不同施肥处理黑土中添加秸秆对土壤团聚体稳定性及有机碳贡献率的影响

Effects of Straw Addition on Stability of Soil Aggregates and Contribution of Organic Carbon Under Different Fertilization Treatments in Black Soil

    摘要
  • 摘要:
      目的  探讨黑土中添加秸秆对团聚体稳定性及有机碳贡献率的影响，为东北黑土地保护提供依据。
      方法  基于43年的黑土长期定位试验，选取不施肥（CK）、单施有机肥（M）、单施氮磷钾化肥（NPK）、常量有机肥配施氮磷钾化肥（MNPK）和高量有机肥配施化肥（M2N2P2）5种处理的土壤，添加等量秸秆（相当于实际生产的全量秸秆还田）后采用砂滤管法进行田间原位培养，在培养的第0、60和150 d取样分析土壤团聚体的稳定性、团聚体有机碳含量及添加秸秆对土壤有机碳的贡献率。
      结果  添加秸秆促进了土壤大团聚体（> 250 μm）的形成，提高了大团聚体的比例，其中，常量有机肥配施氮、磷、钾化肥处理大团聚体含量增加效果显著，高于其它施肥处理；但随着培养时间的增加大团聚体含量减少，随之团聚体的稳定性呈现下降趋势。添加秸秆能够提高土壤大团聚体有机碳的含量，且高量有机肥配施化肥处理增加效果较好。单施有机肥、单施氮磷钾化肥、常量有机肥配施氮磷钾化肥处理中添加的秸秆对大团聚体有机碳的贡献率均达到80%以上（P < 0.05）；但随着培养时间的增加，秸秆对大团聚体有机碳贡献逐渐下降，而对53 ~ 250 μm和 < 53 μm团聚体有机碳贡献率呈上升趋势，有机碳在较小粒级的土壤团聚体中积累，进一步说明添加秸秆会影响团聚体分布的比例，进而影响团聚体有机碳的贡献率。
      结论  添加秸秆提高了黑土团聚体稳定性和有机碳含量，高肥力（M2N2P2）黑土配合秸秆还田可以提高土壤有机碳的固存能力。

     

    Abstract:
      Objective  To explore the effect of straw application on stability of soil aggregates and their contribution to organic carbon (C) sequestration can provide a basis for the protection of black soil in northeast China.
      Method  Based on a long-term (43 years) experiment of black soil, five treatments, no fertilization (CK), single application of organic fertilizer (M), single application of nitrogen, phosphorus and potassium fertilizer (NPK), organic fertilizer combined with nitrogen, phosphorus and potassium fertilizer (MNPK) and high amount organic fertilizer combined with chemical fertilizer (M2N2P2) were selected. The same amount of straw (equivalent to the amount of full straw returning in the actual production) was added into silicon tube and was incubated in the field. The soil aggregate stability, organic C contents of soil aggregates and their contribution rate to soil organic C sequestration were analyzed by sampling on the 0, 60th and 150th days of incubation.
      Result  The application of straw promoted the formation of > 250 μm macro-aggregate and increased the proportion of macroaggregates. The contents of macroaggregates increased significantly in the treatment of MNPK, which was higher than that in other fertilization treatments. However, the contents of large aggregates decreased with the increase of incubation time, and the stability of aggregates decreased. The straw addition increased the contents of organic C in > 250 μm aggregate, especially in the treatment of M2N2P2. The contribution rates of the added straw to soil organic C of > 250 μm aggregate were more than 80% (P < 0.05) in the treatments of M, NPK and MNPK. The contribution rates of added straw to soil organic C of >250 μm aggregates was decreased gradually with incubation time. However, this contribution rates to 53-250 μm and < 53 μm aggregates showed increasing trends, and organic C would accumulate in smaller soil aggregates. It further indicated that the addition of straw would affect the proportion of aggregate distribution and the contribution rate of organic C.
      Conclusion  The application of straw can improve soil aggregate stability and organic C content. The high fertility black soil combined with straw addition can improve soil organic C sequestration.

     

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