Abstract: 【Objective】To clarify the effects of straw-mulched strip tillage on soil organic carbon and its fractions in maize fields in the black soil region along the foothills of Daxing′anling Mountains,and to provide a basis for soil quality improvement and sustainable utilization in this region.【Methods】The experiment was carried out in Jalaid Banner of Hinggan League and Arun Banner of Hulun Buir City in Inner Mongolia from 2023 to 2024. Five tillage methods were established： conventional ridge tillage（CP）,no-tillage with straw removal（NT）,no-tillage with straw mulching（RNT）,straw-mulched strip tillage after autumn harvest（RST_A）,and straw-mulched strip tillage before spring sowing（RST_S）. The soil organic carbon and its fraction contents in 0-5,5-20 and 20-40 cm soil layers before sowing and after harvest were measured respectively. Organic carbon storage and soil carbon pool management index were calculated,and the effects on maize yield and its components were analyzed.【Results】Under the RST_S tillage method,compared with CP,in 0-5 cm and 5-20 cm soil layers after harvest in 2023 in Jalaid Banner and Arun Banner,the soil organic carbon contents significantly increased by 10.89%,10.07% and 6.09%,3.66%,respectively（P<0.05）,the particulate organic carbon contents significantly increased by 39.78%,28.49% and 37.56%,28.49%,respectively（P<0.05）,the light-fraction organic carbon contents significantly increased by 29.12%,33.82% and 21.87%,28.43%,respectively（P<0.05）,and the easily oxidized organic carbon contents significantly increased by 42.51%,45.19% and 38.46%,31.60%,respectively（P<0.05）;in 0-5,5-20,20-40 cm soil layers before sowing and after harvest in 2024,the soil organic carbon contents increased by an average of 12.50%,10.67%,7.84% and 7.56%,5.73%,6.21%,respectively,the particulate organic carbon contents increased by an average of 41.10%,28.79%,19.99% and 43.88%,38.19%,17.80%,respectively,the light-fraction organic carbon contents increased by an average of 57.00%,77.45%,36.07% and 25.65%,25.81%,5.92%,respectively,and the easily oxidized organic carbon contents increased by an average of 44.46%,44.19%,30.21% and 40.53%,37.30%,25.05%,respectively. Over the two years,in 0-5,5-20 and 20-40 cm soil layers in Jalaid Banner and Arun Banner,compared with CP,the soil organic carbon storage increased by an average of 8.01%,5.56%,1.78% and 7.15%,1.43%,1.62%,respectively;compared with CP,the carbon pool management index in the two experimental areas increased by an average of 100.02% and 99.62%,respectively. Over the two years,the maize grain yield under the RST_S tillage method in Jalaid Banner and Arun Banner were significantly higher than those under other tillage methods（P<0.05）,with average increases of 8.56% and 13.17%,respectively,compared with CP.【Conclusion】Straw-mulched strip tillage before spring sowing promotes the accumulation of soil organic carbon and its fractions,and significantly increases maize grain yield,achieving both soil fertility improvement and yield increase effects. It is a relatively suitable tillage method for soil carbon sequestration and fertilization in maize fields in the black soil region along the foothills of Daxing′anling Mountains.

Key words: Black soil region, Straw-mulched strip tillage, Soil organic carbon and its fractions, Carbon pool management index, Maize, Yield