Sorting cropping systems on the basis of their impact on groundwater quality

In this paper is described the implementation of a multi-criteria analysis in order to answer a question of researchers of the Institut National de la Recherche Agronomique who assess the impact of agricultural practices on the environmental components. They were particularly interested in differentiating cropping systems (CSs) as a function of their impact on groundwater quality. In order to give effect to this differentiation, members of the Laboratoire d'Analyse et de Modélisation de Systèmes pour l'Aide à la Décision proposed a way of sorting CSs using the ELECTRE TRI method. Four categories of impact were defined and three families of criteria were built up. The main debate was about the nature of criteria: if basic data are used, the number of the criteria is high; if aggregated data are used, exchanges of information are tedious. In spite of difficulties, the study has been of important value for the agronomic researchers. Firstly, it helps them to work with decision-makers, such as the Water Agency: it allows farmers to be given concrete examples of CSs which preserve groundwater quality. Secondly, the multi-criteria methodology used seems to fit their researches: they are indeed now using the same approach to differentiate CSs on the basis of their impact on wild fauna or landscape quality.