秸秆全量还田下沼液替代化肥对潮土团聚体及结合有机碳的影响

Effects of Chemical Fertilizer Substituted by Biogas Slurry on Aggregates and Associated Organic Carbon Characteristics in Fluvo-aquic Soil under Total Straw Incorporation

    摘要
  • 摘要:
      目的  通过探究黄淮海平原秸秆全量还田条件下长期沼液替代化肥对潮土水稳性团聚体及结合有机碳影响，以期为改善土壤结构，增加土壤有机碳积累及推动种养结合循环农业发展提供科技支撑。
      方法  采集长期持续进行不同沼液替代化肥处理（不施肥对照，CK；单一施用沼液，BS；单一施用化肥，CF；以及沼液半量替代化肥，BSCF）的表层（0 ~ 20 cm）土壤，利用湿筛法分离水稳性团聚体并测定不同粒径团聚结合有机碳分布变化情况。
      结果  相较于对照，各施肥处理均能显著增加了外源有机碳投入，增加水稳性大团聚体质量组成比例，提高团聚体稳定性，其中沼液半量替代化肥处理 > 0.25 mm粒径水稳性团聚体质量组成比例提升效果最为明显，平均重量直径和几何平均直径最高，而团聚体破碎率和分形维数最低。不同处理团聚体结合有机碳含量随粒径增加表现出先升高后降低的趋势，其中以0.25 ~ 2 mm粒径最高。同时各施肥处理均增加各粒径团聚体结合有机碳含量，显著提高 > 0.25 mm粒径大团聚体结合有机碳贡献率，降低 < 0.053 mm粒径粘粉粒结合有机碳的贡献率。
      结论  在黄淮海平原秸秆全量还田条件下通过沼液半量替代化肥不仅有利于水稳性大团聚体的形成和团聚体稳定性的提高，达到改善土壤结构的目的，而且能够调控各粒径团聚体结合有机碳贡献率，达到平衡土壤有机碳的维持和养分的释放目的。

     

    Abstract:
      Objective  To explore the effects of chemical fertilizer substituted by biogas slurry on characteristics and associated organic carbon (C) of water-stable aggregates in fluvo-aquic soil based on total straw returning, field experiment was conducted to improve soil structure and organic C sequestration as well as the combination of farming and animal husbandry.
      Method  Soil samples from different treatments (no fertilizer control, CK; biogas slurry application alone, BS; chemical fertilizer alone, CF; half substitution chemical fertilizer by biogas slurry, BSCF) were collected and separated by wet sieving method and corresponding aggregate associated organic C was determined.
      Result  All fertilization treatments significantly increased exogenous organic C inputs and mass composition proportion of water-stable macro-aggregates and improved aggregates stability. The greatest WR0.25, mean weight diameter (MWD) and geometric mean diameter (GMD) were obtained in the treatment of half substitution chemical fertilizer by biogas slurry, which also acquired the lowest percentage of aggregate destruction (PAD) and fractal dimension (D). Aggregate associated organic C contents increased all firstly and then decreased with size increasing and reached the highest in the particle size of 0.25-2 mm. Meanwhile, all fertilization treatments increased aggregate associated organic C contents of different fractions, and organic C contribution rate of aggregates more than 0.25mm at the expense of reducing contribution rate of soil particles less than 0.053 mm.
      Conclusion  Chemical fertilizer substituted by biogas slurry not only improved water-stable macro-aggregates formation and stabilization, but also balances soil organic C maintenance and nutrient release by adjusting organic C contribution rate with different aggregate fractions.

     

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