Trade-off analysis between soil organic carbon and maize yield under no-tillage: implication for sustainable cropland management.

Long-term intensive tillage has reduced soil organic carbon (SOC) and threatened sustainable maize production in Northeast China. Yet how tillage regulates SOC-yield relationship across climatic gradients remains unclear, limiting climate-smart cropland management. Here, we combined field observations with the DSSAT model to simulate long-term effects of conventional tillage (CT) and no-tillage (NT) on SOC and maize yield (MY) across the maize belt of Jilin Province, and qualified SOC-MY synergy/trade-off along aridity gradients. NT consistently increased SOC region-wide and improve MY on average, but yield benefits showed clear climatic thresholds. Yield gains were concentrated in moderately dry environments with intermediate water-heat availability (aridity index, AI ≈ 0.28-0.40). In humid zones (AI > 0.67), NT still promoted SOC accumulation but often failed to sustain MY, indicating a shift from co-benefit to trade-off. The area exhibiting simultaneous SOC and MY increases expanded rapidly during early adoption, stabilized in years 5-20, and gradually decline thereafter. These results demonstrate that NT co-benefit depend jointly on climate suitability and adoption stage, providing transferable thresholds for climate-informed promotion of conservation agriculture in temperate maize system.