ACV, lechuga,fresas...

Journal of Cleaner Production 28 (2012) 81e87
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Journal of Cleaner Production
journal homepage: www.elsevier.com/locate/jclepro
Evaluating the global warming potential of the fresh produce supply chain for
strawberries, romaine/cos lettuces (Lactuca sativa), and button mushrooms
(Agaricus bisporus) in Western Australia using life cycle assessment (LCA)
Maria G.A. Gunady a , Wahidul Biswas b, *, Vicky A. Solah a , Anthony P. James a
a School of Public Health, Curtin Health Innovation Research Institute, Curtin University, GPO Box U1987, Perth 6845, Western Australia, Australia
b Centre for Excellence in Cleaner Production, Curtin University, GPO Box U1987, Perth 6845, Western Australia, Australia
article
info
abstract
Article history:
Received 23 May 2011
Received in revised form
19 December 2011
Accepted 27 December 2011
Available online 2 January 2012
Keywords:
Life cycle assessment
Carbon footprint
Strawberries
Mushrooms
Lettuces
A life cycle greenhouse gas (GHG) assessment of 1 kJ of strawberries, button mushrooms (Agaricus bisporus),
and romaine/cos lettuces (Lactuca sativa) transported to retail outlets in Western Australia (WA)
was examined and compared. The study included pre-farm, on-farm, and post-farm emissions. The prefarm
stage included GHG emissions from agricultural machinery and chemical production, and transport
of raw materials (spawn, peat, and compost) in mushrooms. The on-farm stage included GHG emissions
from agricultural machinery operation, chemical use, water for irrigation, waste generated, as well as
electricity and energy consumption. The post-farm stage included transport of produce to Distribution
Center (DC), storage in DC, and transport to retail outlets. The ‘hotspots’ or the stages that emit the
highest GHG were determined for strawberries, button mushrooms and romaine/cos lettuces. The results
have shown that the life cycle GHG emissions of strawberries and lettuces were higher than mushrooms
due to intensive agricultural machinery operations during the on-farm stage. Mushrooms, however have
significantly higher GHG emissions during pre-farm stage due to transport of peat, spawn, and compost.
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
Climate change has emerged as the most pressing global environmental
problem as the concentration of greenhouse gas (GHG)
in the atmosphere continues to increase. According to Intergovernmental
Panel for Climate Change (IPCC) (IPCC, 2001), the accumulated
emissions of GHG have already caused a global mean
surface air-temperature increase of between 0.3 and 0.6 C during
the past century, with the climate expected to change with an
average rate of warming greater than the last hundred centuries.
According to CSIRO (CSIRO, 2007), Australia’s per capita emissions
of greenhouse gas (GHG) were 4.5 times the global average and it
contributes 1.43 percent of the world’s GHG emissions. Australia
has participated in numerous bilateral and multilateral climate
change partnerships and the country also ratified the Kyoto
Protocol in 2007 (Department of Climate Change, 2009).
Whilst the agricultural sector accounts for 3% of GDP in Australia,
in 2008 it accounted for 16% of Australia’s total net GHG
emissions in the National Greenhouse Gas Inventory (Biswas et al.,
* Corresponding author.
E-mail address: w.biswas@curtin.edu.au (W. Biswas).
2010). These GHG emissions from agricultural sector will continue
to increase as Australia’s agricultural export production is predicted
to double over the next decade (CRC Plant Biosecurity). Additionally,
as the Australian population is predicted to reach 42.5 million
by 2056 (Australian Bureau of Statistics, 2008), the national food
and fuels consumption is expected to increase. Climate change is
currently the most pressing issue associated with the agricultural
practices in Australia, especially as public concern and media
scrutiny are mounting about the way food is produced and
distributed through markets. Gunasekara et al. (2008) also
concluded that Australia is predicted to be severely affected from
the future changes in climate in terms of reductions in agricultural
production and exports. In addition, climate change also threatens
Australia’s agricultural sustainability through water scarcity,
drought, and soil degradation; thereby affecting Australia’s
economy as well as food prices (Horne et al., 2009).
