亚热带山地草甸土性态的变异及其在中国土壤系统分类中的地位

Variation of Pedogenetic Characteristics of Mountain Meadow Soils in Subtropical Region of China and Their Placement in Chinese Soil Taxonomy

为了解我国亚热带地区山地草甸土性态的变化和成土特点,从福建、浙江、江西、安徽、湖南和贵州等省采集了20个代表性山地草甸土剖面,详细观察了土壤剖面形态特征,分析了土壤颗粒组成、有机质、阳离子交换量(CEC)、酸度、氧化铁形态和黏土矿物类型等指标,并从诊断分类的角度探讨了它们在中国土壤系统分类中的地位。结果表明:这一地区的山地草甸土表层有机质积累均非常明显,颜色普遍呈黑色和深褐色,土壤酸化明显,土壤氧化铁游离度多在40%以下,土壤CEC较高。但研究也发现,不同样点之间土壤的土体厚度、剖面构型、黏化状况、有机质垂直分布、氧化铁含量、矿物类型及其诊断层和诊断特性均有较大的差异。土体构型大致有Ah-C、Ah-Bw-C、Ah-Bt-C和Ah-G-C等4类。根据中国土壤系统分类的诊断标准,可把研究的20个剖面归并为均腐土、潜育土、淋溶土、雏形土和新成土等5个土纲,下续分为6个亚纲、10个土类和15个亚类。研究认为,在地理发生分类中笼统地把这些土壤归为一个土类存在边界不明确等问题。

To understand the spatial variations of pedogenetic characteristics and formation processes of mountain meadow soils in subtropical regions of China, 20 representative mountain meadow soil profiles were collected from Fujian, Zhejiang, Jiangxi, Anhui, Hunan and Guizhou provinces. Morphological characteristics of the soil profiles were observed in detail, and the particle composition, content of organic matter, CEC, acidity, forms of iron oxide and the type of clay minerals of the soils were characterized. Their types in Chinese Soil Taxonomy were determined according to diagnostic horizons and diagnostic characteristics of the soils. The results showed that the accumulation of organic matter in surface horizons of the soils was very obvious, and their color was generally black and dark brown with low brightness and chroma. Acidification of the soils was great and the free degree of iron oxide in the soils was mostly less than 40%, while soil CEC was relative higher. However, there were great differences in soil thickness, profile configuration, clayization, vertical distribution of organic matter, iron oxide content, clay mineral type, and diagnostic horizons and diagnostic characteristics among the soils. There were four types of soil configurations, i.e, Ah-C, Ah-Bw-C Ah-Bt-C and Ah-G-C. According to the diagnostic criteria of the Chinese Soil Taxonomy, the studied 20 soil profiles could be divided into 5 soil orders, i.e, Isohumosols, Gleyosls, Argosols, Cambosols and Primosols, and were further divided into 6 suborders, 10 soil types and 15 subtypes.