LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

GROUP 6, SESSION B: METHODS, TOOLS, DATABASES 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
179. Determining greenhouse gas emissions profiles for Australian
agricultural products at a regional scale: methodological opportunities
and obstacles
Philippa M Brock 1,* , Phillip Graham 1 , David F Herridge 2 , Patrick Madden 1 , Graeme D Schwenke 1
1 Department of Primary Industries, New South Wales, Australia, 2 University of New England, New South
Wales, Australia, Corresponding author. E-mail: pip.brock@industry.nsw.gov.au
Life Cycle Assessments (LCAs) of greenhouse gas emissions associated with agriculture have commonly
been conducted at a farm scale (case study) or emissions are calculated at a national scale. However, until
recently, there has tended to be a scarcity of regionally-applicable assessments. This may be partly due to
difficulties in obtaining representative data that account for variability in agricultural production systems.
However, for national policies to be regionally applicable and for landholders to identify opportunities for
practice change, it is essential that inter- and intra-regional differences be better understood. We contend that
by accommodating variability, highly robust regional LCAs can be built and that this broader analysis will
improve our understanding about the representativeness of existing case-studies.
We have found the greatest opportunity for emissions reduction in cropping systems to be replacing synthetic
nitrogenous fertilisers with biologically fixed N, with emissions from a legume-based system found to be
33% of those from a non-legume system (Fig. 1; Table 1). Other factors which greatly influence calculated
emissions per unit of product are yield variation across seasons and the choice of direct nitrous oxide emissions
factor (Brock et al. accepted; Herridge et al. 2011; Schwenke et al. 2011). We have also found variability
in emissions from sheep enterprises, ranging from 39% reduction for change in enterprise emphasis from
wool to meat production (Table 2), to approximately 28% variability for change in wool price or calculation
method, to 23% variability for change in fibre diameter, to 10% variability for change in fleece weight
(Brock et al. in preparation.; Graham et al. 2010).
To account for this variability, we are:
1. obtaining regional-level data, including measures of variability, from research and extension staff
2. providing detailed documentation about the variables and discussing other environmental effects
3. testing the sensitivity of the emissions profile by changing the parameter values for formulas constructed
in SimaPro and checked against FarmGAS
4. applying data from instrumented regional field trials
5. testing the effect of changes in economic allocation in animal production systems
6. using data from modelling packages, such as GrassGro, to compare long and short term variability.
The variability associated with many LCA inputs and lack of enterprise-level seasonally-specific data makes
farm-scale (case-study) assessment problematic. It seems highly desirable for there to be greater focus on
regional-scale LCA, to support both testing of national policies and on-farm emissions reduction.
References
Brock, P., Madden, P., Schwenke, G., Herridge, D. Greenhouse gas emissions profile for 1 tonne of wheat
produced in Central Zone (East) New South Wales: A Life Cycle Assessment approach. Crop and Pasture
Science, accepted.
Brock, P., Graham, P., Madden, P. Greenhouse gas emissions profile for 1 kg of wool produced in the Yass
Region, New South Wales: A Life Cycle Assessment approach. Animal Production Science, in prep.
Graham, P. 2010. Bookham Grazing Demonstration Results. Department of Primary Industries, Yass NSW.
Herridge, D., Schwenke, G., Brock, P. 2011. Nitrogen-fixing chickpea underpin productive, sustainable
farming systems in Australia’s Northern Grains Region. Proceedings of the 25th Latin American Conference
on Rhizobiology, 9 Sep 2011, Uruguay.
Schwenke, G., Brock, P., Herridge, D. 2011. Nitrogen-fixing legumes in farming systems reduce greenhouse
gas emissions. Proceedings of the 17th International Congress on Nitrogen Fixation, 27 Nov - 1 Dec,
Fremantle, Western Australia.
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