Soil Carbon Persistence in a Changing Climate: A Critical Appraisal of Molecular Stabilisation Mechanisms and Their Translation into Climate-Smart Land Management
Amit Phonglosa *
Directorate of Extension Education, Odisha University of Agriculture and Technology, Bhubaneswar-751003, Odisha, India.
*Author to whom correspondence should be addressed.
Abstract
Soil holds more organic carbon than the atmosphere and the vegetation combined, and the length of time that carbon remains there governs whether land management can contribute meaningfully to climate mitigation. Over the past fifteen years the explanation for that persistence has been rebuilt. Intrinsic molecular recalcitrance has given way to an ecosystem-level account in which mineral association, spatial inaccessibility, microbial physiology and environmental constraint jointly determine residence time. This review critically evaluates that reconstruction and asks how securely it supports the land-management prescriptions now being written into carbon markets and national mitigation strategies. Peer-reviewed literature published mainly between 2005 and 8 July 2026 was identified through open scholarly indexes and citation searching, appraised for methodological adequacy, and synthesised thematically around mechanism, climate response, model representation and management translation. The evidence for mineral association as the dominant control on decadal to centennial persistence is strong and multiply replicated, yet three influential extensions of that framework remain insecure. The proposition that mineral-associated organic matter has a texture-defined saturation limit is contradicted by inventory data showing no detectable upper bound; the proposition that microbial carbon use efficiency is the principal global determinant of carbon storage is contradicted by manipulative experiments in which efficiency exerted no clear effect on mineral-associated carbon formation; and the proposition that microbial necromass dominates stabilised organic matter is not general across biomes. Warming experiments demonstrate substantial loss from whole soil profiles, including subsoil, and particulate organic carbon emerges consistently as the vulnerable fraction. A recurrent finding that carbon-rich soils contain younger rather than older carbon undermines the assumption that accrual and persistence move together. The practical consequence is that management should be appraised against the fraction in which carbon accumulates and the conditions under which it is retained, rather than against bulk stock change alone.
Keywords: Soil organic matter, mineral-associated organic carbon, particulate organic carbon, carbon use efficiency, carbon saturation, soil carbon sequestration, climate feedback, land management