|Abstract:||Industrialized agricultural production of annual row crops, such as corn and soybeans, is a major contributor to several environmental problems, including climate change and eutrophication of waterways. Land use transition to multifunctional woody polyculture (MWP) agroecosystems has been proposed as a potential strategy for mitigating these harmful impacts while still yielding high value crops. Life Cycle Assessment (LCA) has the potential to meaningfully capture these impacts, enabling improved decision making in agricultural management. However, due to the differences in the life cycles of various agroecosystems, LCA methodology must be evaluated across multiple agroecosystems to ensure best practices in evaluating these systems. This study evaluated the importance of various LCA methodological decisions - including system boundary and functional unit selection, collection of uncertain inventory data, and modelling of ecosystem services – across ten agroecosystems, corn-soy rotation, four monoculture orchards, and five multifunctional woody polycultures.
Environmental impacts across all agroecosystems were found to be dominated by emissions from the burning of fuel for agricultural machinery, and from the production and use of fertilizers and pesticides. The majority of these impacts are associated with the production phase of all crops’ life cycles, and suggestions are made for when all phases, including the nursery, transportation, establishment, production, and destruction of crops must be included in LCA. Results suggest that environmental impacts are more strongly related to management decisions, such as chemical application rate, than crop selection, but additional work is necessary to fully integrate the ecological variation of agroecosystems into a quantitative framework such as LCA.