Life cycle assessment of Mediterranean hay production under variable climatic conditions: a case study

Hay production represents a strategic component of Mediterranean forage systems, particularly in regions increasingly exposed to climatic variability. Despite its relevance for livestock-based economies, dedicated life cycle assessment (LCA) studies on hay production in semi-arid environments remain limited, and the influence of interannual climatic fluctuations on environmental performance is poorly documented. For this reason, the aim of the study was to apply LCA methodology to evaluate the environmental impacts associated with the production of mixed hay cultivated on a farm located in Cammarata (Agrigento, Italy) across three contrasting seasons (2021–2022, 2023–2024 and 2024–2025). These periods were characterized by substantial differences in rainfall distribution and yield. Two functional units (1 ton of hay; and 1 ha of cultivated land) and two life cycle impact assessment methods (CML-IA baseline and ReCiPe 2016 Midpoint/Endpoint) were adopted to improve robustness and comparability of results across different characterization models. Primary data were collected through field surveys, while secondary data were sourced from Ecoinvent database. Weighting and sensitivity analyses were used to support result interpretation. Results indicated that the driest season (S2) exhibited the lowest impacts per hectare but the highest impacts per ton of productivity. Under a mass-based functional unit, S2 recorded global warming potential values up to four times higher than the other seasons (S1 and S3), while under a land-based functional unit it consistently emerged as the lowest environmental impacts and the most favorable area-based profile. Across both the CML and ReCiPe methods, fuel consumption dominated impacts such as abiotic depletion, fossil depletion, and global warming potential, whereas fertilizers and on-field emissions were the main contributors to acidification, eutrophication, and marine ecotoxicity. Endpoint analysis indicated human health as the most impacted area of protection. Overall, the study demonstrates that climatic constraints strongly modulate environmental burdens in hay production. These findings highlight the importance of integrating climate variability into life cycle assessment and the need for integrated strategies that enhance mechanization efficiency, improve nutrient management, and adopt innovative technologies to increase resilience under increasing climatic stress.