Objective  The effect of rice straw addition on soil CH₄ emission in Black soil with different rice planting years in Northeast China needed to be evaluated, which will provide to provide a theoretical basis for the return of rice straw in paddy field of Black soil.

  Method  Flooding incubation experiment in a laboratory for 150 days (at 20 ℃, with 1 cm water-flooded layer) was carried out, and 1% rice straw was added to black soils with different rice planting years (0, 12, 35, 62 and 85 years), and the soil without rice straw addition was used as the control. The CH₄ emission flux and cumulative emissions from soil were determined.

  Result  During flooding incubation period (150 days), the soil CH₄ emission flux (0.00 - 3.33 mg kg⁻¹ d⁻¹) from the treatments with rice straw was significantly higher than that from the treatments without rice straw (0.00 - 0.13 mg kg⁻¹ d⁻¹). The CH₄ emission from the treatments without and with rice straw mainly occurred in the first 80 days and the first 60 days, respectively. The cumulative emissions of soil CH₄ from the treatments without rice straw were 0.04 - 4.45 mg kg⁻¹, there was no significant difference in soil CH₄ cumulative emissions in different rice planting years (P > 0.05). The cumulative emissions of soil CH₄ from the treatments with rice straw were 29.64 - 91.08 mg kg⁻¹, which was significantly higher than that of without rice straw treatments (P < 0.05), and the cumulative emissions of soil CH₄ from 12 years and 35 years were significantly higher than that of 0 year, 62 years and 85 years (P < 0.05). The cumulative emissions of CH₄ from the treatments without and with rice straw positive correlated significant (P < 0.01) with soil organic carbon (SOC), dissolve organic carbon (DOC), dissolve organic nitrogen（DON）and NH₄ ⁺ −N. The cumulative emissions of CH₄ from the treatments with rice straw negatively correlated significantly (P < 0.05) with β- Glucosidase activity, the cumulative emission increment of CH₄ positive correlated significant (P < 0.01) with SOC and DON in the treatments with rice straw addition, which means that the SOC and DON are the main affecting factors for CH₄ emission. While the DOC, NH₄ ⁺ −N and β -glucosidase activities were the indirect factors affecting soil CH₄ emission.

  Conclusion  These results suggest that the addition of rice straw significantly promots the CH₄ emission in Black Soil with different rice planting years, the longer the years of rice planting, the soil CH₄ emission is relatively lower. Therefore, the soil CH₄ emission increases from the treatments with rice straw addition is relatively small in more than 35-year rice planting Black soils