European Journal of Sustainable Agroecosystems

Background: Conservation tillage practices, including no-tillage (NT) and reduced tillage (RT), have been widely advocated as viable management strategies to mitigate atmospheric carbon dioxide (COâ‚‚) emissions by enhancing soil organic carbon (SOC) sequestration. However, the mechanisms governing the stabilization of sequestered carbon across diverse pedoclimatic zones remain incompletely understood and continue to be debated.

Objective: This critical review aims to comprehensively evaluate the physical, chemical, and biological mechanisms responsible for soil carbon stabilization under conservation tillage systems. It also seeks to identify methodological limitations, reconcile conflicting findings, and highlight key geographic and research gaps in the current literature.

Methods: A systematic evidence synthesis was conducted using studies published between 2015 and 2025 retrieved from the Scopus, Web of Science, and ScienceDirect databases. The review critically assessed interactions among soil aggregate dynamics, mineral-associated organic matter (MAOM), particulate organic matter (POM), and microbial metabolic efficiency. It also evaluated analytical methodologies used to investigate soil carbon stabilization.

Results: The analysis indicates that NT substantially enhances physical protection of SOC through macroaggregate occlusion in topsoil (0–15 cm). However, it often results in depth-stratification, with reduced carbon storage in subsoil layers (>30 cm) compared with conventional tillage (CT). The review identifies important methodological shortcomings of conventional wet-sieving techniques and emphasizes the advantages of advanced non-destructive imaging technologies, including X-ray computed tomography and synchrotron-based spectroscopy. Additionally, conflicting evidence regarding MAOM saturation capacity and shifts in fungal-to-bacterial ratios was critically examined. Geographic assessment revealed a strong research bias toward temperate alfisols, with tropical oxisols remaining significantly underrepresented.

Conclusion: Although conservation tillage improves SOC stabilization in surface soils, its long-term effectiveness is constrained by subsoil carbon dynamics, methodological inconsistencies, and regional research imbalances. Future research should integrate molecular-scale biogeochemical analyses with ecosystem-scale modeling and employ advanced imaging technologies to improve understanding of SOC stabilization and strengthen climate change mitigation strategies.