Life cycle and economic assessment of corn production practices in the western US Corn Belt

Environmental impacts of corn production practices have been studied using life cycle assessment (LCA) across different regions across the world. Yet, most LCA on corn production focused on process-based approach, without considering environmental impacts embedded in economic service activities (e.g., insurance and overhead management). Besides, joint assessment on environmental and economic impacts of various corn production practices as well as trade-offs analysis between different environmental impact categories for different corn production practices also remains rare. To fill these knowledge gaps, a hybrid inventory approach is applied to account for environmental impacts of corn production employing different practices in different regions of Nebraska (a representative state of western US Corn Belt). The environmental and economic impacts of corn production are found to vary with geographical regions, water sources, and corn seed hybrids. Trade-offs between global warming potential (GWP) and overall environmental burdens (represented as a composite single score) are found among practices; that is, practices with lower GWP do not necessarily have a lower overall environmental single score (a composite of ten environmental impact categories). Improving the energy efficiency of existing diesel irrigation pumps offers an important avenue to reduce GHGs and environmental impacts from irrigated corn practices. Environmental impacts from economic service activities only have a marginal contribution to the overall results; among all practices, the largest contributions are on fossil fuel depletion (1.6 to 6.6%), implying that a process-based inventory is sufficient. The production costs and crop yield among the seven practices range from $145.6 to $218.0 per ton and 2286 to 6858 kg per acre. The analysis of crop yield variability shows that the irrigated practices help reduce variability of GWP, environmental single score, and production cost, compared to the rainfed practices. The methodology framework applying hybrid LCA and joint environmental and economic assessment at detailed process level can also be used to quantify the environmental impacts of other crops and be extended to develop fast and flexible assessment tool towards sustainable agricultural production.