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

PARALLEL SESSION 7B: BEEF PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
specific IPCC Tier 2 approach used in Australia’s national GHG inventory, taking into account herd structure
on a daily time step, feed quality and growth rate. The Australian national GHG inventory methods were
also applied in relation to emissions from agricultural soils as a result of inorganic nitrogen fertiliser application
and the residue of cultivated leguminous pastures. Recent land use change (deforestation) was not a
feature of any of the systems and possible changes in soil carbon were ignored due to a lack of relevant data.
Data relating to GHG emissions associated with electricity, fuels (used on farm and in transportation processes),
fertiliser production, supplementary feeds (grain, pasture hay and feedlot ration) and veterinary products
were obtained from various Australian database sources. To calculate the carbon footprint, the latest
100-year global warming potentials for GHGs published by the IPCC were used.
2.3. Water footprint modelling
The water footprint modelling was based on consumptive water use only, as a recently developed method
integrating consumptive and degradative water use into a single indicator was not available at the time (Ridoutt
and Pfister, 2012). A complete description of the water flows quantified is presented in Ridoutt et al.,
(2012). In summary, the inventory included flows from surface and groundwater into the farming system to
irrigate pastures as well as crops used for supplemental feeding on farm and in the feedlot. Secondly, it included
the reduction in flows from the farming land base to surface and groundwater as a result of the operation
of farm dams used for livestock watering. Thirdly, it included direct water use in feedlot operations.
Finally, it included water use associated with the production of inputs to the farming and feedlot operations.
The indicator results, in the units L H2Oe, were calculated by multiplying each spatially differentiated instance
of water use by the locally relevant WSI and dividing by the global average WSI (0.602).
2.4. Land use footprint modelling
For each beef cattle production system, an inventory of geographically-defined agricultural land use was
compiled. The land use types were unimproved pasture, non-irrigated improved pasture, irrigated improved
pasture and cropland. The inventory excluded land use associated with the built environment (e.g. roads,
factories) and land use associated with the extraction of resources from nature (e.g. mining of rock phosphate,
extraction of oil). Land use was expressed in the unit m 2 .yr, taking into consideration the duration of
occupation. Land was considered to be occupied if it was unavailable for other productive purposes. As such,
single cropping systems, which are prevalent in Australia, were deemed to occupy the land for the complete
year, even if production only occurred during part of the year. The inventory did not include situations of
multiple land use, such as mixed grazing of livestock, recreation and timber production, meaning that land
use was completely attributed to agricultural production. On the basis that biodiversity is largely reduced by
intensive agricultural production systems (Pfister et al., 2011), no attempt was made to describe the remaining
ecological value of the land.
For land use footprinting, the net primary productivity of potential biomass (NPP0, g C.m -2 .yr -1 ) was used
to describe the intrinsic productive quality of land. Our reasoning is that the occupation of high-NPP0 land
exerts more pressure on global land resources than the occupation of low-NPP0 land. This is obviously a
simplification as factors in addition to NPP0 determine the desirability of land in terms of human development.
However, NPP0 is a useful starting point and it is an objective measure for which global datasets exist.
Land use footprint indicator results were calculated by multiplying each spatially-differentiated instance of
land use (m 2 .yr) by the relevant NPP0 associated with each land use type in each area, and dividing by the
global average NPP0. The indicator results were expressed in the reference unit m 2 .yr-e, where 1 m 2 .yr-e
represents 1 m 2 of land occupation for 1 year at the global average potential net primary productivity. To
perform the assessment, land use maps were obtained from the Australian Government Bureau of Rural Sciences
(resolution 1 km) and NPP0 values at a resolution of 5 arc min were obtained from Haberl et al.,
(2007).
2.5. Normalisation
To assist in interpretation of the life cycle impact category indicator results, normalisation was performed,
which is the step involving comparison of indicator results to a common reference situation. In this study, the
chosen reference was the global economic system in the years 1995-2000 and results are reported in person
equivalents. The land use footprint of humanity was calculated using data reported in Haberl et al., (2007)
and Erb et al., (2007). To be consistent with the method of calculation of land use footprints described above
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