S15 - Session O2 - Environmental assessment of contrasted French organic vegetable farms

Authors: Antonin Pépin *, Hayo van der Werf, Kevin Morel, Dominique Grasselly, Marie Knudsen

French organic vegetable farms are diverse, ranging from biodiversity-based farming systems, characterised by a high number of vegetables (about 40) in a complex system, most often on small areas, to simple input-based farming systems, characterised by a small number of vegetables (about 10), grown in greenhouse or in large open-fields. The different levels of input use and yield of these systems may lead to different environmental impacts. We analysed the impacts on climate change, marine eutrophication and biodiversity of three contrasted farms, using Life Cycle Assessment (LCA) methodology at farm scale. We assessed the impacts at farm gate, per kg of produced vegetable and per ha of cultivated land, considering the vegetable production as a "black box": we considered total annual vegetable production and total inputs consumed without specifying which input is used for which crop. The large open-field farm had the lowest climate change impact: 130 g CO 2 eq./kg of vegetable and 1.4 t CO 2 eq./ha with diesel and field N 2 O emissions as main contributors. The microfarm with both sheltered and open-field production had 180 g CO 2 eq./kg of vegetable and 7.8 t CO 2 eq./ha, the main contributors being the tunnel structure (steel and plastic) and compost production. The farm specialized in protected crops had 200 g CO 2 eq./kg of vegetable and 14 t CO 2 eq./ha, its main contributors were the tunnel structure, early seedlings produced in a heated greenhouse, and plastic mulch. We compared the three farms from an agronomic point of view (e.g. weed control with plastic mulch or by harrowing) and identified options to reduce their environmental impacts. We discussed potential methodological improvements (e.g. methods to estimate carbon and nitrogen soil sequestration, environmental burden of livestock manure versus compost, biodiversity assessment methods, limits of the "black box" approach) and suggested ways to better assess complex farms.