Whilst the horticulture sector produces a small amount of GHG
emissions (i.e. 1% of total agricultural emissions (Horticulture
Australia Limited, 2005)), the emissions intensity per hectare of
land is equivalent to, or even greater than, other agricultural
industries. The GHG emissions from the horticulture sector is expected
to grow for a number of reasons: Firstly the horticulture
sector, being the second largest sector of Australian agriculture
0959-6526/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jclepro.2011.12.031

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M.G.A. Gunady et al. / Journal of Cleaner Production 28 (2012) 81e87
contributed an average $6.9 billion per annum (or 1% of GDP) in
2003/04. This sector also employs over one hundred thousand
people annually (or 1.1% of national employment) (Horticulture
Australia Limited, 2005). Secondly, the levels of horticulture
production would need to increase dramatically in order to supply
the projected increased demand of fruits and vegetables as the per
capita intake is well below those recommended by government
health departments (Pollard et al., 2009). For example, only 8% of
Australian adults were consuming the minimum amount of fruit
and vegetables recommended by WHO (i.e. 400 g per day)
(Baghurst et al., 1999). In order to cope with the future fruit and
vegetable demand and climate change policy, it is, therefore,
important for growers to understand where emissions come from
and how they can be abated, as there is potential opportunities for
these growers to increase efficiencies and thus reduce input costs
on farm (Department of Climate Change, 2007).
The horticultural industry however consumes a significant
amount of energy due to agricultural machinery operation, irrigation,
chemical use, transport, and refrigerated storage. This energy
consumption contributes to the emission of greenhouse gases
(GHGs) mainly carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous
oxide (N 2 O) (Horne et al., 2009). Nitrous oxide (N 2 O), although
present as a trace gas in the atmosphere, is a long lived greenhouse
gas with an atmospheric lifetime of 120 years and is 310 times more
powerful GHG than CO 2 predominantly emitted due to fertilizer
application; while methane possesses 21 times the global warming
potential of CO 2 over a 100 year period (IPCC, 1996). Hence, there is
a need to assess the global warming potential from horticulture
production to identify GHG mitigation measures. A ‘life cycle
assessment’ (LCA) can be undertaken to account for all GHG
emitted for horticulture production so that mitigation strategies
focus on the primary sources of the GHG emissions. A LCA compiles
the inputs and outputs from a production system, and in turn
evaluates their potential environmental impacts (e.g., GHG emissions)
(Greadel et al., 2003a, b).
Thus, the current research focuses on the determination of
global warming impact or carbon footprint (i.e. life cycle GHG
emissions) of horticultural products and identifies ‘hotspots’
requiring mitigation strategies to reduce GHG emissions from the
production and delivery of three important produce in Australia.
Over the past decade, numerous studies have concentrated on
reducing GHG emissions and other environmental impacts from the
production of fresh produce. Mila I Canals et al. (2006) conducted
a life cycle assessment of (LCA) of apple production in two different
New Zealand regions. Carlsson-Kanyama (1998) studied the life cycle
greenhouse emissions from the production of different produce
(i.e. carrots, tomatoes, potatoes, pork, rice, and dry peas) in Sweden.
All these studies had quantified the life cycle GHG emissions of
different foods and also these studies are regarded as streamlined life
cycle assessment as they do not take into account the two extremes
of the produce life cycle (Todd and Curran, 1999). Life Cycle Assessment
(LCA) method is increasingly being used by horticultural
enterprises as it can provide insights into the environmental impacts
associated with the provision of agricultural products.
Several LCA studies have also investigated the environmental
impacts of different transport methods in order to determine the
most environmentally benign food distribution system. Roy et al.
(2009) compared the GHG emissions in distributing tomatoes by
road and sea, while Hospido et al. (2009) compared the global
warming impacts of supplying local and imported lettuces to
British retail outlets. However, none of these studies have been
specifically designed and conducted in Western Australia, where
climate and soil conditions are different and where food sources are
often so far away and generally distant from the metro market
(Biswas et al., 2010, 2008).
The World Trade Organization (WTO) is increasingly focusing on
trade rules relating to environmental protection policies (Mech and
Young, 2001). The growers are constantly facing the challenge to
provide ‘clean and green’ produce, as demands are increasing in the
Australian market. This is because the retailers are now requiring
their suppliers to verify that the food they purchase is safe
(i.e. ‘clean’) and, increasingly, produced in an environmentally
friendly manner (i.e. ‘green’) (Newton, 2007).
Therefore, in order to grow produce with lower environmental
impacts, the current research used LCA in order to assess the emissions
of GHG from the production and delivery of three important
produce in Western Australia, namely strawberries, button Agaricus
bisporus mushrooms, and romaine/cos lettuces. These industries
have grown steadily over the past years, supplying domestic markets
with good quality produce. The majority (86%) of the Australian
households nowadays buy mushrooms for which Australian annual
per capita mushroom consumption jumped from 0.6 kg in 1974 to
3.0 kg in 2005/06 and around 38% of primary grocery shoppers
always have mushrooms on their shopping list (Horticulture
Australia Limited, 2007). In the case of lettuce 70 percent of
Australian purchased lettuce as one of the main primary staple foods
(Rogers, 2006). These two vegetables together accounts for about
13% of the total vegetables sold in Australia (Department of
Agriculture, Fisheries and Forestry, 2005). On the other hand, the
strawberry industry anticipates a 10% growth in volume during the
next five years due to new consumer preferred varieties and an
increase in plant yield (Horticulture Australia Limited, 2009). The
strawberries and lettuce are grown in Western Australia all year
long.
