A multi-criteria evaluation of the environmental performances of conventional, organic and integrated olive-growing systems in the south of Spain based on experts' knowledge

Abstract

The medium to long-term environmental performances of organic, integrated and conventional olive-growing systems in the average conditions of the south of Spain are evaluated and compared with respect to soil erosion, soil fertility, rational use of irrigation water, water contamination, atmospheric pollution and biodiversity, based on experts' knowledge. The aim of the research was to test the common implicit assumption of environmental superiority of the two alternative farming systems over the conventional system. For this purpose, the Analytic Hierarchy Process (AHP), a widely used multi-criteria decision-making tool, has been implemented. AHP enables us to deal with complex decision-making problems with multiple criteria, stakeholders and decision-makers, high uncertainty and risk, such as in the case of multi-criteria environmental comparison of alternative farming systems. Twenty experts in olive production, clustered into three groups according to their professional field of interest, were involved in the analysis. The utilization of experts' knowledge is justified when information relevant for urgent decision-making is not available, is partial or is time and resource demanding, and a holistic perspective is required. Indexes and procedures are proposed for group decision-making, to detect variation in expert opinions and differences between alternative systems' performances. Despite bias in the judgments of the groups of experts in some topics, results confirm the holistic environmental superiority of organic and integrated alternatives over the conventional olive system in Andalusia in the medium to long-term. The results represent a scientific base to justify and endorse institutional support regarding the promotion and implementation of organic and integrated olive-growing systems in the region, which are likely to result in greater social welfare.

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