Improving soil carbon stabilization within conservation agriculture: An adaptive framework

CONTEXT Conservation agriculture (CA) is widely promoted for improving soil ecosystem services, including erosion reduction, water conservation, and soil health. Its contribution to soil organic carbon (SOC) restoration, however, is variable, often modest and concentrated near the surface and strongly dependent on climate, soil, residue management and cropping system. OBJECTIVE To examine why SOC stabilization under CA is limited in some systems and to propose an adaptive framework that increases the probability that crop-residue carbon (CR-C) and root-derived C are converted into more stable SOC pools. METHODS We synthesize evidence on CR-C fate, root-derived C, SOC fractions, nutrient stoichiometry and soil-profile placement, under CA and organize this evidence into a diagnosis-based adaptive framework that links intervention choice with evidence strength, operational feasibility and trade-offs. RESULTS AND CONCLUSIONS A central limitation is the low but highly variable conversion of aboveground CR-C into stabilized SOC, governed by soil texture, mineralogy, climate, residue quality, nutrient availability, rooting depth and time since CA adoption. We propose an adaptive CA framework with six optional, evidence-graded interventions triggered by diagnosed SOC-stabilization bottlenecks: (1) residue retention thresholds to avoid a “problem of plenty”; (2) conditional strategic soil disturbance for compaction, surface stratification and C placement; (3) companion crops that improve residue amount, quality and root inputs; (4) breeding and selection for root traits for deeper C delivery and SOC stabilization; (5) fertilization strategies that better align decomposition with microbial stoichiometric needs while considering trade-offs; and (6) fungal consortia to accelerate lignocellulose breakdown where field conditions support residue turnover without increasing C losses. Together these interventions provide an adaptive extension of CA that can improve the likelihood of measurable and more durable SOC stabilization where specific bottlenecks are diagnosed. SIGNIFICANCE Options exist to strengthen the SOC-stabilization component of CA where site-specific bottlenecks are present, while explicitly considering feasibility, costs, trade-offs and the need for empirical validation through long-term monitoring of whole-profile SOC stocks and greenhouse-gas outcomes.