In addition, these three types of produce were chosen for this
LCA analysis, because they are perishable, and so require more
energy for storage and packaging than that needed for other
horticultural products (e.g. potatoes, oranges etc.). For example,
according to Australian supermarket (e.g. Coles) quality management
standard, the ideal storage temperature for all 3 products is
0e5 C and all products can show deterioration in color and texture
over a 5-day period that result in being categorized as having
a major defect. Secondly, these storage and packaging processes
have significant greenhouse gas implications in product supply
chain. Thirdly, these products require inputs to be imported from
different states and even from overseas resulting in
environmental emissions from transportation. These three
produce need to be transported long distance from Perth, such as
Broome. Fourthly, the carbon footprints of these three types of
produce were determined as these produce are widely eaten
Western Australian produce (National Health and Medical
Research Council, 2011). Fifthly, these products are sold in the
same grocery store and thus complete the same stages of upstream
activities from ‘grower to grocer’. The LCA is beneficial for the
horticultural industry in WA, as this assessment study on strawberry,
mushroom, and lettuce have never been conducted in WA
and specifically altered to suit WA agricultural environment.
The aim of this research is to assess the life cycle GHG emissions
of three fresh produce (i.e. strawberry, button A. bisporus mushroom,
and romaine/cos lettuce). The specific tasks to carry out this
research are as follows: a) assessing the global warming impact of
strawberries, mushrooms, and lettuces using a LCA method; b)
identifying the ‘hotspots’ or the inputs or processes emitting the
highest amount of GHG during the life cycle of a product; and c)
suggesting possible GHG mitigation strategies.
2. Methodology
The LCA follows the ISO 14040:2006 guidelines (ISO, 2006) and
is divided into four steps: (1) goal and scope definition; (2)

M.G.A. Gunady et al. / Journal of Cleaner Production 28 (2012) 81e87 83
inventory analysis; (3) impact assessment and (4) interpretation
(as presented in the ‘Results and discussions’ section of this paper).
2.1. Goal and scope
The current LCA is best termed as streamlined LCA as it does not
take into account the two extremes of the produce life cycle
(Todd and Curran, 1999). This LCA analysis considered up to the
transportation of produce to retail outlet, which does not include
the storage of produce in the retail outlet. Also it does not consider
the consumption stage (e.g. use of refrigerator at home) and the
disposal of produce waste (e.g. left over, skins in the bin) into
landfill (possible methane emissions etc.).
According to Todd and Curran (1999), the process of streamlining
can be viewed as an inherent element of the scope-and-goal
definition process. In this research, the goal of the project was to
determine the life cycle greenhouse global warming impact from
the production of three different produce (i.e. strawberries,
mushrooms, and lettuces) grown in Western Australia. This was
achieved by establishing the functional unit, selecting the relevant
system boundaries, and determining data requirements. For all
three produce, the system boundary included pre-farm, on-farm,
and post-farm stages. The functional unit was 1 kJ of nutritional
energy equivalent of strawberries, cos lettuces, and white button
mushrooms. We examined the nutrition information panel of each
produce in order to obtain the energy content (Self Nutrition Data,
2009). The mass values per 1 kJ food are 0.746 g, 1.090 g, and 1.380 g
for strawberries, mushrooms, and lettuces respectively. The same
functional unit was chosen for all three produce as a basis for
comparison; the energy basis was chosen as it provides a convenient
means of standardizing different fruits and vegetables based
on one of the functions of the food i.e. to deliver energy to the
consumer. Different fruits and vegetables differ significantly in
their energy density and the use of kJ as a functional unit allows us
to correct for such differences.
The functional unit in fact determines the system boundary or
the scope of the work. The system boundary for determining the
global warming potential of the production of 1 kJ (kilojoule)
equivalent nutritional value of lettuce, strawberry and mushroom
production in south-western Australia considered a ‘grower to
grocer’ approach (Fig. 1). The grower to grocer approach takes into
account inputs (e.g., fertilizer, pesticides, electricity) of the three
stages of product life cycle: pre-farm, on-farm and post-farm.
Pre-farm stage takes into account the emissions from the
production and transportation of inputs to paddock, such as N
fertilizer, pesticides and diesel.
On-farm stage includes emissions from farm machinery operations,
and N 2 O emissions from N-fertilizer application due to
production of three produce in Western Australia.
The post-farm stage included emissions from transportation,
packaging, storage and distribution of these products to grocer.
