A three-year field experiment was conducted to analyze the effects of straw enrichment and deep incorporation on the humus composition and the structure of humic acid (HA) in black soil. The differences in the HA structure between different straw returning methods were detected by three-dimensional fluorescence spectroscopy and ¹³C NMR technology. The purpose of this paper is to provide a theoretical basis and data support for improving the straw returning system. Four different treatments, including no straw applied (CK), straw mulching (SCR), straw deep ploughing (MBR), and straw enrichment and deep incorporation (SEDI: harvested the corn straw from four rows together with a finger-plate rake and then crushed and buried them in one row in the 20∼40 cm deep level in the subsoil with a wind-driven input cylindrical plough), were used in this study. Our results showed that compared to CK treatment, SEDI significantly increased the contents of organic carbon (SOC), soil humic acid carbon (HAC), fulvic acid carbon (FAC), and humin C content (HM-C) in the subsurface soil layer by 27.47%, 34.33%, 19.66%, and 31.49%, respectively. Among all the straw returning treatments, SEDI treatment had the most significant effect in increasing the contents of HEC, HAC, and FAC. Straw returning not only reduced the degree of condensation and oxidation of the HA structure but also increased the proportion of alkyl C and enhanced the hydrophobicity of the HA structure in subsurface soil. Moreover, SEDI treatment significantly increased the proportion of aliphatic C/aromatic C of the HA structure in subsurface soil and improved the aliphatic property of HA, which had a significant effect on the HA structure compared to other treatments.

中文翻译：

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不同玉米秸秆还田模式下黑土中HA的荧光光谱和13C NMR光谱特征

进行了为期三年的田间试验，分析了秸秆富集和深度掺入对黑土腐殖质成分和腐殖酸 (HA) 结构的影响。采用三维荧光光谱法检测不同秸秆还田方式HA结构的差异，¹³C核磁共振技术。本文旨在为完善秸秆还田制度提供理论依据和数据支持。四种不同的处理方式，包括不施秸秆（CK）、秸秆覆盖（SCR）、秸秆深耕（MBR）和秸秆富集深掺（SEDI：用指板耙从四行收获玉米秸秆，然后在本研究中使用风驱动输入圆柱犁将它们压碎并埋入地下 20 至 40 厘米深的水平面中。我们的结果表明，与CK处理相比，SEDI显着增加了地下土壤层中有机碳（SOC）、土壤腐植酸碳（HAC）、富里酸碳（FAC）和腐植酸碳含量（HM-C）的含量分别为 27.47%、34.33%、19.66% 和 31.49%。在所有秸秆还田处理中，SEDI处理对提高HEC、HAC、FAC含量的效果最为显着。秸秆还田不仅降低了HA结构的缩合和氧化程度，而且增加了烷基C的比例，增强了HA结构在地下土壤中的疏水性。此外，SEDI处理显着增加了地下土壤中HA结构的脂肪族C/芳香族C的比例，改善了HA的脂肪族性质，与其他处理相比，对HA结构有显着影响。