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Pré-Publication, Document De Travail (Preprint/Prepublication) Année : 2022

Effect of farm type and functional unit on environmental impacts of organic vegetable farms

Résumé

This text is a pre-print of a paper submitted to the Journal of Cleaner Production (currently under review). French organic vegetable farms are diverse, ranging from complex biodiversity-based systems with many vegetables to simple input-based systems with few vegetables, which suggests that their impacts on the environment may differ. We used life cycle assessment (LCA) to assess impacts of three contrasting farms: a microfarm (MF, high crop diversity and a low input level), a medium-sized farm specialised in sheltered production (SP, low crop diversity and a high input level), and a large farm specialised in open-field production (OP, intermediate input level and crop diversity). To manage the complexity of organic vegetable farms, we opted for a system LCA, based on farm inputs and output (i.e. « vegetables ») for a one-year period. Using functional units based on mass of output, area, and economic value, we analysed five impacts: climate change, cumulative energy demand, marine eutrophication, on-farm biodiversity, and the use of plastic. Farming-system LCA assessed environmental impacts of farms with different levels of agroecology, including complex systems with a large diversity of crops grown on small areas. The three functional units strongly influenced the ranking of the systems. Per ha, the systems differed greatly in climate change and energy demand: SP had the highest impacts, whereas OP had the lowest impacts. Per kg and per €, the systems differed much less in climate change and energy demand, and even ranked differently. OP used much less plastic but performed worse on biodiversity and yield. Despite its higher yield, SP performed no better than the other two farms for climate change, energy demand, and plastic use per kg and €. The impact on biodiversity contrasted with the other impacts, which highlighted the importance of semi-natural habitats. Quantification of plastic use echoed growing concerns about (micro-)plastic pollution in agricultural soils and landscapes, and the newly identified planetary boundary on novel entities. Estimating nitrate leaching was difficult, and the Intergovernmental Panel on Climate Change (IPCC) Tier 1 model used to do so seemed unsatisfactory; thus, estimated marine eutrophication impacts had high uncertainty. Crop residues contributed greatly to marine eutrophication. In this perspective, models for estimating crop residues and nitrate leaching in a farming-system LCA approach need to be improved. In agroecological systems, semi-natural habitats are part of the farming system. The farming-system LCA approach requires clear rules for setting farm boundaries, which strongly influence impacts per ha and biodiversity impacts.
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Dates et versions

hal-03765570 , version 1 (13-10-2022)

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  • HAL Id : hal-03765570 , version 1

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Antonin Pepin, Marie Trydeman Knudsen, Kevin Morel, Hayo van Der Werf, Philippe Jeanneret. Effect of farm type and functional unit on environmental impacts of organic vegetable farms. 2022. ⟨hal-03765570⟩
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