There were some restrictions on the scope of the study which
arose from difficulties involved in accounting for some inputs and
limitations on data availability. Firstly, the manufacture and
construction of all buildings and infrastructures were omitted, as is
common in LCA studies. Secondly, since there are no N 2 OeN
emission factors available for the growth of fresh produce in
semi-arid Western Australian soils (especially irrigated soil), the
analysis has used the default Australian data provided by
the Department of Climate Change in Australian Methodology for
the Estimation of Greenhouse Gas Emissions and Sinks 2006
Agriculture (Department of Climate Change, 2006). Thirdly, generic
libraries entitled, “pesticides and agricultural chemicals”, for some
of the chemicals (e.g. fungicide, insecticide, pesticide, etc) were
used as some of them were unavailable from the Australian database.
Fourthly, it would have been useful to consider other
Australian states as the climatic conditions and soil types vary
across the region, which was not possible due to time constraints.
Fifthly, there are other environmental impacts, such as euthrophication,
acid rain, eco-toxicity, water pollution, which can result
from the production of these three types of produce (Adler et al.,
2007), however, only global warming impacts has been considered
because of governments recent climate change policy (Carbon
pricing) and Australia’s commitment for meeting GHG emission
targets (The Australian, 2011). Sixthly, the omission of discarded
transit packaging such as wooden pallets and plastic wrappings,
and instead only considered primary and secondary packaging
wastes. The wooden pallets were not considered waste as they
were reused and plastic wrapping was not included because it had
not been discarded at the point of delivery where the study
concluded. However, all farm machineries were included due to
their relatively short life-span and high maintenance requirement.
Finally, the use of 1996 factors for converting GHGs to equivalent
amount of CO 2 could result a slight variation in the results than
what could have been obtained using 2007 factors.
2.2. Life cycle inventory
The life cycle inventory (LCI) considers all the relevant inputs and
outputs for processes that occur during the life cycle of a product. The
life cycle was divided into three stages: pre-farm, on-farm, and postfarm.
The process data for these three stages were collected directly
from local strawberries, lettuces, and mushrooms growers in
Western Australia through face to face interview using a prestructured
questionnaire. The data was collected by survey in early
spring between August 27 and September 3, 2010.
The growers were interviewed in person and given a participants
consent form to sign. The growers were given a prestructured
questionnaire to complete which helped to develop
the LCI. This data survey was carried out in Casuarina for mushroom,
Bullsbrook for lettuce and Baldivis for strawberry all of which
are located within 50 km of Perth, Western Australia; being a mild
Mediterranean climate. For each produce one medium commercial
farm was selected being representative of commercial farms in the
region.
Table 1 shows the life cycle inventories of the production and
distribution of 0.3 g of strawberry, 0.5 g of lettuce and 0.5 g of
mushroom at different stages i.e. pre-farm, on-farm, and post-farm.
Fig. 1. System boundary for GHG LCA on a grocery level.

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M.G.A. Gunady et al. / Journal of Cleaner Production 28 (2012) 81e87
Table 1
Life Cycle Inventories of three types of produce: Strawberry, mushroom and lettuce.
LCI of 0.3 kg
strawberry
LCI of 0.5 kg
mushroom
LCI of 0.5 kg
lettuce
Inputs Value Unit
Pre-farm
Pesticide 2.17 10 4 kg
Fungicide 4.47 10 5 kg
Calcium nitrate 5.75 10 3 kg
Potassium nitrate 8.4 10 3 kg
Monoammonium phosphate 1.58 10 3 kg
Farm machinery 0.045 USD a
Magnesium sulfate 8.0 10 4 kg
Transportation of
4.13 10 2 tkm
chemicals by road
On-farm
Farm machinery operation 30.6 MJ
Irrigation 0.3 kg
Nitrous oxide emission 2.6 10 3 kg
Post-farm
Transportation to district center 0.00051 t km
Storage 0.17 kW h
Transportation of Booragoon 0.00435 t km
Transportation to Broome 0.66 t km
Pre-farm
Farm machinery 1.73 10 5 USD a
Mushroom compost 6.34 10 4 Tonne
Transportation of compost
By sea 25.7 t km
By road 9.2 t km
On-farm
Detergent 4.22 10 5 Kroner a
Farm machinery 1.05 10 3 MJ
Pasteurizer 2.94 10 2 kW h
Post-farm
Grading and sizing 4.74 10 4 kW h
Packaging 1.21 10 3 kW h
Cold storage 1.07 10 4 kW h
Transport to cold storage 5.1 10 4 tkm
Methane emission from
1.09 10 4 kg
cardboard in landfill
Transportation of Booragoon 7.25 10 3 tkm
Transportation to Broome 1.1 t km
Pre-farm
Farm machinery 0.4 USD a
Compost 1.22 10 4 tonne
Ammonium nitrate 3.83 10 3 kg
Active pesticide 1.56 10 4 kg
Herbicide 0.29 USD a
Organic fertilizer 1.67 10 2 kg
Transportation of
3.05 10 2 tkm
chemicals by road
On-farm
Farm machinery operation 88.5 MJ
Irrigation 2.83 kW h
Nitrous oxide emission 2.1 10 3 kg
Post-farm
Packaging 1.21 10 3 kW h
Storage 3.34 kW h
Transportation to
5 10 3 tkm
distribution center
Transportation of Booragoon 7.25 10 3 tkm
Transportation to Broome 1.1 t km
a A USA inputeoutput database 1998 and a Danish inputeoutput database
1999 were used to assess the GHG emitted from manufacturing of farm
machinery, herbicide and detergent respectively (Nemecek et al., 2004; Weidema,
2005). The USA and Danish databases contain environmental emission data for
the production of US$ 1 equivalent farm machinery, US$ 1 equivalent herbicide
and DKK 1 (Danish Kroner) equivalent detergent, respectively. The current prices
of farm machinery, herbicide and detergent were deflated at 3% per year to 1998
and 1999 prices (in AUD) for farm machinery and detergent, respectively.
