Pseudo-sands are soil microaggregates with less than 1 mm diameter that are not dispersible in water even after 16 h of shaking treatment. The physical stability of pseudo-sands against dispersion may affect the extent to which organic matter is retained in the soil, particularly in Oxisols where pseudo-sands occur throughout the A and B horizons. It is not completely understood the pedological chain of events behind the development of such strong physical stability of pseudo-sand and its effects on the turnover of organic matter found inside the microaggregates. To address this issue, we review the theories about the genesis of pseudo-sands in Oxisols. This review was conducted to support future studies on microaggregate formation and mineral-organic associations in Oxisols. The genesis of pseudo-sands in Oxisols is attributed to the following processes: (i) residual accumulation of pedogenic Fe- and/or Al-(hydr)oxides that weld kaolinite particles; (ii) linkages between Fe- and/or Al-(hydr)oxides, kaolinite, and organic matter, which increase cohesive forces among clay particles and create pore-space area; (iii) mechanical fracturing of mineral materials by long-term wetting-drying and erosion-deposition cycles; and (iv) long-term bioturbation that reduces size and increases physical stability of aggregates that are modified by soil mesofauna (e.g., ant and termite) to construct chambers and mounds. The magnitude of each of these four processes should vary as a function of soil depth, parent material, erosion-deposition dynamic, and vegetation-driven bioturbation intensity. The retention of organic carbon in Oxisols is more efficient when mineral-organic associations are backed up by the physical protection provided by occlusion of organic matter inside the pseudo-sands. Future investigations should determine to what extent the internal structure (e.g., intra-aggregate pore tortuosity) of pseudo-sand causes the separation of organic matter from microbes/decomposers and creates a physical barrier that decreases oxygen availability or oxygen/water ratios to decomposers.

伪砂是直径小于1毫米的土壤微团粒，即使经过16 h的摇晃处理也无法分散在水中。伪沙对分散的物理稳定性可能会影响有机物在土壤中的保留程度，特别是在A和B层遍及伪沙的土壤中。还没有完全理解假砂如此强的物理稳定性的发展背后的事件学事件链及其对微骨料内部有机物周转的影响。为了解决这个问题，我们回顾了有关Oxisols中伪砂成因的理论。进行此审查是为了支持对Oxisol中微骨料形成和矿物-有机缔合的未来研究。Oxisols中伪砂的成因归因于以下过程：（i）焊接高岭石颗粒的成岩Fe和/或Al-（氢氧化）氧化物的残留积累；（ii）铁和/或铝（氢）氧化物，高岭石和有机物之间的联系，这增加了粘土颗粒之间的内聚力并产生了孔隙空间；（iii）通过长期的湿法干燥和腐蚀沉积循环机械破碎矿物材料；（iv）长期生物扰动，可减小被土壤中生动物（例如蚂蚁和白蚁）改性的骨料的尺寸并增加其物理稳定性，从而建造小室和土墩。这四个过程中每个过程的大小都应随土壤深度，母体材料，侵蚀沉积动态和植被驱动的生物扰动强度而变化。当通过伪砂内部有机物的阻塞提供的物理保护来支持矿物-有机缔合时，在有机质中保留有机碳的效率更高。未来的研究应确定假砂的内部结构（例如，聚集体内部的曲折度）在多大程度上导致有机物与微生物/分解剂分离，并形成物理屏障，从而降低了氧气的利用率或分解剂的氧气/水比。