Defence of a thesis by Aurélie Perrin

This thesis project, implemented in the Hortsys Unit under the supervision of Claudine Basset-Mens (tutor) and Benoît Gabrielle (PhD supervisor), dealt with a new line of research for CIRAD: the environmental assessment of tropical products using the life cycle assessment methodology.
The first environmental assessment of urban farming systems in Africa using the Life Cycle Assessment methodology was undertaken. All the inputs (fertilizers, pesticides, water, equipment) used for tomato production in Benin were first quantified, along with the release of pollutants into the environment. Nitrogen emissions arising from the application of fertilizers were modelled, such as nitrates which contribute to the eutrophication of coastal waters, ammonia which contributes to acid rain, and N2O which contributes to global warming. This study showed that the environmental impact of Beninese tomato cultivation is greater than that of European market garden crops due to the poor performance of irrigation equipment, excessive insecticide use and high nitrogen emissions. The results of this thesis suggest that reducing the environmental impacts of African market gardening systems in an urban context calls for farmers to be trained in the risks associated with the use of phytosanitary products and for fertilization practices to be optimized by taking into account soil and climate conditions.

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