不同施肥处理黑土覆膜后秸秆碳氮在团聚体中的固存特征

地膜覆盖是提高作物产量的重要措施，理解覆膜条件下黑土团聚体中外源碳和氮的固存特征，为深刻认识地膜覆盖措施的可持续应用提供理论依据。选取长期定位试验站(29年)不施肥(CK)、单施化肥(NPK)和有机肥配施化肥(MNPK)3个典型施肥处理，表层土壤(0—20 cm)添加¹³C¹⁵N双标记玉米秸秆后设置裸地和覆膜的田间原位微区培养试验，探讨不同施肥处理结合覆膜黑土团聚体中有机碳和全氮对秸秆来源碳和氮的响应。结果表明，与裸地相比，所有处理覆膜后微团聚体(<0.25 mm)中秸秆来源碳和氮的含量平均降低了26.49%和32.05%。覆膜MNPK与裸地处理相比大团聚体(>0.25 mm)中秸秆来源碳和氮的含量显著降低了35.58%和15.97%,但大团聚体中原土壤有机碳的含量提高了9.16%。在CK和NPK处理微团聚体中，秸秆来源碳占该粒级团聚体有机碳的比例表现为覆膜>裸地，而在MNPK处理各粒级团聚体中则表现为裸地>覆膜。无论覆膜与否，秸秆来源碳对团聚体有机碳和秸秆来源氮对团聚体全氮的贡献率受施肥处理的影响表现为CK>N...

Sequestration characteristics of straw residue carbon and nitrogen in aggregates following plastic film mulching on Mollisols with different fertilization treatments

Plastic film mulching is an important agricultural practice to improve crop yields and ensure sufficient food supply for the growing population. But the improvements in soil moisture and temperature under plastic film mulching stimulate the mineralization and loss of soil organic carbon. Any increase in crop yields must not be at the expense of soil quality. Studying the sequestration characteristics of newly added carbon and nitrogen in Mollisol''s aggregates after plastic film mulching is crucial for the sustainable application of plastic film mulching. We collected topsoil samples (0-20 cm) from three fertilization treatments (no fertilization application, CK; inorganic fertilizer, NPK; and inorganic fertilizer plus manure, MNPK) at a 29-year long-term Mollisol experiment in Northeast China. We then mixed three fertilized soil samples with ¹³C¹⁵N double-labeled maize straw, and conducted a 900-day in-situ micro-plot incubation experiment without (bare) and with plastic film mulching. The objective of this study was to understand how plastic film mulching modified the dynamics of straw residue carbon and nitrogen incorporation into soil aggregates under various fertilizer management strategies. The results showed that compared with Mollisols of three fertilizer management strategies under bare conditions, plastic film mulching decreased straw residue carbon and nitrogen contents by 26.49% and 32.05% among the microaggregates (<0.25 mm), respectively. As for the MNPK treatment under bare conditions, plastic film mulching significantly decreased straw residue carbon and nitrogen contents by 35.58% and 15.97% in the macroaggregates (>0.25 mm), but increased native soil organic carbon content by 9.16% in the macroaggregates. Plastic film mulching increased the contribution percentage of straw residue carbon in organic carbon of the CK and NPK treatments among the microaggregates, when compared to that of corresponding bare conditions. But in macroaggregates and microaggregates of the MNPK treatment, the contribution percentage of straw residue carbon in organic carbon was significantly lower under plastic film mulching conditions than that under bare conditions. Regardless of bare or plastic film mulching, the contribution percentage of straw residue carbon in organic carbon and straw residue nitrogen in total nitrogen in macroaggregates and microaggregates were affected by fertilizer management strategies, and the contribution percentage of straw residue carbon and straw residue nitrogen in both aggregates decreased in the order of CK > NPK > MNPK. Moreover, the contribution percentage of straw residue carbon in organic carbon and straw residue nitrogen in total nitrogen in microaggregates were larger than those in macroaggregates. Overall, plastic film mulching promoted the renewal of organic carbon in the microaggregates of the NPK treatment; while in the MNPK treatment, plastic film mulching accelerated the loss of straw residue carbon and nitrogen in macroaggregates and microaggregates, it also played a positive feedback effect on the accumulation of native soil organic carbon among the macroaggregates.