Following this, the 1998 price of machinery in AUD/machinery has been converted
into 1998 US dollar by multiplying by 0.6 and the 1999 price of detergent/
kg were converted into 1999 DKK by multiplying by 4.4.
These process data or input values were used to calculate the inputs
required to produce the amounts of strawberry, lettuce and
mushroom providing 1 kJ equivalent of nutritional value. In the prefarm
stage, data for generic materials was collected such as:
transportation and production of chemicals and machinery, transportation
of packaging, and transportation of raw materials in the
case of mushrooms such as peat, spawn, and compost. On farm
activities included information on inputs, such as amount of agricultural
chemicals used, diesel combustion by machinery, the
amount of waste generated, amount of water utilized for irrigation,
as well as electricity and energy consumptions. Lastly, the postfarm
stage included transport of produce to the Distribution
Center (DC), storage of produce in DC, and transport to retail
outlets. It is important to note that the pallets were not waste as
they were reused and so the emissions associated with their
degradation in the landfill were not considered and also the plastic
was not waste at the point of delivery where the study ended.
2.3. Impact assessment
The impact assessment assesses the global warming potential
based on the inventory analysis. The life cycle GHG emissions of
strawberries, lettuces, and mushrooms production for pre-farm, onfarm,
and post-farm involved two steps (Biswas et al., 2010, 2008):
(1) calculating the total gases produced in each process and (2)
converting the emitted gases to CO 2 equivalent GHG emissions.
Step 1. The process data from the LCI were inserted into Simapro
7.1 (Pre Consultants, 2008) software to calculate the GHG emissions
associated with the production of 1 kJ of strawberries, lettuces, and
mushrooms. The input/output data of the LCI were linked to
respective libraries in Simapro 7.1. The library is a database that
consists of energy consumption, emission, and materials data for
the production of one unit of a product. The units of input and
output data of the LCI depend on the unit of the relevant materials
(i.e. kg, liter, MJ, $, etc).
Libraries for chemicals: The Australian Unit Process Life Cycle
Inventory (Royal Melbourne Institute of Technology, 2007) was
used to calculate GHG emissions from the production of chemical
inputs such as pesticides and herbicides. As some of the chemicals
were unavailable from the Australian database, generic libraries
were used instead. The supply chain for the fertilizers, herbicides,
and pesticides including production and transportation to the point
of use (or paddock) was incorporated in order to assess the GHG
emissions during the pre-farm stage. Since there is no library for
mushroom compost available, a local mushroom compost farm was
contacted to determine the energy requirement in order to produce
mushroom compost and the emission factor for mushroom
compost production was derived from this energy value (Powe’s
Mushroom Compost, 2010, pers. comm.).
Library for transportation: Table 1 illustrates the transportation
required to carry inputs/raw materials from pre-farm to paddock
(on-farm) and to carry produce from farm (paddock) to DC and retail
outlets. The unit for transport is tonne-kilometer (t km). For example,
a medium size taut liner truck traveled 53 km to carry fungicide to
the strawberry farm. In this case 0.053 t km is required to carry 1 kg of
fungicide for 53 km (i.e. 0.001 t 53 km). GHG emissions from
transportation were equivalent to 0.076, 86 10 4 and 13 10 4 kg/
tkmofCO 2 ,CH 4 , and N 2 O respectively (Biswas et al., 2008).
