有机肥替代不同比例化肥对土壤有机碳组分的影响

东北黑土是我国宝贵的耕地资源，是重要的商品粮基地。为了明确东北春麦区有机肥替代化肥的最佳用量，提升土壤质量，在田间开展了有机肥替代部分化学氮肥研究，试验共设不施肥（CK）、有机肥替代100%化学氮肥(M)、有机肥替代50%化学氮肥(M₁N₁)、有机肥替代25%化学氮肥(M₂N₂ )和全化学氮肥处理(N)5个处理，分析了不同化肥处理对小麦收获期耕层土壤（0～20 cm）有机碳组分的影响。结果表明，土壤总有机碳含量以M处理最高，为24.30 g·kg^-1；N处理下土壤全氮含量显著高于其他处理，为2.70  g·kg^-1；施用有机肥能够增加土壤C/N比例。有机无机配施能显著增加土壤活性有机碳组分含量，土壤ROC和MBC含量均以M₂N₂处理含量最高，分别为4.69 g·kg^-1及317.40 mg·kg^-1；土壤DOC含量以M处理最高，为325.97 mg·kg^-1，M₂N₂处理次之，为307.83 mg·kg^-1；土壤POC含量以M₁N₁处理最高，为1.38 g·kg^-1。分析土壤有机碳组分对施肥的敏感性指数得出，各活性碳SI值均高于SOC，以M₂N₂处理下MBC的敏感性最高。经相关性分析，ROC、MBC、POC之间存在极显著相关关系（P<0.01）。在东北春小麦种植区域，采用有机肥替代25%～50%化肥能够增加土壤有机碳组分含量，提高C/N。MBC对施肥反应最为敏感，可作为指示该地区土壤有机物早期变化的指示物。

Effect of Different Proportions of Labile Organic Fertilizer Substituted by Nitrogen Fertilizer on Components of Soil Organic Carbon

The black soil in Northeastern China is a valuable cultivated land resource and an important commodity grain base in China. To determine the best amount of organic fertilizer instead of chemical fertilizer in the spring wheat planting area and to improve soil quality, the field experiment was conducted to study the technology of organic fertilizer instead of chemical nitrogen fertilizer. There were five treatments in this experiment: no fertilizer(CK), organic fertilizer replacing 100% chemical nitrogen fertilizer(M), organic fertilizer replacing 50% chemical nitrogen fertilizer(M₁N₁), organic fertilizer replacing 25% chemical nitrogen fertilizer(M₂N₂) and 100% chemical nitrogen fertilizer(N)to study the effects of different chemical fertilizer treatments on the organic carbon components of 0-20 cm soil layer during wheat harvest. The results showed that the total organic carbon content under M treatment was the highest, which was 24.30 g·kg^-1. The total nitrogen content of soil under N treatment was 2.70 g·kg^-1, which was significantly higher than that of other treatments. Application of organic fertilizer can increase the C/N ratio in soil. The results showed that the combined application of organic and chemical fertilizer significantly increased the content of soil active organic carbon, and the content of soil ROC and MBC under M₂N₂ treatment were the highest, which were 4.69 g·kg^-1 and 317.40 mg·kg^-1, respectively. Soil DOC content under M treatment was the highest, 325.97 mg·kg^-1, followed by that under M₂N₂ treatment, 307.83 mg·kg^-1. The content of POC under M₁N₁ was the highest, which was 1.38 g·kg^-1. According to the analysis of the sensitivity index(SI) of soil organic carbon components to fertilization, the SI value of each active carbon was higher than that of SOC, and the sensitivity of MBC was the highest under M₂N₂ treatment. ROC, MBC and POC were significantly correlated with each other(P<0.01). In the northeast spring wheat planting area, using organic fertilizer instead of chemical fertilizer at a proportion of 25%-50% can increase the content of soil organic carbon and C/N ratio. MBC is the most sensitive index to fertilization and can be used as an indicator of the early changes of organic matter in this area.