Transcript Potential measures and quantitative estimation of carbon

Carbon Sequestration in European
Agricultural Soils by 2010 Potential, Uncertainties,
Policy Impacts
Annette Freibauer
UCL
[[email protected]]
Mark D. A. Rounsevell
Pete Smith
Jan Verhagen
C fluxes in SOC in the 1st commitment period: BAU
t C ha-1 y-1
Cropland
Grassland
mean flux: +0.83 (0.40) t C ha-1 y-1 (source)
Total in EU-15: 77 (37) Tg C y-1
mean flux: -0.60 (0.65) t C ha-1 y-1 (sink?)
Total in EU-15: -30 (32) Tg C y-1
Total agricultural soils
Total in EU-15: 48 (37) Tg C y-1 (source)
Vleeshouwers & Verhagen, GCB 2002
Most promising measures
1 Promote organic input on arable land instead of grassland
(crop residues, cover crops, FYM, compost, sewage sludge)
2 Permanent revegetation of arable set-aside land (e.g. afforestation)
or extensivation of arable production by introduction of
perennial components
3 Biofuel production with short-rotation coppice plantations and
perennial grasses on arable set-aside land
4 Promote organic farming
5 Promote permanently shallow water table in farmed peatland
6 Zero tillage / conservation tillage
Potential per unit area
6
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t C-equ. ha-1 y-1
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Cropland
Grassland
Peatland
Uncertainty: spatial variability, soil and climate types; no human components
Factors limiting carbon sequestration
Sink saturation
Non-permanence
Availability of land and resources
Adoption of measures / contiguous?
Area and resources available
Cropland
more organic input
reduced tillage
extensification, perennials
bioenergy crops
organic farming
total area
million ha
73
Grassland (in rotation)
longer duration of leys
from leys to permanent grass
8.4
Peatland in agriculture
restoration of drained soil
3.6
limitations
suitable area
million ha
organic material
climate, soil
set-aside land
set-aside land
now 2% of cropland
~60?
63?
7.3
7.3
7
no need: set-aside
no need: set-aside
7.3
7.3
highly productive
<1-2
Ramsar, CBD!
Uncertainty: adoption rate, adoption time?
Feasible Potential in EU-15
8
Tg C-equ. y-1 in EU-15
7
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Cropland
Grassland
Peatland
Uncertainty: spatial variability, adoption, permanence of adoption
Environmental effects
Tillage Amendments Extensif. Peatland
?
Herbizides, pestizides
Non-CO2 gases
NH3, NOx
Biodiversity
?
?
?
Water quality
Soil quality
Sustainable land
management
Productivity?
Farm income
Organic amendments
positive long-term, easy, cheap
Bioenergy crops
Organic farming
region-specific, emerging markets
region-specific, emerging markets
Reduced tillage
region-specific, risks, long-term benefits
Extensification
Peatland restoration
region-specific, compensation payments?
region-specific, compensation payments?
• Judgements about farm incomes are always qualified by
location – we cannot generalise!
• different soil types, climates and farm structures
• A modelling approach to address this problem and to provide
better quantification?
Policy impacts
Putting C sequestration options into a
real-world context influenced by policy
Policy effects
(post 1990)
Land use
change
Other effects
C sequestration
potential
Policy changes post 1990
• Radical changes in the structure of the CAP driven
by the 1992 MacSharry reforms and Agenda 2000
• From production-based price support to area
payments and set-aside
• A wealth of rural development and agrienvironmental policies
Policy effects on land use
• Market support (intervention, import duties) that
maintain producer prices
• Production controls
- quota: number of dairy cows declining
- set aside: C sequestration, biofuels
• Direct aid payments (arable area, agrienvironment)
- change in permanent crop production systems
- maintenance of meadows in LFA
- forestation of agricultural land
Conclusions (1)
• Policy changes post 1990 have probably had an
overall +ve effect on C sequestration
• But, uncertainties surround the effects of some
policies (LFAs, NVZs, organic) and their impacts
on farm incomes
• Policy could contribute further to soil C
sequestration in Europe
• Further research should target policy as well as
management options, be geographically explicit and
tackle impacts on farm incomes
Conclusions (2): Caveats
C balance in grasslands?