Farm machinery library: The USA inputeoutput database was
used to assess the GHG emitted from the manufacture of farm
machinery. This database contains environmental emission data for
the production of US $1 equivalent farm machinery. The current
price of farm machinery was deflated to a 1998 price (in AUD) at 3%
per year. Following this, the 1998 price of machinery in AUD/

M.G.A. Gunady et al. / Journal of Cleaner Production 28 (2012) 81e87 85
hectare has been converted into 1998 US dollars (by multiplying by
0.6) (Suh, 2004).
Farm machinery operation library: Farm machinery that
consumes less than 500 MJ/ha is regarded as light duty machinery
(Nemecek et al., 2004). Thus, the library for light duty agricultural
machinery was used to calculate the potential GHG emitted from
farm machinery operation. The emission factors were obtained
from RMIT’s LCA database (Royal Melbourne Institute of
Technology, 2007).
Electricity library: The library for Western Australia electricity
generation mix (Royal Melbourne Institute of Technology, 2007)
was used to calculate GHG emission from electricity generation due
to various activities such as: irrigation, storage, pasteurization and
sterilization (in mushrooms).
Packaging library: Packaging made from BOPP film for lettuces
and A250-B punnet, in recycle PET, 105 mm 95 mm 57.5 mm for
strawberries. There is no database for Biaxially Oriented PP (BOPP)
in the Simapro software or the literature so far reviewed, Australian
Database (Royal Melbourne Institute of Technology, 2007) for
polypropylene was used to calculate the GHG emissions from
packaging materials. Polypropylene is a raw material for BOPP
production. The exclusion of emission associated with the conversion
of polypropylene to BOPP could underestimate the total carbon
footprint to some extent.
Step 2. After linking the inputs/outputs to the relevant libraries,
Simapro software calculated the GHG emissions by converting each
selected GHG to CO 2 equivalent. The program sorted GHG from the
selected libraries and then converted each selected GHG to CO 2
equivalent (or gram CO 2 equivalent). Following IPCC’s second
assessment report (SER) (IPCC, 1996), it was considered that the
CH 4 is 21 times and N 2 O is 310 times more effective at trapping heat
in the atmosphere compared to CO 2 over a 100-year time. Lastly, all
CO 2 equivalent GHG emissions for all life cycle inventory items
were added to determine the full life cycle GHG emissions associated
with production of strawberries, mushrooms, and lettuces.
Since no salable co-products were produced from these three
types of produce, the allocation method was not applied to allocate
GHG emissions to produce and co-product.
3. Results and discussions
3.1. GHG emissions from strawberries, lettuces, and mushrooms
production
Fig. 2 illustrates the carbon footprint (in CO 2 equivalent) of 1 kJ
energy value of strawberries, lettuces, and mushrooms production.
The equivalent of 2.458, 3.000, and 5.180 g of CO 2 equivalent were
emitted due to the production of 1 kJ equivalent of strawberries
(0.746 g), mushrooms (1.090 g), and lettuces (1.380 g) respectively.
Pre-farm stage of strawberries contributed 14% (0.343 g CO 2
equivalent) of the total GHG emissions, on-farm accounted for 54%
(1.322 g CO 2 equivalent), and post-farm contributed 32% (0.793 g
CO 2 equivalent) of the total GHG emissions. Similar streamlined LCA
study on strawberries in Japan found to have higher GHG emissions
when compared to this study (4.13 g CO 2 equivalent compared to
2.4 g CO 2 equivalent per 1 kJ nutrition energy equivalent strawberries
produced) (Yoshikawa et al., 2008). This is because in the
Japanese study, strawberries were grown in greenhouses and thus
required more energy and also because the study covered more
stages by including consumption and disposal stages as well.
The pre-farm, on-farm, and post-farm stages of lettuces emitted
approximately 13% (0.665 g CO 2 equivalent), 48% (2.497 g CO 2
equivalent), and 39% (2 g CO 2 equivalent) of the total GHG emissions.
In an LCA study on lettuces grown in greenhouses conducted by
gram CO 2 -e/kJ
3.00
2.50
2.00
1.50
1.00
0.50
0.00
Pre-farm On-farm Post-farm Transport
Strawberry 0.34 1.32 0.63 0.17
Mushroom 1.60 0.74 0.50 0.17
Lettuce 0.67 2.50 1.83 0.19
Hospido et al. (Hospido et al., 2009), 3.75 g CO 2 equivalent of GHG
was emitted from the production and distribution of 1 kg of lettuces
in UK. For comparison purpose, the result obtained in this study was
converted to 1 kg basis and similar amount of CO 2 equivalent was
obtained (3.56 g CO 2 equivalent). Higher amount of CO 2 equivalent
in UK grown lettuces was predicted due to the more intensive energy
required to heat the glasshouses during colder months.
