Travail de fin d'études en gestion des forêts et des espaces naturels : Per tonne or per hectare? How functional-unit choice reverses the sustainability performances of peri-urban agroecological and conventional vegetable farms : an environmental and economic analysis in Abomey-Calavi, Benin.

Abstract

Peri-urban market gardening plays a critical role in food supply across West African cities, yet the environmental and economic performance of agroecological farming systems remains poorly documented. This study assessed three market garden farms in Abomey-Calavi, Benin ; two agroecological (Les Jardins de l'Espoir and Ferme Agro-Eco) and one conventional (Agri MAP) ; using Life Cycle Assessment (LCA) and Life Cycle Costing (LCC) with two functional units: one hectare and one tonne of marketable production. Per hectare, Agri MAP showed the highest environmental impact in 9 of 18 categories, driven by grid electricity. Per tonne, Les Jardins de l'Espoir exhibited the highest values across all categories, reflecting its lower marketable yield (20 t/ha, vs. 146 t/ha for Agro-Eco and 116 t/ha for Agri MAP). Field emissions from organic amendments constituted the dominant hotspot, accounting for 28–79% of impacts depending on the farm. Economically, Les Jardins de l'Espoir achieved the highest annual cash flow (14,125,060 FCFA) through diversification across seven products. Agro-Eco maintained a positive cash flow (318,693 FCFA) despite concentrating 75.5% of revenues on a single crop. Agri MAP operated at a loss (−376,506 FCFA) due to high labour costs. Farm-level performance depends strongly on the metric considered. These findings provide a quantitative benchmark for smallholder agroecological market gardening in Benin, and underscore the importance of combining multiple functional units when evaluating agroecological transitions.