Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Oat is mainly produced in northern latitude countries such as Canada, which is world's second largest producer. Hence it is necessary to study the environmental impacts of alternative farming systems to conventional oat production in order to improve its environmental performance. A life cycle assessment (LCA) was conducted to compare the environmental impacts and potential improvement opportunities of conventional and organic oat grain production using three different functional units (FU); per mass (t−1 of grains), surface area (ha−1) and gross sales income (1000 CAD−1). Most data were collected from a major farm located in Quebec, Canada. Our analysis shows that organic production is globally preferable based on the area and monetary FUs, whereas conventional production has lower impacts for 11 midpoint impact categories per ton of grain produced. In addition, organic production has higher damages on human health and ecosystem quality, both per ton of grain and per hectare. The relevance of each FU is discussed in the article. The hotspots of conventional oat production are the production and use of synthetic fertilizers, while those of organic oat production are the use of organic fertilizers and manure transportation. A sensitivity analysis showed that the choice of the N2O emission factor and phosphorus emission model considerably affects the magnitude of the impacts on climate change and freshwater eutrophication. Also, the implementation of green manure in the rotation system and the reduction of manure transport distances would significantly affect the results. In conclusion, our LCA case study does not support the idea that converting conventional oat grain production to organic agriculture would systematically decrease environmental impacts in eastern Canada. The environmental benefits largely depend on specific farmer practices and regional context.