During the life cycle of mushrooms, 52% (1.597 g CO 2 equivalent)
of GHG emissions was emitted during pre-farm stage, 25% (0.738 g
CO 2 equivalent) during on-farm stage, and 23% (0.667 g CO 2
equivalent) during post-farm stage. In the case of mushrooms, no
other similar LCA studies have been carried out to compare with.
Among the three produce examined, lettuce production has the
highest overall carbon footprint for several reasons. Firstly, they
have the lowest energy value, which means in order to provide 1 kJ
of energy, more lettuces by mass are required when compared to
strawberries and mushrooms. Secondly, the lettuce supply chain in
this study involved an additional step, in which lettuces were sent to
packing house; therefore more energy and fuel were required for
packing and storage, and for transportation respectively. The highest
GHG emission during the pre-farm stage of mushrooms was due
to transport of raw materials such as peat, compost, and spawn. The
lowest on-farm emission from mushrooms production was due to
minimal machinery utilization as the industry is very labor intensive
(every single mushroom is handpicked); whereas strawberries and
lettuces require intense machinery operation especially during
cultivation. Thus it is explaining the high GHG emissions during onfarm
activity of strawberries and lettuces production.
3.2. Identification of hotspots
Strawberry Mushroom Lettuce
Fig. 2. GHG emissions (gram CO 2 equivalent) for 1 kJ strawberry, lettuce, and mushroom
production.
Table 2 illustrates the percentage contribution of GHG emissions
from different inputs during lettuces, mushrooms, and strawberries
production. In strawberry production, agricultural machinery
operation has been identified as the ‘hotspot’ which accounted for
58% of the total GHG emissions, followed by chemical-fertilizer use
(23%), particularly from fertilizer and electricity (12%). The transportation
of strawberries to the Distribution Center (DC) does not
seem to have a significant global warming impact. Similarly,
Maraseni et al. (2010) found that the GHG emissions due to farm
machinery operation are directly related to fossil fuel consumption,
while the GHG emitted from transporting the inputs are usually
negligible. Similar to strawberry production, in romaine/cos lettuce
production, the hotspot was agricultural machinery operation,
which accounted for 52% of the total GHG emitted. The second

86
M.G.A. Gunady et al. / Journal of Cleaner Production 28 (2012) 81e87
Table 2
Contribution of inputs to GHG emissions (gram of CO 2 equivalents) from the
production of 1 kJ nutritional value equivalent of: a) strawberry; b) romaine/cos
lettuce and c) button mushroom.
Inputs g CO 2 -e/kJ 100%
Strawberry
Agricultural machinery operation 1.43 58%
Use of N-fertilizer 0.57 23%
Electricity 0.29 12%
Production of farm inputs 0.12 5%
Transport 0.05 2%
Total 2.46 100%
Romaine/cos lettuce
Agricultural machinery operation 2.71 52%
Electricity 1.14 22%
Use of N-fertilizer 0.73 14%
Transport 0.34 7%
Production of farm inputs 0.26 5%
Total 5.18 100%
Mushrooms
Transport of compost and spawn 2.1 70%
Air transport of peats 0.3 11%
Electricity for storage 0.24 8%
Transportation for distribution 0.15 5%
Pasteurization 0.09 3%
Sanitizing 0.09 3%
Total 3.00 100%
highest contributor of GHG emissions was electricity and energy
required for packing and storage of produce, followed by agricultural
chemical use (14%). Strawberry and lettuce production are
highly mechanized, which require intensive machinery operation
especially during cultivation thus explaining the high GHG emissions
from agricultural machinery operations. Transport of raw
materials was the highest contributor of GHG emissions in mushroom
production, with 70% coming from transport of spawn and
compost, while transport of peat from overseas made up 11% of the
net GHG emissions. Compost which was made of chicken manure
and straw was transported regularly from the compost yard located
approximately 46 km from the mushroom farm. Peat is transported
from Germany, Canada, and Ireland once every two weeks using sea
containers. Additionally, electricity during mushroom production
contributed 8% of the total GHG emissions, while the rest of the
activities were just minor contributors.
3.3. Mitigation strategies
According to Table 2, agricultural machinery operation appeared
to be the ‘hotspot’ in strawberry and lettuce production due to the
intensive use of machinery especially during cultivation. A reduction
in GHG emissions from farming machinery operation could be
obtained by using alternative fuels where possible. Beer et al.
(2002) compared the emissions of GHG from Australian heavy
vehicles using several alternative fuels with the results indicating
that biodiesel and ethanol produced the lowest GHG emissions,
followed by liquid petroleum gas (LPG). Biodiesel is a renewable
resource that can be produced from agricultural oils or animal fats
and alcohol (such as methanol or ethanol). For example, oil
produced from canola or other oil bearing seeds plants can be
potentially utilized to produce biodiesel in Australia (Beer et al.,
2002). Moringa oleifera, for instance, is a perennial tree species
widely grown in WA that could be more beneficial to produce
biodiesel when compared to canola as M. oleifera can reduce the
pressure on canola oil for food demands (Biswas and John, 2008).
