Identifying and managing emissions from farms and food chains

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Identifying and managing emissions from farms and
food chains
Presented at Carbon Footprint Supply Chain
Summit, 24-25 May 2007, London

• Gareth Edwards-Jones
• Georgia Koerber Liz York
• Llorenç Milà i Canals
• University of Wales, Bangor
• University of Surrey

Contact g.ejones_at_bangor.ac.uk
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Key messages

• Lack of knowledge
• Complexity
• We can assume too much
• Based on on-going research Comparative
  assessment of the advantages and disadvantages of
  growing fruit and vegetables in the UK and
  overseas funded by the UK Research Councils
  Rural Economy and Land Use programme (RELU).

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Outline

• Definitions
• Different ways of estimating carbon footprint
• Commercial relevance of these different
  measurement methods
• Overview of agricultural emissions and what it
  means
• What does this mean for business and the planet?

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Carbon is not the only cause of climate change

• Nitrous oxide (N2O) 1kg 296 kg CO2-eq/kg
• Methane (CH4) 1 kg 23 kg CO2-eq/kg
• Others include CFCs, halons, methyl bromide,
  sulphur hexafluoride, halogenated HC,
  mono/di/trichloromethane)
• So to get the whole picture we really need to
  talk about
• GLOBAL WARMING POTENTIAL (GWP)

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Method 1 food miles
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Emissions from food miles
Transport type kg CO2 (direct)/tkm kg CO2-eq (GWP)/tkm
Passenger car 0.191 kg /passenger km 0.203 kg /passenger km
Van lt3.5t 1.076 1.118
Truck, 16t 0.304 0.316
Truck, 32t 0.153 0.157
Plane, freight 1.093 1.142
Train, freight 0.037 0.038
Transoceanic freight 0.010 0.011
Transoceanic tanker 0.005 0.005
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Assessment
Measure Comprehension by public Measurement and calculation Planet saving ability
Food miles High Easy Poor
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Method 2 Life Cycle Assessment (LCA)
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The food system
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The LCA for inputs to potatoes in UK

• Global Warming Potential (GWP 100 years) kg
  CO2-Equiv./tonne potatoes at the farm gate
• Fertiliser 42
• Pesticide 2.5
• Machinery 5.1
• Mechanisation 66.4

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Normalised impact assessment for watercress
sourced from the UK (organic and conventional),
the USA (organic and conventional) and Portugal
(conventional) (Sim et al. 2006)
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Lettuce data on measurement v standard

• GWP CO2-equiv (100yrs) per kg of lettuce at the
  farm gate for 2 UK farms supplying lettuce
  between January and April.
• Farm 1 3.72 kg CO2-equiv
• Farm 2 1.18 kg CO2-equiv

Source Mila i Canals et al .(2007a)
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Primary energy use per kg of apples from European
and Southern Hemisphere suppliers for the
different seasons (Mila i Canals et al .2007b)
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Assessment
Measure Comprehension by public Measurement and calculation Planet saving ability
Food miles High Easy Poor
Standard LCA Medium - high Medium Medium


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Soil the missing elephant
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or put more simply..
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Plant material
Fertiliser (organic and inorganic)
Humus or organic matter or soil organic carbon
MICROBIAL COMMUNITY
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Comparative losses in Carbon
1 Gt 1015g

• The UKs current industrial CO2 emission is 0.04
  G tonnes C per year (and falling) (Bellamy et al
  2005).
• One study suggests that since 1978 UK soil has
  lost 0.013 G tonnes C per year based on change in
  soil organic carbon (Bellamy et al. 2005).
• Therefore, UK soils are losing carbon from soil
  at one third the rate of industrial emissions.
• The fuel used to import food and drink to the UK
  accounts for 0.001 G tonnes C per year (Pearce
  2006).
• If these figures are correct UK soils are losing
  carbon at 13 times the rate of emissions from
  food imports.

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Nitrous oxide

• Between 66 and 70 of N2O emissions are derived
  from soil (IPCC 2000 Bouwman 1990).
• English emissions in 2002
• synthetic fertiliser application (27)
• leaching of fertiliser nitrogen to ground and
  surface water (26)
• wastes from grazing animals (13)
• ploughing in crop residues (13)
• manure used as fertiliser (8)
• atmospheric deposition of ammonia (NH3) and
  oxides of nitrogen (NOx) (6)
• cultivation of legumes (2)
• cultivation of histosols (i.e. high organic
  content soils) (0.7)
• biological fixation in improved grass (0.5)
• (Defra 2004)

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Soil Emissions of Nitrous Oxide and Methane

• Applying a typical emission factor of 2.2, leads
  to an emission of 6.6 to 13.2 kg N2O-N ha-1
  (Tzilivakis et al., 2005).
• Equivalent to CO2 emissions in the range of 3 to
  6 CO2-Equiv./tonne/ha
• The soil organic content to typical agricultural
  land is
• 440 CO2-Equiv./tonne/ha
• Relatively small emissions of N2O can exert a
  strong influence on the total GWP of an
  ecosystem.

