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

GROUP 2, SESSION A: CARBON OR WATER FOOTPRINTS, SOIL, BIODIVERSITY 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
61. A method for estimating water use in food supply chains: liquid
milk as an example
Stefan Hörtenhuber 1,2,* , Rainer Weißhaidinger 1 , Thomas Lindenthal 1,3 ,Werner Zollitsch 2
1 Research Institute of Organic Agriculture (FiBL) Austria, 2 University of Natural Resources and Life Sciences
Vienna, Department of Sustainable Agricultural Systems, 3 University of Natural Resources and Life
Sciences Vienna, Centre for Global Change and Sustainability, Corresponding author. E-mail:
stefan.hoertenhuber@fibl.org
A water-use (WU) method, based on Hoekstra et al. (2009), was modified and applied to Austrian agriculture,
particularly livestock production. To meet the requirements of a life cycle assessment (LCA) approach,
system boundaries include additional demand for water, e.g. from dairies, trade, supply of production inputs
(mineral fertilisers) or for industrial processing of feedstuffs. The WU method accounts for effective or so
called ‘blue’ water demand which is needed for irrigation, cleaning, livestock‘s drinking water or for cooling
systems in dairies. Precipitation water which is evapotranspirated is summarised within the ‘green’ water,
including a potential loss of precipitation in the case of preceding clearing of tropical forests. The WU
method provides regionally differentiated water demand for effective evapotranspiration per kg yield for
roughage, concentrates (grains, grain legumes, oilseeds or co-products from oil mills and distilleries) or bedding
material, which is not only based on precipitation inputs but also reflects climatic and soil conditions,
groundwater recharge and run-off. ’Grey’ water partly integrates an eutrophication potential into the water
footprint. For derivation of the grey water (i.e. dilution below nitrate limits 45 mg NO3 per litre in drinking
water), a detailed nitrogen (N) cycle model was used, including various N-inputs and outputs from agricultural
production and its upstream and downstream processes. Co-products (beef from cull cows and calves)
and water required for the rearing phase of dairy cow were also considered (see Hörtenhuber et al., 2010).
Generally, results for livestock products’ WU mainly depend on type (i.e. composition) and quantity of the
diet needed to produce one unit of product (kg milk).
The result for an alpine, grassland-based production system shows an overall water demand of about 940
litres per kg liquid milk at the supermarket (Fig. 1). This WU result agrees with findings from previous studies
for milk, e.g. 800 and 990 litres of water demand (global scale) as reported by Chapagain and Hoekstra
(2003) and Hoekstra and Chapagain (2006), respectively. However, some differences between these sources
and our study are obvious, such as (1) a higher proportion of grey water and (2) a smaller proportion of green
water in our result; (3) additional processes were included, which require water along the entire supply chain.
A potential for the reduction of water demand was identified particularly for ‘grey water’ by implementing
the following measures: (i) greening and catch crops instead of bare fallow, (ii) application of manure/fertiliser
according to the requirement of crops at the optimum point of time, (iii) decreasing the input
of external production factors (mineral fertilisers) or (iv) preferring organic over mineral fertilisers. Because
of the limited water supply in many parts of the world, comprehensive WU or water footprint methods need
to be developed and integrated into sustainability assessment schemes for agricultural products.
References
Chapagain, A.K., Hoekstra, A.Y., 2003. Virtual water flows between nations in relation to trade in livestock
and livestock products. Value of Water Research Report Series No. 13, UNESCO-IHE.
Hoekstra, A.Y., Chapagain, A.K., 2006. Water footprints of nations: Water use by people as a function of
their consumption pattern. Water Resources Management. 21(1), 35-48.
Hoekstra, A.Y., Chapagain, A.K., Aldaya, M.M., Mekonnen, M.M., 2009. Water footprint manual: State of
the art 2009. Water Footprint Network, Enschede, Niederlande.
Hörtenhuber, S., Lindenthal, T., Amon, B., Markut, T., Kirner, L., Zollitsch, W., 2010. Greenhouse gas
emissions from selected Austrian dairy production systems – model calculations considering the effects of
land use change. Renewable Agriculture and Food Systems 25(4), 316-329.
Hörtenhuber, S., Lindenthal, T., Schmid, E., 2011: Water Footprint – Ein Beitrag zur Nachhaltigkeitsbewertung
am Beispiel der Milcherzeugung, in: Proceedings of the 66th ALVA Conference, May 23-24 2011.
Graz, Austria, pp. 87-89.
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