However, other environmental impact categories need to be
considered when assessing the use of biodiesel, as De Nocker et al.
(1998) found biodiesel use impacted more on soil and water
acidification, eutrophication, and radioactive waste type (i.e., other
environmental impact categories) than use of diesel.
Additionally, Nemecek et al. (2004) has suggested that when
selecting farming machinery, consideration should be given to its
ability to perform numerous tasks, as multi-functional machinery
can provide improved efficiency. Nemecek et al. (2004) also
mentioned the importance of maintaining machinery in good
working order in order to improve fuel efficiency.
As for mushroom production, transport of peat, spawn, and
compost has been identified as the “hotspot” due to the intensity
and the distance traveled to deliver the raw materials. O’Halloran
et al. (2008) suggested reducing the distance of the raw materials
transported, and this can be achieved by using local peat instead of
importing from overseas, although local peat must have the
required characteristics to ensure good quality mushrooms and be
cost effective. If reducing the distance traveled is not an option,
then another alternative is to use the most energy efficient and low
GHG emitting fuels in transport. Another consideration is
attempting to load the containers to full capacity and to have
a return load to reduce the GHG emissions per unit of product
transport.
The application of N-fertilizer was the second highest contributor
to GHG emissions in strawberry production, therefore it is
important to ensure precision farming systems which could
potentially reduce the use of fertilizer by one-third (Flynn, 2009).
Alternatively, substituting chemical fertilizer for organic fertilizer,
such as animal manure, crop residue, nitrogen fixing crop, has been
shown to be an important mitigation option due to its lower N 2 O
emissions and nitrogen input (Flynn, 2009).
Although electricity was the second “hotspot” in lettuce, and the
third largest for strawberry and mushroom production, it was
a significant contributor to the emission of GHG for all three
produce. Taking advantage of existing renewable energy sources
such as: solar power or wind generated electricity and simulatinghuman
intelligent control method for energy conservation in the
storage system can greatly reduce the emissions of GHG (Nemecek
et al., 2004; Kaisheng et al., 2009). Additionally, by converting
organic residue to biogas for electricity generation to replace the
fossil fuel generated grid electricity (Biswas and Lucas, 1997).
4. Conclusions and recommendations
There is potential for reducing the impact of fresh produce on
global warming by conducting LCA.
An LCA was carried out to identify the GHG emissions during
different stages of strawberry, romaine/cos lettuce, and button
mushrooms production. Lettuces have been found to have the
highest GHG emissions (5.18 g of CO 2 equivalent) when compared
to strawberries and mushrooms due to mass required to produce
1 kJ of energy and the additional packing house step.
The results show the significance of pre-farm practices on
mushroom’s GHG emissions (1.6 g CO 2 equivalent) and on-farm
practices on strawberry (1.32 g CO 2 equivalent) and lettuce
(2.5 g CO 2 equivalent) GHG emissions. Transport of raw materials
such as peat, compost, and spawn has been identified as the ‘hotspot’
(81% of the total GHG emissions) in mushroom production
due to a great distance the raw materials have to travel to reach the
farm. Agricultural machinery operation has been identified as the
‘hotspot’ in lettuce (53% of the total GHG emissions) and strawberry
(58% of the total GHG emissions) production due to the intensive
machinery use; especially during cultivation.
Strategies for managing strawberry and lettuce, where agricultural
machinery operation was the ‘hotspot’ include the use of
alternative or renewable fuels such as biodiesel and conventional
fuel such as LPG to reduce life cycle GHG emissions. Regular servicing

M.G.A. Gunady et al. / Journal of Cleaner Production 28 (2012) 81e87 87
and maintenance of farm machinery also helps maintaining the
efficiency of that machinery. A strategy for managing mushroom
production includes reducing the distance that the raw materials are
transported in order to lower GHG emissions. This can be achieved
by substituting imported peat with local peat. Another strategy
could be to load the containers to full capacity and to have a return
load to reduce the GHG emissions per unit of product transport.
Interestingly following completion of our study the finding with
lettuce that the additional packing house step resulted in increased
GHG emissions has now resulted in the grower installing packing
facilities on farm in an effort to reduce these emissions.
Finally, the same framework can be applied to estimate the
carbon footprint of other fresh produce that will assist in the
development of the Australia’s future carbon trading scheme.
Acknowledgment
This research was supported by Craig Charles, fresh produce
quality manager Coles Supermarket Group Western Australia and
the Western Australia growers.
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