陕西黑垆土在中国土壤系统分类中的归属

在分析陕西省境内9个黑垆土剖面成土环境、剖面形态特征及理化性质的基础上,按照中国土壤系统分类高级及基层分类检索标准,确定了其在中国土壤系统分类中的归属。9个黑垆土剖面的腐殖质层厚度介于30～120 cm,通体均具有强石灰反应,CaCO_3含量介于12.5～189.5 g/kg,其中6个剖面具有30～45 cm的堆垫层。黑垆土共包括淡薄表层、暗沃表层、雏形层、黏化层、钙积层5个诊断层和堆垫现象、钙积现象、盐积现象3个诊断现象,均腐殖质特性、温性土壤温度状况、半干润土壤水分状况以及石灰性4个诊断特性。9个黑垆土剖面在高级分类上可检索为淋溶土和雏形土2种土纲,向下继分为普通钙积干润淋溶土、钙积暗沃干润雏形土、钙积简育干润雏形土以及普通简育干润雏形土4个亚类;其土族鉴别特征可分为黏壤质混合型温性、壤质硅质混合型石灰性温性、壤质混合型温性等6个土族以及胡家庙系、崾崄系、崔木系等9个土系。但目前的系统分类检索结果未能体现黑垆土具有深厚腐殖质层及堆垫现象的典型特性,因此黑垆土的系统分类归属仍需开展深入研究,同时建议新增堆垫干润雏形土土类或堆垫简育干润雏形土亚类,以体现人为农业生产活动对黄土高原地区土壤的影响。

Attribution of Dark Loessial Soils in Chinese Soil Taxonomy in Shaanxi

Dark loessial soil, charactering with a deep humic layer, was an important agricultural soil in the Loess Plateau, and it was developed from natural soil formation process as well as intensive agricultural production activity. In this paper, 9 typical profiles of dark loessial soil were selected, field soil survey was conducted, morphological characteristics of soil profiles were observed physicochemical properties of horizon samples were measured, diagnostic horizons and diagnostic characteristics were determined and soil taxonomy were decided for the studied soil profiles. Theresults showed that deep humus layers of 9 dark loessial soil profiles were identified with the thickness of 30~120 cm, and strong calcaric reactions were found with the CaCO3 content ranged from 12.5 g/kg to 189.5 g/kg, simultaneously, 6 of the 9 profiles were characterised by artificial surface accumulation during agricultural activities with the cumulic layer ranged from 30cm to 45cm. For the selected dark loessial soil profiles, 2 diagnostic surface horizons (ochric epipedon, mollic epipedon), 3 diagnostic subsurface horizons (argic horizon, calcic horizon and cambic horizon) and 7 diagnostic characteristics (calcaric property, isohumic property, salic evidence, mesic soil temperature regimes, ustic soil moisture regimes, cumulic evidence and calcic evidence) were determined. One soil profile was sorted into Ustic Argosols and 8 profiles were sorted into Ustic Cambosols. Only one subgroup (Typic Calcic-Ustic Argosols) was attributed for the Ustic Argosols, while three subgroups (Calcic Mollic-Ustic Cambosols, Calcic Hapli-Ustic Cambosols and Typic Hapli-Ustic Cambosols) were attributed for the Ustic Cambosols. According to the criteria for establishment of soil families and soil series in CST, 7 soil families (clay loamy mixed type mesic temperature-Typic Calcic-Ustic Argosols, loamy mixed type mesic temperature-Calcic Hapli-Ustic Cambosols, etc.) and 9 soil series (Hujiamiao series, Yaoxian series, etc.) were established of the selected soil profiles. However, the sorted results of the studied soil profiles based on CST did not revealed the essential characteristics of deep humus layer and cumulic evidence for the dark loessial soil, therefore further researches are needed to emphasized soil taxonomy of the dark loessial soil, so we suggested that the subgroup of Cumulic-Hapli-Ustic Cambosols or the subgroup of Cumulic-Ustic Cambosols been added in the CST in order to further reflect the effects of human agricultural activities on soil formation in the Loess Plateau.