Comparing energy balances, greenhouse gas balances and biodiversity impacts of contrasting farming systems with alternative land uses

Life cycle assessment (LCA) is commonly used for comparing environmental impacts of contrasting farming systems. However, the interpretation of agricultural LCA studies may be flawed when the alternative land use options are not properly taken into account. This study compared energy and greenhouse gas (GHG) balances and biodiversity impacts of different farming systems by using LCA accompanied by an assessment of alternative land uses. Farm area and food product output were set equal across all of the farm models, and any land remaining available after the food crop production requirement had been met was assumed to be used for other purposes. Three different management options for that land area were compared: Miscanthus energy crop production, managed forest and natural forest. The results illustrate the significance of taking into account the alternative land use options and suggest that integrated farming systems have potential to improve the energy and GHG balances and biodiversity compared to both organic and conventional systems. Sensitivity analysis shows that the models are most sensitive for crop and biogas yields and for the nitrous oxide emission factors. This paper provides an approach that can be further developed for identifying land management systems that optimize food production and environmental benefits.