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

GROUP 1, SESSION A: ANIMAL PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
14. A matrix approach to spatialise impacts of US milk production
Anne Asselin-Balençon 1,* , Andrew Henderson 1 , Marty Heller 1,3 , Lindsay Lessard 2 , Samuel Vionnet 2 ,
Sebastien Humbert 2 , Rosie Saad 4 , Manuele Margni 4 , Greg Thoma 5 , Marty Matlock 6 , Olivier Jolliet 1
1 School of Public Health (SPH), University of Michigan, 6622 SPH Tower, 1415 Washington Heights, Ann
Arbor, Michigan 48109-2029, USA, 2 Quantis, Parc scientifique de l'EPFL, Bât. D, 1015 Lausanne Switzerland,
3 Center for Sustainable Systems, School of Natural Resources and Environment, University of Michigan,
3012 Dana Building, 440 Church Street, Ann Arbor, MI 48109-1041, USA, 4 CIRAIG, École Polytechnique
de Montréal, Département de génie chimique, C.P. 6079, succ. Centre-Ville, Montréal (Qc) Canada,
H3C 3A7, 5 Ralph E. Martin Department of Chemical Engineering, University of Arkansas, 3202 Bell Engineering
Center, 800 West Dickson Street, Fayetteville, AR 72701-1201, USA, 6 Department of Biological &
Agricultural Engineering, Engineering Hall, Fayetteville, AR 7270, USA, Corresponding author. E-mail:
aasselin@umich.edu
In many cases in production, goods are not consumed in the same place they are produced. This is particularly
the case in agriculture. Crops are produced for a lot of purposes, which can be milk or meat production
or processing for human consumption. The downstream production (eg milk or meat) does not necessarily
take place in the same location where the crops were grown; some of those crops can be transported over
very long distances before being consumed or processed. This is especially the case in the case of US milk,
where corn grain for example is mostly produced in the Corn Belt, while it is consumed all over the nation.
On the other end and for some impact categories the impacts of crop production is very local. It is the case of
water stress for example. Crop production is a water intensive activity, and water use and impacts vary
greatly depending on region, crop irrigation and type of crop. In some regions, irrigation account for up to
90% of water withdrawn from available sources, while in some others with plentiful rainwater, irrigation is
barely necessary.
This presentation introduces a generic model to properly account for the attribution of a flow or impact to the
milk producing locations and grain producing locations, through a matrix approach at the state level. This
approach allows an analysis in which an inventory flow in milk producing state j can be decomposed into
inventories flows in grain producing states i. Furthermore, impacts from those grain and milk producing
states are aggregated on the level of the inducer (the state producing milk, for which grain is grown in other
states), the emitter (the states in which environmental emissions occur), or receiver (the states or other global
regions in which the impacts of those environmental emissions are felt).
Overall, the water stress impact of 1 kg milk in the US is equal to 109 litres in competition per kg milk, California
representing 22% of the national milk production and 54% of the impact. This national impact incorporates
the impact of each of the feeds at a state resolution. Looking at a particular feed production, corn
grain, the national water impact is 54 litres in competition per kg corn grain, nearly half of this impact coming
from one single state, Nebraska, combining two factors: relatively high production and relatively high
water stress index. The impact of eutrophication from phosphorus takes place over the whole watershed
downstream of crop production and application of organic and inorganic P fertiliser. The original matrix
approach is key to correctly assess local impacts of a given industry accounting for the origin of its supplies,
and can be used for different spatialised resolutions and industries.
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