Agriculture is a cornerstone of societal production, playing a pivotal role in food security, economic development, and environmental sustainability. However, the escalating use of chemical inputs and fossil fuels in agricultural systems has raised significant concerns about their environmental sustainability. This study employs the Life Cycle Assessment (LCA) methodology, in accordance with ISO 14044 standards, to evaluate the environmental impacts of four major crops—wheat, barley, alfalfa, and rice—in the Lenjanat watershed of Isfahan Province, Iran. The functional unit was defined as the production of one ton of each crop, with the system boundary encompassing all farm activities from land preparation to harvest. Data were collected for the agricultural year 2020–2021 and analyzed using SimaPro 9.2 software and the Ecoinvent database. The results indicated that rice had the highest Global Warming Potential (GWP) at 4137.85 kg CO₂-eq, primarily due to its high water demand and diesel fuel consumption. Wheat exhibited the highest Acidification Potential (AP) at 28.11 kg SO₂-eq and the highest Eutrophication Potential (EP) at 11.79 kg PO₄³⁻-eq, driven by excessive nitrogen and phosphate fertilizer use. Alfalfa, while showing the lowest GWP and EP, had the highest Photochemical Oxidant Formation Potential (POFP) at 0.392 kg C₂H₄-eq due to frequent harvesting operations. The study underscores the critical role of nitrogen fertilizers, diesel fuel, and phosphate fertilizers in environmental impacts. To mitigate these effects, adopting organic inputs, modern irrigation technologies, reduced tillage, and optimized fuel use are recommended. These strategies can significantly enhance agricultural sustainability in the Lenjanat region.
