湘东第四纪红色黏土发育的典型土壤在中国土壤系统分类中的归属

Attribution of Typical Soils Derived from Quaternary Red Clay of Eastern Hunan in Chinese Soil Taxonomy

选取湖南省东部地区12个由第四纪红色黏土发育的典型土壤剖面,在对其成土环境、剖面形态特征及其理化性质进行研究的基础上,按照中国土壤系统分类方案,检索出了其诊断层和诊断特性,据此确定了其在中国土壤系统分类中的归属。结果表明,供试土壤剖面包含了淡薄表层、暗瘠表层、低活性富铁层、黏化层、聚铁网纹层等10个诊断层和诊断特性,其在中国系统分类体系中的位置分别为:淋溶土、富铁土和雏形土3个土纲;湿润淋溶土、湿润富铁土和湿润雏形土3个亚纲;简育湿润富铁土、铝质湿润淋溶土和铝质湿润雏形土3个土类;暗红简育湿润富铁土、表蚀简育湿润富铁土、网纹简育湿润富铁土等6个亚类;按照土族和土系划分标准,建立了黏质高岭石型酸性热性-普通铝质湿润淋溶土等9个土族和燕塘系(43-LY01)等12个土系。研究发现:受亚热带气候影响,许多土壤剖面发生了富铁铝化过程,且由于淋溶强烈,形成了聚铁网纹层,而现行的《中国土壤系统分类检索(第三版)》还不能给出一个合适的位置,因此建议在铝质湿润淋溶土亚类中增设一个可以反映相关特性的网纹铝质湿润淋溶土亚类。

By investing soil forming environment, profile morphological characteristics and physico-chemical properties of 12 typical soil profiles derived from Quaternary red clay in eastern Hunan Province, this paper examined the diagnostic horizon and diagnostic characteristics of these soils in Chinese Soil Taxonomy （CST） and defined their types of soil family and soil series. The results showed that there are 10 diagnostic horizons and characteristics such as Ochric epipedon, Umbric epipedon, LAC-ferric horizon, Argic horizon, Plinthic horizon in the 12 soil profiles. According to CST, they belong to 3 orders such as Argosols, Ferrosols, and Cambosols; 3 suborders like Udic Argosols, Udic Ferrosols and Udic Cambosols; 3 groups as Hapli-Udic Ferrosols, Ali-Udic Argosols and Ali-Udic Cambosols; and 6 subgroups as Rhodic Hapli-Udic Ferrosols, Trunic Hapli-Udic Ferrosols, Plinthic Hapli-Udic Ferrosols, etc. In addition, according to the Classification Standards for Soil Family and Soil series of CST, 9 soil families and 12 soil series were defined for the 12 profiles. The result showed that under the impact of subtropical monsoon climate, many soil profiles are ferrallitic. Due to the intensive leaching, plinthic horizon has been formed. However, no appropriate position can be found for such characteristics in CST, therefore, it suggested that a mew subgroup of Plinthic Ali-Udic Agrosols reflecting related characteristics should be added in CST.