What measures are best adjusted to regional
management preferences?
Regional land use / land management history
Regional best practice
Permanent, contiguous, long-term adoption of measures?
Monitoring!
Costs?
Regional modelling for potential, adoption, income necessary
Regional refinement of policy measures necessary
Availability of land and resources / potential
Measure
Limiting factor
Soil carbon sequestration (Mt CO2 y-1)
Theoretical
Technical
Economic?
all agric.
Given
feasible
land used
limitation by 2012
Cropland
Zero-tillage
Suitable land = 63 Mha
103
Reduced-tillage
Suitable land = 63 Mha
< 103
Set-aside
<10% of arable; < 7.3 Mha
103
Perennial grasses and
permanent crops
No incentives to grow more
165
Deep-rooting crops Research and breeding
needed for annual crops
165
-1
Animal manure
Manure avail. = 385 Mt dm y 100
Crop residues
Surplus straw = 5.3 Mt dm y-1 185
Sewage sludge
Sewage sludge = 71 Mt dm y-1 69
Composting
Compost available at present
= 160 t dm y-1 (8 M ha)
100
Improved rotations
0
Fertilisation
0
Irrigation
0
Bioenergy crops only current set-aside = 7.3 Mha 165
Extensification current set-aside to extensify
30% of arable agr. = 20 Mha
144
Organic farming Could increase to 10% = 7.3 Mha 0-144
89.28
<89.28
Max = 8.93
8.93
<8.93
0
0?
0?
0?
86.83
90.46
6.30
0?
?
?
?
11
>0
0
0
16.52
11?
0?
0
0
3.3
41.63
14.40
?
14.4
Availability of land and resources / potential
Measure
Grassland
?
Limiting factor
Knowledge!
Soil carbon sequestration (Mt CO2 y-1)
Theoretical
Technical
Economic?
all agric.
Given
feasible
land used
limitation by 2012
?
?
?
Revegetation
Abandoned
arable land
Land conversion
Arable to
woodland
Arable to
grassland
Grassland to
arable
Permanent crops
to arable
Woodland to
arable
current set-aside = 7.3 Mha
165
current set-aside = 7.3 Mha
165
current set-aside = 7.3Mha
Land-use change since 1990
calculated as 2.7 Mha
Land-use change since 1990
calculated as 0.4 Mha
Negligible land-use change
since 1990
140
-266
16.52
Max. 16.52
16.52
Max. 16.52
14
0
-10 (since 1990) Future = 0
-42.5
-1.46 (since 1990)
0
=>-266
0
0
Availability of land and resources / potential
Measure
Limiting factor
Farmed organic soils
Protection and
Assuming all cultivated
restoration
organic soils are restored
Soil carbon sequestration (Mt CO2 y-1)
Theoretical
Technical
Economic?
all agric.
Given
feasible
land used
limitation by 2012
>36
>36
>36
Avoid row crops
and tubers
No incentive
0 GHG: 2
0?
0?
Avoid deep
ploughing
3 GHG: 3
0?
0?
15
15
More shallow
water table
Convert arable
to grassland
Convert arable
to woodland
No incentive
Possibly attractive on grassland when new melioration
is needed = 50 % of grass- 36 GHG: 36
land area = 1.5 Mha
No incentive
3 GHG: 3
Subsidies compensate income
losses: adoption rate max.
2 GHG: 3
50 % of arable area = 0.3 Mha
0?
1
0?
1
Non-CAP effects
• Technological change (plant & animal breeding)
• World markets & international trade agreements
• Changing consumer preferences – less meat, shifts
from olive to sunflower oil, etc.
• Opportunity costs of labour, i.e. competition with
other sectors
• Land degradation (e.g. erosion)
• Irrigation water availability and quality
• Education and information dissemination