亚热带更新世沉积物发育土壤的特性和定量分类研究

Characteristics and quantitative classification of soils derived from pleistocene sediments in thesubtropics of China.

在野外调查的基础上,从土壤实体的属性出发,对分布于我国亚热带地区长江中下游丘陵阶地上、沉积年龄差距达几十万年、呈交叉分布的三类古老厚层运积母质——下蜀黄土、Q_2、Q_3红土上发育的23个代表性土壤剖面,作了较系统的室内分析和定量分类研究,目的是阐明这些土壤的发生学特性,明确它们的分类地位。通过对土壤颜色、颗粒组成、土壤酸度、电荷特性、土壤风化淋溶系数、粘粒和粉砂的硅铝率、铁形态组成、自然粘粒率、硅反应指标和硅饱和度指标等的分析。结果表明,这些中晚更新世沉积物发育的土壤的属性虽受现代成土条件的作用已产生了一定的变化,但在其形成的土壤中仍有明显残留的特点,母质对土壤性质有较大的影响。用数值分类和诊断分类等定量方法,可把本研究土壤分为四类。诊断分类与数值分类有74％的分类结果相同,但诊断分类还有一些不足之处。作者认为根据土壤属性进行数值分类是土壤分类的发展方向。

On the basis of field investigation, twenty-three representative soil profiles, derived from various pleistocence sediments and developed under the subtropic climate in the middle-lower reaches of the Yangtze River, are selected for the study. The primary objective of this study is to characterize those soils from the physical, chemical as well as mineralogical viewpoints and to analyze the genetic features in relation to their parent materials, and to classify quantitatively those soils based on their properies. The samples with each of horizons are collected for laboratory analyses from Hunan, Hubei, Anhui, Jiangxi, Jiangsu and Zhejiang provinces, including eleven soil profiles derived from middle-pleistocene red clay, three from late pleistocene red clay and nine from late pleistocene xiashu loess. Those parent materials were formed in the different period of the Quaternaty (that spaned approximately the past million years) with its varied history of geology, changing climate and vegetation successions. The results show that the soils derived from mid-late pleistocene sediments have developed under the influence of soil formation factors, but the pecuti-airties of the parent materials are still maintained and it would be possible to clarify the influence of the parent materials on the couse of soil development with respect to many properties, such as soil color, mechanical composition , pH, base saturation, charge properties , ba value, silica-alumina molar ratio of silt and clay , clay mineralogy, iron oxide forms , the index of silica reactivity and the index of silica saturation. Based on soil attributes, using comprehensive numical classification (including factor analysis, cluster analysis) and Chinese soil taxonomic classificaton, the soil under study are classified into four types, i. e. , yellow-brown soils, brown-red soils, para-red soils and red soils. 74% of classified results of numical classification are accordance with soil taxonomic classification, soil taxonomic classification has some disadvantages. Soil numeric classification is a direction of soil classification development.