From soil carbon towards system sustainability: Integrating SOC modelling and life cycle assessment to evaluate environmental trade-offs in carbon farming

The European Union (EU) is committed to reducing greenhouse gas (GHG) emissions to the atmosphere and promoting sustainable soil and land management practices. Carbon Farming (CF) is a set of practices to mitigate climate change in agriculture through carbon sequestration in soils. While CF practices increase soil organic carbon (SOC) stocks, they are also expected to have environmental impacts and potential trade-offs. However, the environmental impact of CF practices is often overlooked, and a comprehensive evaluation using Life Cycle Assessment (LCA) methodology is required. The RothC model was used to simulate SOC dynamics under different CF practices on arable land in Northern Italy: reduced tillage (RT), farmyard manure (FYM) application, and cover crops (CC). LCA methodology was applied to quantify GHG emissions and other environmental impacts beyond carbon. The results confirmed that different soil management strategies can significantly affect SOC accumulation. FYM application sequesters the most carbon (4.89 t C ha −1 over 20 years) due to exogenous carbon inputs. RT (1.34 t C ha −1 ) and CC (1.73 t C ha −1 ) also contribute to sequestration, but at lower rates. However, LCA results revealed significant trade-offs: while FYM maximizes carbon sequestration (0.90 t CO 2 ha −1 yr −1 ), it substantially increases acidification (+254 %), marine eutrophication (+372 %), terrestrial eutrophication (+243 %), and photochemical ozone formation (+290 %) compared to conventional agriculture. In contrast, CC and RT provide a balanced profile with moderate sequestration benefits (0.32 and 0.25 t CO 2 ha −1 yr −1 , respectively) and reduced environmental impacts, with RT showing improvements across all acidification and eutrophication indicators. This research underlines the critical need for comprehensive system assessment of agricultural sustainability, as CF may place too much emphasis on carbon sequestration without fully considering other environmental impacts requiring mitigation. • Exogenous carbon inputs result in the highest soil carbon sequestration. • Direct fertilizer emissions are the dominant source of greenhouse gas emissions. • Carbon sequestration does not fully offset greenhouse gas emissions. • Beyond carbon, the impacts of eutrophication and acidification are more relevant.