1 Grain legumes and the environment. How to assess benefits and impacts. European Association for Grain Legumes Research AEP, Paris, 2006, 41-44.
Methodology for environmental assessment of grain legumes: state of the art
G. GAILLARD, Agroscope Reckenholz-Tänikon ART, CP 412. 8046 Zürich R. CHARLES, Agroscope Changins-Wädenswil ACW, CP 1012, 1260 Nyon 1
H. VAN DER WERF, INRA, UMR Sol, Agronomie et Spatialisation de Rennes-Quimper, AGROCAMPUS, 65 rue de Saint-Brieuc CS 84215, 35042 Rennes Cedex, France
E-mail : gerard.gaillard@art.admin.ch
Choice of a methodological framework
In the invitation to submit a presentation to the GL-Pro workshop the choice of methodology to be used for assessing the environmental impacts of grain legume production and consumption was deliberately Ieft open. One of the major questions was to find out whether the LCA (Life Cycle Assessment) methodology selected for the GL-Pro project is supported by the scientific community. The majority of the contributions dealt with the LCA method, both from a theoretical point of view (discussion of the limits of the system, the functional unit or the allocation procedures: see 4; 6) and in the form of case studies (beans, peas, feeding strategies: see 2; 6). Several aspects of the nitrogen cycle, especially relevant when assessing grain legumes, were also analysed using the LCA methodology (rote of N fertilisation, impact on greenhouse gas emissions: see 3; 1).
The successful application of LCA by different research teams can be considered as proof of the applicability of this methodology for grain legumes. However, the points raised by these authors on the one hand, and the constructive but also critical questions from the workshop participants on the other hand, underline the need for further investigations and research to establish the LCA methodology firmly-in this context. Several of these issues will be addressed in this paper.
However, at the workshop, LCA was not the only framework considered for assessing the impacts of grain legume production and consumption on the environment. Helms (5) proposed an alternative approach based on the ambivalent behaviour of mankind in relation to land use. On the one hand, as mankind needs land to live, the assessment includes the three functions biomass production', `energy production' and
`water supply', which enable the production of proteins. On the other hand, mankind damages the environment, which leads Helms (5) to assess the three so-called remedial functions `biodiversity conservation', `nitrogen retention' and `phosphorus retention'. There was not the opportunity to discuss fully this methodology during the workshop and there was some scepticism about the quantifying procedures, but this often occurs with new ideas. With this exception, the entire methodological discussion dealt with LCA.
Goal and scope: which nutritional functions are fulfilled?
Most members of the scientific community dealing with grain legume production and use in the context of European agricultural production consider their use as animal feed, and this is the context for the GL-Pro project. Van der Werf (6) discussed the rote of a precise definition of the nutritional functions being fulfilled by grain legumes:
For protein-rich feed ingredients, he recommended crude protein as a functional unit, but a second function, supplying energy in addition to protein, should not be omitted. Cederberg (2) progressed from an LCA of grain legume production to an LCA of grain legume use, and this led her to consider bone-free pig meat as the functional unit.
However, several speakers considered the fact that grain legumes can also be used directly for human nutrition. This not only increases the scope of the crops under study (for example soya beans gain in importance), but also the question of the environmental advantage of protein consumption based on grain legumes takes a quite different dimension. The central argument for the environmental benefits of grain legume production is no longer the improved nitrogen cycle, but rather the consumption of grain legumes directly by human beings instead of indirectly through pork or chicken meat. Then the major question is how to improve the human food cycle. Fogelberg (communication at the workshop) demonstrated the environmental advantages to be expected from eating peas and beans, whereas Helms (5) based her conclusions on a hypothetical novel protein food as a substitute for meat. Other researchers like van der Werf (6) or Cederberg (2) showed how to optimise the feeding system using grain legumes in pork production.
The challenge for the scientific community is to combine these two different points of view. Indeed, it can be assumed that a vegetarian food system should be more favourable from an LCA point of view, due to its higher inherent efficiency. Such results are known for nutritional energy, and are likely to be the same for proteins. But should LCA address this question when assessing grain legume production and use and consequently systematically favour vegetarian diets? Or should we assume that eating meat is such a fundamental right for mankind, that the environmental assessment of grain legume production and use should be restricted to the environmental optimisation of animal production systems, without considering
2 any vegetarian diet as an alternative? We feel that the overall assessment of grain legumes should address both aspects of protein consumption - vegetarian diet and meat. This work remains largely to be done.
Gaillard et al. (4) pointed out another dimension of the LCA of grain legume production and use. In addition to the nutritional function - whatever it may be - the whole assessment should also consider financial and land management functions due to the multifunctionality of agriculture. This consideration makes the whole assessment more complicated, but also more relevant for political and societal decision-makers. The discussion demonstrated the importance of the audience addressed by the LCA. One participant pointed out that there is little experience on how to reach a scientifically-sound consensus considering the objectives of farmers, feed compound producers and users.
Limits of the system: from the product LCA up to world scenarios
Performing an LCA is not a simple task and the different studies presented at the workshop deserve respect. But is it scientifically correct to limit the system analysed to a simple product system, as usually done in the LCA world? Practically ail the studies discussed at the workshop were established at the crop level, which is very useful for different sensitivity analyses as in Cederberg (2) or van der Werf (6). Gaillard et al. (4), however, insisted on the need to situate the study at the crop rotation level, and Charles (3) included the residual nitrogen effect of a grain legume on the following crop, which can be considered as a first step in this direction.
The discussion with workshop participants brought a wider dimension to the debate.
How can we assess the environmental impact of grain legumes in a completely liberalised world market? If Europe bans soya beans, will Brazil produce peas for us and how can this be taken into account? Is overseas transport a relevant item (6)? lnstead of calculating LCA for product systems or for a whole crop rotation, should we begin with complex scenarios covering the world production of selected diets for animal and human nutrition? And if yes, with which hypotheses? Here research finds itself facing a big challenge.
Accuracy and completeness
In view of all these difficulties, the accuracy of the results is in question. One participant observed that it is a pity that uncertainties are not assessed, as is often the case for other scientific disciplines. In the case of world scenarios, the regionalisation of the assessment is a major question. Objectively, we should not assess the environmental impact of grain legumes in South America and in Europe with the same parameters - but this is being done. The extrapolation of LCA methodology validated for a precise context to quite different situations is one of the major challenges for environmental assessment research.
Last but not Ieast, the different studies presented were unable to cover all environmental aspects linked with the production and use of grain legumes. This limitation is well known and not specific to grain legumes, nevertheless it is also a research challenge for the future.
Conclusions
The session `Methodology for environmental assessment of grain legumes: state of the art' demonstrated that, in most cases, we can assess the environmental impact of grain legume production and use, on an LCA basis. However, it was recognised by all those involved, the speakers as well as the workshop participants, that a large number of major and minor challenges is still to be met before a methodology that can be recommended without restriction is achieved.
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