Life Cycle Assessment (LCA) is usually carried out using fixed coefficients for resource use and emissions as the basis for the calculation of the environmental impact of a product or a service. However, in agriculture, where the systems' functioning largely depends on the dynamic organisation of agricultural practices and on variable climatic conditions, coupling dynamic simulation models with LCA seems necessary. This paper presents the combination of a dynamic simulation model and LCA to assess the environmental impact of a collective pig slurry management system. The model simulates the production of slurry, its stock level in storage facilities, its transport and application to crop fields, as well as the gaseous emissions occurring in these stages, under different management strategies and climatic conditions. Results from the combination of these approaches show the great variability of the agronomic and environmental performance of the collective slurry management system in relation to different organisational schemes, agronomic decisions and climatic conditions.