Greenhouse gas emissions from food and biofuel production: Contribution of soil N2O emissionsLouise Barton1, Wahidul Biswas2, Klaus Butterbach-Bahl3, Ralf

Kiese3, Daniel Carter4 and Daniel Murphy1

1University of Western Australia

2Curtin University of Technology

3Department of Agriculture & Food Western Australia

4Institute for Meteorology & Climate Research, Germany.

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CARBON FOOTPRINTING:Gaining the “Competitive Advantage”

GREENHOUSE GASES & AGRICULTURAL PRODUCTION

CO2-EQU

(100 years)

SOURCES

CO2 X 1 Transportation, manufacturing inputs, electricity

CH4 X 25 Transportation,

manufacturing inputs

N2O X 298 N fertiliser production, land emissions

Source: Forster et al. 2007. Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Cambridge University Press.

NO2- NO N2O N2

N2O NO3-

NH3 NH2OH NO2

- NO N2O N2

Nitrification

Nitrifier Denitrification

Denitrification

N2O FROM SOILS

• Default emission factorfert = 1.0%

• Emission factorfert:

(N2O-Nfertilised soil – N2O-N non-fertilised soil ) * 100

Nitrogen applied

• Required to use default value in the absence

of published, country specific values

CALCULATING SOIL N2O EMISSIONS:National Inventories & LCA

• > 200 studies

• Temperate climates

• Ammonium nitrate, CAN, organic N

• Sandy loam to clay soils

• Few studies in semi-arid regionsSources: Bouwman et al. 2002. Global Biogeochemical Cycles 16:1058; Galbally et al. 2005. Environmental Sciences 2: 133–142; Stehfest & Bouwman 2006. Nutr Cycle Agroecosystems 74: 207–28; Galbally 2009. Journal of Environmental Quality 37: 599–607.

DEFAULT N2O EMISSION FACTORFERT

Calculate GHG emissions from the production of wheat and biodiesel in south-western Australia by:

• Measuring in situ soil N2O emissions continuously

from wheat/canola production for 3 years; and

• Incorporating these ‘local’ soil N2O emission data

into a life cycle assessment (LCA) of GHG

emissions.

OUR AIMS

REFINING N2O EMISSIONS

CUNDERDIN, WA

• Semi-arid environment

• 156 km east of Perth, WA

• Rainfall: 368 mm yr-1

• Air Temperature:

– Mean min:11.4 °C – Mean max temp: 25.1 °C

• Crops grown in winter, soil ‘fallow’ during summer

50 cm x 50 cm x variable height (15–95cm)

Jun-05 Dec-05 Jun-06 Dec-06 Jun-07 Dec-07 Jun-08

N2O

flu

x (g

N2O

-N h

a-1 d

ay-1

)

-2

0

2

4

6

8

10

12 No N Plus N Fertiliser

DAILY N2O EMISSIONS: 3 Years

Wheat Wheat CanolaSource: Barton et al. 2010. GCBB 2: 1‒15 ; Barton et. al. 2008. GCB 14: 177-192.

N applied Total loss Emission factor

(kg N ha-1 yr-1) (%)

Canola 2007/08 75 0.13 0.06

Wheat 2006/07 75 0.13 0.02

Wheat 2005/06 100 0.11 0.02

AUSTRainfed crops 0.11–1.2 0.3

GLOBALLY Crops 0.11–17 1.00

In Australia’s <550 mm rainfall regions: N2O EFFert will change from to 0.3% to 0.08%

ANNUAL N2O EMISSIONS

LIFE CYCLE ASSESSMENT: Wheat Production

LCA METHODOLOGY: Wheat Production

• Goal

Estimate total GHG emitted during the production and transport of rain-fed wheat grown in in south-western Australia

• Function Unit

Delivery of 1 tonne of wheat to port

• Life Cycle Inventory (LCI)

Calculated using Simapro 7, with libraries developed by RMIT, or using local information

Source: Biswas et. al. 2008. Water and Environment Journal 22: 206-216

WHEAT PRODUCTION GHG EMISSIONS: International N2O default value (1.0%)

Production of urea and superphosphate

24%

Production of herbicide

6%

N2O emissions from paddock

36%

Farm machinery production

6%

CO2 emission from urea hydrolysis (from paddock)

19%

Transportation of inputs and wheat

9%

487 kg of CO2 equ- per tonne

Source: Biswas et. al. 2008. Water and Environment Journal 22: 206-216

WHEAT PRODUCTION GHG EMISSIONS: ‘Local’ N2O value

304 kg of CO2 equ- per tonne

12%

operation

27%

Prduction of

Production of urea and superphosphate

35%

Production of herbicide

9%

N2O emissions from paddock

9%

Farm machinery production

8%

CO2 emission from urea hydrolysis (from paddock)

27%

Transportation of inputs and wheat

12%

9%

8%

paddock

2

35%

Source: Biswas et. al. 2008. Water and Environment Journal 22: 206-216

LIFE CYCLE ASSESSMENT: Biodiesel Production &

Combustion

• Goal

Estimate GHG emitted from production and combustion of biodiesel (canola oil) produced from grain grown in south-western Australia

• Function Unit

Production and combustion of one GJ of canola based biodiesel

• Life Cycle Inventory (LCI)

Calculated using Simapro 7, with libraries developed by RMIT, or using local information

LCA METHODOLOGY: Biodiesel Production & Combustion

GHG EMISSIONS FROM BIODIESEL PRODUCTION & COMBUSTION : International N2O default value (1.0%)

63 kg CO2 equ-/GJ

Source: Biswas et. al. 2011. Environmental Science & Technology (accepted).

Paddock N2O emissions

49%

Urea hydrolysis15%

Farm machinery operation

3%

Canola seed to oil2%

Fertiliser production

17%

Herbicide & Pesticide production

10%

Transportation3%

Canola oil to biodiesel 1%

GHG EMISSIONS FROM BIODIESEL PRODUCTION & COMBUSTION : ‘Local’ N2O value

37 kg CO2 equ-/GJ

35%

Paddock N2O emissions

13%

Urea hydrolysis25%

Farm machinery operation

6%

Canola seedto oil 4%

Canola oil to biodiesel 2%

Fertiliser production

29%

Pesticide production

1%

Herbicide production

16%

Transportation4%

Source: Biswas et. al. 2011. Environmental Science & Technology (accepted).

CONCLUSIONS

• IPCC emission factor (Effert) overestimates soil N2O emissions from Australian rain-fed, cropping systems

• ‘Life Cycle Assessment’ of GHG from food and biofuel production is sensitive to soil N2O emissions, and analysts need to consider the implications of utilising international default values.

• Obtaining soil N2O estimates is costly and time-consuming, and requires a national coordination

ACKNOWLEGMENTS• Research funded by the Department of Climate

Change, Grains & Research Development Corporation (GRDC), Department of Agriculture & Food Western Australia

• Presenting author currently funded by GRDC and the Australian Government’s Climate Change Research Program

GHG Emissions: Biodiesel vs. Diesel

Mineral Diesel Sources: Beer et al. 2007. Report Number KS54C/1/F2.29, CSIRO; Grant et al. 2008. Report KN29A/WA/F2.5, DAFWA.

kg C

O2

-e/G

J

37 37

16

54

70

11

67

78

Production Combustion Total

BD100 BD20 Diesel