N timing
Soils full manure-N allowance
Soils reduced tillage
Dairy improved productivity
Dairy Ionophores
Dairy improved fertility
Soils improved N use plants
Dairy maize silage
Soils avoid N excess
Soils used FYM/composts
Soils delay mineral-N /slurry
OFAD Pigs large
OFAD Beef large
OFAD Pigs medium
OFAD Dairy large
CAD Poultry
Soils improved drainage
OFAD beef medium
OFAD dairy medium
Total
Adjusted SAC
output
401.25
53.50
1862.66
1553.50
691.57
90.30
519.09
1017.46
476.32
537.24
132.02
447.00
118.74
59.69
86.59
112.95
29.11
345.01
374.26
2819.00
58.64
60.69
Revised Mean
Revised min.
Revised max.
0
26.75
0.00
1553.50
179.63
9.03
519.09
0.00
476.32
179.08
132.02
44.70
0.00
59.69
86.59
112.95
29.11
345.01
374.26
1409.50
58.64
60.69
0.00
26.75
0.00
776.75
89.81
0.00
173.03
0.00
222.28
89.54
132.02
44.70
-356.23
23.88
57.15
74.55
19.21
227.70
247.01
563.80
38.70
40.06
401.25
53.50
0.00
3883.75
691.57
90.30
778.63
1017.46
762.11
537.24
132.02
447.00
118.74
119.38
143.74
187.50
48.33
572.71
621.28
2819.00
97.35
100.75
11,846.60
5656.56
2490.73
13,623.60
Since the same weighting was used for the MTP and for the CFP estimates, c. 68% of the MTP is also
predicted to arise from agriculture in England.
SID 5 (Rev. 3/06)
Page 21 of 25
Endnotes
1. SAC point out that 'efficiency' may be defined as the (a) abatement rate; (b) cost-effectiveness per
unit area; or (c) cost-eff per t CO2-eqv. There several reasons why the AP could be lower (or higher).
AEA have used efficiency to mean the % reduction of unabated emissions from the source to which the
measure has been applied that is achieved by implementation of the measure under consideration to
the source. The table below illustrate the conceptual difference in the approaches taken by SAC and
AEA. SAC have considered emissions per ha., whereas AEA have considered total emissions.
Reason for lower abatement
potential*
Cost/ha
Abatement
rate (CO2eqv./ha)
lower
CE
(£/t CO2eqv.)
lower
AP
(t CO2)
1. Measure reduces emissions per
same
lower
ha by less than predicted, with
same effort: e.g. improved drainage
2. Measure reduces emissions per
lower
lower
same
lower
ha by less than predicted, but with
proportionally less cost: e.g. amount
by which excess N can be reduced
is less than predicted
3. Measure AR and cost are as
same
same
same
lower
predicted, but the area it can be
applied to is overestimated, e.g.
ionophores
*This table is not exhaustive, e.g. it does not include scenarios where the costs vary but the
AR are constant
2. Definitions used in SAC MACC report
Term
Cost
Cost-effectiveness
(CE)
Abatement rate (AR)
Abatement potential
(AP)
Stand alone
Combined
SID 5 (Rev. 3/06)
Meaning
The cost per hectare (or per animal) of implementing a
measure, per hectare, per year.
The cost of reducing GHG emissions.
The rate at which a measure can reduce emissions,
per hectare (or per animal).
The total amount that GHG emissions can be reduced
by (usually per year).
The AR, AP or CE of a measure when applied in
isolation.
The AR, AP or CE of a measure when applied in
conjunction with other measures.
Page 22 of 25
Unit
£/ha/year
£/t CO2eqv.
t CO2eqv./ha
t CO2-eqv.
na
na
References
Anon. 2007. A review of research to identify best practice for reducing greenhouse gases from
agriculture and land management. Final report Defra project AC0206.
Anon. 2008. Inventory of Ammonia Emissions from UK Agriculture 2007. Annual report for Defra
Contract AC0112. Defra, October 2008.
Baker JM, Ochsner TE, Venterea RT, Griffis TJ. 2007. Tillage and soil carbon sequestration—what do
we really know? Agriculture Ecosystems and Environment 118, 1–5.
Ball BC, Rees RM, Sinclair AH. 2008. Mitigation of nitrous oxide and methane emissions from
agricultural soils – a summary of Scottish experience. Conference Proceeding.
Ball BC, Scott A, Parker JP. 1999. Field N2O, CO2 and CH4 fluxes in relation to tillage, compaction and
soil quality in Scotland. Soil and Tillage Research, 53, 29-39.
Bouwman AF, Boumans LJM, Batjes NH. 2002. Emissions of N 2O and NO from fertilized fields:
Summary of available measurement data. Global Biogeochemical Cycles 16, art-1058.
Dobbie KE, Smith KA. 2003. Impact of different forms of N fertilizer on N 2O emissions from intensive
grassland. Nutrient Cycling in Agroecosystems 67, 37-46.
FEC Services Ltd (2003) Anaerobic digestion, storage, oligolysis, lime, heat and aerobic treatment of
livestock manures. Final report to Scottish Executive:
http://www.scotland.gov.uk/Resource/Doc/1057/0002224.pdf
Gál A, Vyn TJ, Michéli E, Kladivko EJ, McFee WW. (2007). Soil carbon and nitrogen accumulation with
long-term no-till versus moldboard plowing overestimated with tilled-zone sampling depths. Soil &
Tillage Research 96, 42–51.
Godwin et al. 2008. The Current Status of Soil and Water Management in England Stoneleigh Park:
Royal Agricultural Society of England
Holmes MRJ, Ainsley AM. 1979. Nitrogen top-dressing requirements of winter oilseed rape. Journal of
the Science of Food and Agriculture 30, 119-128.
Johnson JMF, Franzluebbers AJ, Weyers SL, Reicosky DC. 2007. Agricultural opportunities to mitigate
greenhouse gas emissions. Environmental Pollution 150, 107-124.
Jones SK, Rees RM, Skiba UM, Ball BC. 2004. Greenhouse gas emissions from a managed
grassland. Global and Planetary Change 47, 201-211.
Jones SK, Rees RM, Skiba UM, Ball BC. 2007. Influence of organic and mineral N fertiliser on N2O
fluxes from a temperate grassland. Agriculture Ecosystems and Environment 121, 74-83.
McTaggart IP, Clayton H, Parker J, Swan L, Smith KA. 1997. Nitrous oxide emissions from grassland
and spring barley, following N fertiliser application with and without nitrification inhibitors. Biology and
Fertility of Soils 25, 261-268.
Mosier AR, Duxbury JM, Freney JR, Heinemeyer O, Minami K. 1998. Assessing and mitigating N2O
emissions from agricultural soils. Climatic Change 40, 7-38.
Mosier AR, Halvorson AD, Reule CA, Liu XJ. 2006. Net global warming potential and greenhouse gas
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1584-1598.
Six J, Ogle SM, Breidt FJ, Conant RT, Mosier AR, Paustian K. 2004. The potential to mitigate global
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SID 5 (Rev. 3/06)
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Smith KA, McTaggart IP, Tsuruta H. 1997. Emissions of N 2O and NO associated with nitrogen
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Stevens RJ, Laughlin RJ. 2001. Cattle slurry affects nitrous oxide and dinitrogen emissions from
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References to published material
9.
This section should be used to record links (hypertext links where possible) or references to other
published material generated by, or relating to this project.
SID 5 (Rev. 3/06)
Page 24 of 25
No reports have been published during the life of the project
SID 5 (Rev. 3/06)
Page 25 of 25