College of Resources and Environment, Hunan Agricultural University, Changsha, 410128, China.
Sci Rep. 2021 May 6;11(1):9707. doi: 10.1038/s41598-021-89049-y.
Clay minerals are intermediate products generated during soil development, and their neoformation and transformation are closely related to pedogenesis. Here we aimed at identifying the difference in the clay mineral composition of upland soils derived from different parent materials and different soil-forming environments and exploring the importance of clay mineral composition in pedogenesis and soil taxonomy. We sampled 60 soil B horizons in Hunan Province of subtropical China by digging soils derived from granite (GR), slate and shale (SS), Quaternary red clay (QRC), limestone (LS), and sandstone (SDS). The clay mineral composition and its correlation with parent materials, elevation, micro-topography, and pedogenic processes were investigated using X-ray diffraction and Pearson's correlation analysis. The clay mineral was dominated by kaolinite, followed by 2:1-type minerals (illite and vermiculite), and a small fraction of mixed-layer minerals. The composition of soil clay minerals varied with parent materials. Kaolinite was predominant in soils derived from GR and LS; mixed-layer minerals prevailed in QRC, whereas illite and vermiculite were prevalent in SDS. In addition, elevation and micro-climate could also explain the variations in clay mineral composition. Increase in elevation was associated with decreased 1:1 clay mineral content and increased 2:1 clay mineral content, especially in soils developed from LS. The composition and content of clay minerals indicated that Ferrosols, Ultisols, and Acrisols had undergone intense weathering; Primosols, Entisols, and Leptosols were characterised by weak weathering, and Plinthic Ali-Udic Cambosols, Plinthudults, and Plinthosols were characterised by strong redox status. This study suggests that clay mineral composition is related to the parent material, climate, and micro-topography, and that it can serve as an indicator of pedogenesis and soil type in subtropical China.
粘土矿物是土壤发育过程中的中间产物，其新形成和转化与成土过程密切相关。本研究旨在确定来源于不同母质和成土环境的旱地土壤的粘土矿物组成差异，并探讨粘土矿物组成在成土作用和土壤分类中的重要性。我们通过挖掘来自花岗岩（GR）、板岩和页岩（SS）、第四纪红土（QRC）、石灰岩（LS）和砂岩（SDS）的土壤，在亚热带中国湖南省采集了 60 个土壤 B 层样品。使用 X 射线衍射和 Pearson 相关分析研究了粘土矿物组成及其与母质、海拔、微地形和成土过程的关系。粘土矿物以高岭石为主，其次是 2:1 型矿物（伊利石和绿泥石），还有一小部分混合层矿物。土壤粘土矿物的组成随母质而变化。GR 和 LS 来源的土壤以高岭石为主；QRC 以混合层矿物为主，而 SDS 则以伊利石和绿泥石为主。此外，海拔和微气候也可以解释粘土矿物组成的变化。海拔升高与 1:1 粘土矿物含量减少和 2:1 粘土矿物含量增加有关，特别是在 LS 发育的土壤中。粘土矿物的组成和含量表明，富铁土、强淋溶土和酸性土经历了强烈的风化；始成土、淋溶土和雏形土的风化较弱，而潜育性富铁土、潜育性粘盘土和潜育性粘磐土的氧化还原状态较强。本研究表明，粘土矿物组成与母质、气候和微地形有关，可作为亚热带中国成土作用和土壤类型的指标。
