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

GROUP 4, SESSION B: CROP PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
101. Influence of allocation methods in the quantification of the
environmental impacts of compost application
Julia Martínez-Blanco 1,* , Joan Rieradevall 1,2 , Pere Muñoz 3 , Assumpció Antón 3,4
1 Institute of Environmental Science and Technology (ICTA), Universitat Autònoma de Barcelona (UAB),
08193 Bellaterra, Barcelona, Spain, 2 Chemical Engineering Department, Universitat Autònoma de Barcelona
(UAB), 08193 Bellaterra, Barcelona, Spain, 3 Institute of Research and Technology in Agrifood Sector
(IRTA), Environmental Horticulture, 08348 Cabrils, Barcelona, Spain, 4 Departament d’Enginyeria Química,
Universitat Rovira i Virgili (URV), 43007 Tarragona, Spain, Corresponding author. E-mail:
julia.martinez@uab.cat
Fertilisation has been reported as one of the key factors for the environmental performance of horticulture
products, which are often highly nutrient-demanding, particularly for systems of low technology (Antón et
al., 2005; Romero-Gámez et al., 2011). An special case, among fertilisers, is compost. Our previous studies
have indicated that compost fertilisers have higher environmental impacts than mineral ones in some impact
categories when yields are used as reference flow (Martínez-Blanco et al. 2011).
Compost is also known to be a slow-release fertiliser, usually applied for periods of 1-2 years, considering
the nutritional necessities of the annual or biannual crop cycle, in order to avoid individual environmental
burdens of transport and machinery for each crop. Therefore, compost is applied at the beginning of the rotation,
but is supplying nutrients to all the considered crops.
Therefore, when the burdens of compost production and application have to be distributed among the crops
in the cycle, a multifunctional problem arises. According to ISO 14044, wherever possible, allocation should
be avoided by dividing the unit process or expanding the product system. Where allocation cannot be
avoided, the inputs and outputs of the system should be partitioned between its different products underlying
physical relationships, as a first option, or other relationships (e.g. economic value).
Accordingly, the main goal of our study is the comparison of the environmental performance of four crops in
a rotation, which are applying compost and mineral fertilisers, when several methods for compost burdens
distribution are used.
For the study, four experimental Mediterranean crops (chard, tomato, cauliflower and onion) in a rotation are
compared and the reference flow hectare is selected. Three main stages are included within the boundaries of
the system: fertiliser production, transport and cultivation. Most of this data were obtained experimentally in
the fields and the composting plants, by the authors or from previous research of the group (Martínez-Blanco
et al., 2011). When local information was not available, bibliographical sources and the database v2.0 were
used. The environmental assessment is following the obligatory classification and characterisation phases
defined by the ISO 14044 and four mid-point impact categories are considered (acidification, eutrophication,
abiotic depletion and global warming).
Four alternative approaches for compost burdens distribution are compared here: (1) system expansion, i.e.
the impacts of mineral fertilisers avoided due to compost use are subtracted from the total burdens; and three
allocation alternatives (2) according to compost delayed mineralisation; (3) according to nitrogen crop requirements;
and (4) according to economic allocation using cost-benefit values.
Compost burdens distributions are different for the four approaches and thus impact differences with the
mineral fertiliser traditional option, for each one of the crops in the rotation, are detected.
References
Antón, A., Montero, J.I., Muñoz, P., Castells, F., 2005. LCA and tomato production in Mediterranean greenhouses.
Int. J. Agric. Resour. Gov. Ecol. 4(2), 102–112.
Romero-Gamez, M., Anton, A., Soriano, T., Suarez-Rey, E.M., Castilla, N., 2011. Environmental impact of
screenhouse and open-field cultivation using a life cycle analysisi. The case study of green bean production.
J Cleaner Prod. On-line, doi:10.1016/j.jclepro.
Martínez-Blanco, J., Muñoz, P., Antón, A., Rieradevall, R., 2011. Assessment of tomato Meditarrean production
in open-filed and standard multi-tunnel greenhouse, with compost or mineral fertilizers, from an
agricultural and environmental standpoint. J Cleaner Prod. 19, 985-997.
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