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Methane

• UK agriculture emits 873,000 t methane per year.
• Land fill emits 928,000 t a lot of this from
  food waste
• Cattle responsible for 70 of the agricultural
  emissions.
• 87 of total emissions is due to enteric
  fermentation.
• Agricultural soils with plenty of oxygen are
  actually methane sinks.
• (Defra 2004)

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The public and The Green Room

• But to say that soil itself contributes to
  greenhouse gas should make people either alarmed
  or sceptical about this report's implications..
• Jeremy Mason
•  
• This article is short-sighted, inaccurate, and
  misleading. To insinuate that the green house
  gasses from the soil are responsible for
  environmental degradation is ridiculous.
• D., USA
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• The bit about the gases produced by different
  kinds of soil seems to me unnecessary for the
  issue at hand, unless the author is claiming that
  significant pollution results from our choice of
  soil. THAT would be news.
• Dustin, Philadelphia

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Variation with emissions

• Gaseous emissions from soils differ with
• Temperature
• Soil type
• Soil moisture
• Crop?
• Crop management?

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Effect of temperature on CO2 emissions
Source York unpublished
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Regional distribution of average emissions of
CO2-equivalents from soils, normalised by the
area of agricultural land in the NUTS 2 regions
(Freibauer 2003).
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Average emissions of CO2-equivalents per hectare
from agricultural ecosystems in Europe (Freibauer
2003).
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Soil Temperature 0C

Soil CO2 Efflux /- 2 SEM (µmol.m-2.s-1)
Soil CO2 Efflux /- 2 SEM (ton.ha-1.yr-1)
Time of Day
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Assessment
Measure Comprehension by public Measurement and calculation Planet saving ability
Food miles High Easy Poor
Standard LCA Medium - high Medium Medium
LCA with soil emissions Low Hard Better

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Summary so far

• So the missing element from many carbon
  footprints so far relates to the absence of
  measured emissions data which clearly vary a
  lot over time and space.
• But its even worse than that..

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Carbon Budget Studies
Description of Study NEP (t C ha-1 yr-1)
Winter wheat (Triticum aestivum L.), Thuringia, Germany (Anthoni et al., 2004). 1.85-2.45 (Eddy Covariance) 2.52 0.34 (Calculated)
Mixed coniferous- broadleaved foresta, meadow steppeb and typical steppec, North East China Transect (Zhou et al., 2002). 5.03a, 2.27b and 1.75c
No till, bare field with only wheat straw (Triticum aestivum L.) additions, Ohio USA (Duiker and Lal, 2000) Annual straw addition rate 0 2 4 8 16 3.84 5.64 4.51 5.34 6.63
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Carbon Budget Studies
Description of Study NEP (T C ha-1 yr-1)
Corn/Soybean Conventionald (full width tillage) versus Alternativee (reduced tillage, spring oats before barley) (Baker and Griffis, 2005) 3.76d, 3.50e
Restored prairie Maize, no-tillage, unfertilised Maize chisel-plowed, unfertilised Maize no-tillage, fertilised Maize chisel-plowed, fertilised (Brye et al., 2002) -1.7 0.6 -0.3 1.1 2.5
Onion (Allium cepa L.) Fertilised Mikasa, Japan. Unfertilised (Hu et al. 2004) Fertilised, bare Unfertilised, bare 1999 2000 0.02 and 0.27 -0.28 and -0.70 -1.9 and -2.1 -2.1 and -2.2
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Assessment
Measure Comprehension by public Measurement and calculation Planet saving ability
Food miles High Easy Poor
Standard LCA Medium - high Medium Medium
LCA with soil emissions Low Hard Better
LCA with full carbon budget Low V. hard The best

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Key messages for those devising carbon footprints
for agriculture

• Need a Systems approach.
• There is considerable diversity in food
  production systems and the environments where
  they occur.
• Collection of system / site specific data is
  important.
• Standard databases will improve with time but
  have deficiencies at the moment.

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GHG Account for UK agriculture, land use and
forestry (2004)
Category CO2 equivalent (millions of tonnes)
Enteric fermentation 16.9 34.7
Manure management 3.4 7.0
Agricultural soils 26.4 54.2
Agriculture total 46.8 96
Land use change Forestry (net) 1.9 4
Netcen (2004)
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Means of achieving carbon neutral foodin the
food chain

• Renewable energy for manufacturing inputs
• Energy efficient food transport
• Energy efficient food storage
• Energy efficient kitchens
• Reduce waste
• Reduce land used in food production and have more
  wild land to act as a carbon sink.
• Close nutrient cycling loop by putting food waste
  (and STW) back to land
• Fewer people?

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Means of achieving carbon neutral foodon the
farm

• Reduce methane production from ruminants
• Reduce emissions of N2O
• Reduce emissions of CO2

• Feeding strategies
• GM
• Fewer animals

• Reduce fertiliser use
• Better timing of fertiliser
• GM N-fixing crops

• Reduce cultivations
• Reduce cultivated area

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Will carbon accounting save the planet?

• NO
• But its more likely to help if.
• The public understand the issues and care enough
  to use the market to bring about change.
• Business and Government use the correct science.
• Scientists communicate clearly and understand the
  needs of business.