Lessons learned from existing carbon removal methodologies for agricultural soils to drive European Union policies

Soil plays a central role in the global carbon (C) cycle and the fight against climate change as it contains the largest existing organic C stock on earth. Natural processes exacerbated by climate change and unsustainable agricultural soil management practices are contributing to the steady decrease in organic C stocks in farmland. Carbon farming practices, underpinned by various incentives, can be used to maintain and increase C stocks in agricultural soils. Carbon credit mechanisms, that is, tradable credits each corresponding to one tonne of CO₂eq, are one such incentive. Carbon credits are issued upon the demonstration of increased soil C stocks over time through the application of C accounting methodologies for each agroecosystem and farming practice. This study presents a detailed and critical analysis of carbon credit methodologies, focusing on agricultural soil C in temperate zones, by comparing the European Commission proposal for a regulation on carbon removals with relevant certification frameworks implemented in extra-European Union industrialized countries (Australia, Alberta in Canada, United States). Based on this, we recommend strengthening the European Commission proposal by (i) expanding the list of eligible agricultural practices, (ii) setting a minimum maintenance time frame for each agricultural practice and incentivizing longer duration, (iii) setting the Good Agricultural and Environmental Conditions of the European Common Agricultural Policy (CAP) as a regulatory baseline, (iv) beyond the regulatory baseline, defining a farm level baseline in terms of carbon farming practices applied that can be monitored through the Integrated Administration and Control System of the CAP, (v) clarifying the interaction between the European Commission proposal of regulation and the CAP, the Soil Monitoring Law, and Land Use/Cover Area Frame Survey inventory, (vi) retaining a portion of unsold carbon credits as a buffer against the risk of reversal and (vii) applying a default discount to account for leakage risk if yield reductions are observed. We propose these recommendations to guarantee effective environmental protection, technical and bureaucratic feasibility as well as economic affordability for farmers.