Environmental impacts and potential mitigation options for organic open-field vegetable production in Denmark assessed through life cycle assessment

Abstract

A shift in food intake towards more plant-based options such as vegetables is emphasised for lowering the environmental impact of food consumption, and organic farming is promoted as a tool to meet European policy goals related to sustainability, environment and biodiversity. However, the current environmental impact of organic vegetable production is not well explored. Here we address the knowledge gap of environmental impacts from organic vegetable production in a life cycle perspective, locate primary impact sources and investigate potential mitigation option scenarios. The assessment focussed on pointed cabbage, cos lettuce and yellow onion in a mixed crop rotation, as common under commercial Danish conditions, and include estimation of soil carbon (C) and nitrogen (N) pools. The system boundary was set from cradle to farm gate, and included inputs to cultivation, soil C and N dynamics in the crop rotation, post-harvest cooling, packaging and storage. The data for modelling was collected from growers, consultants and the scientific literature. We report estimated global warming potential, marine eutrophication potential, land use, water consumption, mineral and fossil resource scarcity and cumulative energy demand from production. The analysis shows that environmental impacts stemmed from several activities dependent on the crop-specific characteristics of production. For summer-grown pointed cabbage, nitrous oxide emissions from high amounts of fertiliser and crop residue was responsible for 40 % of climate impacts, for cos lettuce the production of seedlings with peat as a substrate was responsible for 40 % of climate impact, and for transplanted yellow onion the post-harvest drying and storage was responsible for 27 % of climate impacts. The identified major mitigation options were an increase in harvest shares of hand-harvested vegetable crops, lower post-harvest loss from onion storage, optimised residue management and substitution of peat as substrate for seedling production. These are promising avenues for lower environmental impact.