The structure of soil pores plays a crucial role in determining the distribution and retention of particulate organic matter (POM) within soil aggregates, yet the specific effects of different straw return practices on POM stabilization through soil pore structure remain poorly understood. This study aimed to quantify and visualize soil macroaggregates POM distribution and pore structure using advanced X-ray computed tomography (CT) and image processing techniques under three straw return practices: no-tillage with straw mulching (NTS), traditional rotary tillage with straw incorporation (RTS), and deep plowing with straw incorporation (DPS) in a Vertisol. A total of 27 soil aggregates (4–6 mm) from soil depths of 0–10, 10–20, and 20–40 cm were analyzed at an 8-μm resolution. The results showed that NTS significantly increased POM content and surface area density in the 0–10 cm soil layer compared to RTS. In contrast, DPS was most effective in deeper soil layers (20–40 cm), maintaining high POM content and promoting the development of extensive and well-connected pore networks, as evidenced by significantly higher connected porosity and mean breadth density of POM. Additionally, strong positive correlations were observed between POM content, connected porosity, and pore connectivity (P < 0.05). These findings highlight the importance of selecting appropriate straw return practices to optimize POM retention and enhance soil C storage, particularly in the context of sustainable soil management in Vertisols.

中文翻译：

---

使用 X 射线计算机断层扫描量化和可视化各种秸秆还田实践下 Vertisol 中的土壤大团聚体孔隙结构和颗粒有机质


土壤孔隙的结构在决定土壤团聚体中颗粒有机质 （POM） 的分布和保留方面起着至关重要的作用，但不同的秸秆还田做法对通过土壤孔隙结构稳定 POM 的具体影响仍然知之甚少。本研究旨在使用先进的 X 射线计算机断层扫描 （CT） 和图像处理技术在三种秸秆还田实践下量化和可视化土壤大团聚体 POM 分布和孔隙结构：免耕秸秆覆盖 （NTS）、传统旋耕秸秆掺入 （RTS） 和深耕秸秸掺入 （DPS） 在 Vertisol 中。以 8 μm 的分辨率分析了 0-10、10-20 和 20-40 cm 土壤深度的总共 27 个土壤团聚体 （4-6 mm）。结果表明，与 RTS 相比，NTS 显著提高了 0–10 cm 土层的 POM 含量和表面积密度。相比之下，DPS 在较深的土壤层 （20-40 cm） 中最有效，保持高 POM 含量并促进广泛且连通良好的孔隙网络的发展，POM 的连通孔隙率和平均宽度密度显着升高证明了这一点。此外，POM 含量、连通孔隙率和孔隙连通性之间观察到强正相关 （P < 0.05）。这些发现强调了选择适当的秸秆还田做法以优化 POM 保留和增强土壤 C 储存的重要性，尤其是在 Vertisols 可持续土壤管理的背景下。