岷江上游杂谷脑河谷土壤发生特征与系统分类研究

为了解岷江上游杂谷脑河谷的土壤发生特征及类型归属，以位于四川阿坝藏族羌族自治州理县杂谷脑河谷的8个典型土壤剖面为研究对象，通过野外成土因素调查与土壤形态特征观测及室内土壤物理、化学性质分析，依据《中国土壤系统分类检索(第三版)》(简称系统分类)与《中国土壤(1998)》(简称发生分类)鉴定其类型。研究表明，8个剖面均为温性土壤温度状况、半干润土壤水分状况；土壤色调为7.5YR和10YR，部分剖面表层明度和彩度均低于3.5，达到暗沃表层的颜色要求；土壤颗粒组成以粉粒含量最高、砂粒次之、黏粒最低，质地为壤土或粉质壤土；土壤结构主要为亚角块状，部分剖面表层为团粒结构；部分剖面中具有腐殖质、黏粒胶膜及假菌丝体等新生体，形成黏化层和钙积层；均具石灰性，主要为碱性到强碱性反应；有机碳含量范围1.64 ~ 61.45 g/kg，部分剖面含量至上而下逐渐降低，具有均腐质特性；游离铁含量为10.78 ~ 19.57 g/kg，个别剖面B层均在14 g/kg以上，具有铁质特性；有效磷含量为1.2 ~ 43.1 mg/kg，个别符合肥熟表层和磷质耕作淀积层的有效磷含量要求。供试土壤在中国土壤系统分类中归属于人为土、均腐土、淋溶土和雏形土4个土纲的4个亚纲、7个土类和8个亚类，在中国土壤发生分类中属于半淋溶土纲下褐土土类的燥褐土亚类(对应于系统分类的石灰肥熟旱耕人为土、普通简育干润雏形土和普通暗沃干润雏形土3个亚类)及石灰性褐土亚类(对应于系统分类的普通暗厚干润均腐土、普通简育干润淋溶土、钙积暗厚干润均腐土、普通钙积干润淋溶土和普通铁质干润淋溶土5个亚类)。中国土壤系统分类具有更强的土壤类型区分能力。

Genetic Characteristics and Taxonomy of Soils in Zagunao Area in Upper Reaches of Minjiang River

A total of 8 typical soil profiles were selected as study objects, which are located in the Aba Tibetan and Qiang Autonomous Prefecture in Sichuan to explore genetic characteristics and taxonomy of soils in Zagunao Valley in the upper reaches of the Minjiang River. Through field survey of soil forming factors, the observation of soil morphological characteristics, and lab determination of soil physiochemical properties, soil types were determined according to Chinese Soil Taxonomy (CST) and Chinese Soil Genetic Classification (CSGC). Results showed that all the 8 soil profiles are of mesic temperature regime and ustic moisture regime. Soil hue is 7.5YR and 10YR, the values and chromas of some topsoils are lower than 3.5, meeting the color requirements of Mollic Epipedon. Silt fraction is the highest and clay fraction is the lowest, with the texture of loam or silty loam. Soil structures are mainly of sub-angular block, and the topsoils of some profiles are of aggregate structure. Moderate humic substances, clay film and CaCO₃pseudomycelium are found in some layers, indicating the existence of Argic and Calcic horizons. All soils have Calcaric property, mainly with alkaline to strongly alkaline reactions, and the content of calcium carbonate equivalents is ranged from 66 to 133 g/kg. The content of soil organic carbon is ranged from 1.64 to 61.45 g/kg, showing a gradual decrease with the increase of soil depth in some profiles and indicating the existence of Isohumic property. Free iron oxide content is reached from 10.78 to 19.57 g/kg and is over 14 g/kg in some layers, indicating the existence of Ferric property. Olsen-P content is reached from 1.2 to 43.1 mg/kg and meets the requirements of Fimic epipedon and Agric horizon in some layers. In CST, the studied soils are belonged to 4 orders of Anthrosols, Cambosols, Argosols and Isohumisols, 4 Suborders, 7 Groups and 8 Subgroups; while in CSGC, they are belonged to Dry-brown soil subgroup of Cinnamon soil group of Semi-leached soil order (corresponding to Calcaric Fimi-Orthic Anthrosols, Typic Hapli-Ustic Cambosols and Typic Molli-Orthic Cambosols in CST) and Calcareous brown soil subgroups of the same group and order (corresponding to Typic Pachi-Ustic Isohumosols, Typic Hapli-Ustic Argosols, Calcic Pachi-Ustic Isohumosols, Typic Calci-Ustic Argosols and Typic Ferri-Ustic Argosols in CST). Thus, comparatively, CST has stronger ability to distinguish soil types compared with CSGC.