广西紫色土系统分类研究

Studies on taxonomy of Guangxi purple soil

采用中国土壤系统分类的理论、方法和标准,结合广西第二次土壤普查资料数据,研究了广西紫色土剖面形态特征、理化特性及系统分类。结果表明,广西紫色土是强烈的物理、化学风化及侵蚀作用于紫色砂岩、砾岩、泥岩和页岩的结果,其剖面层次分异不明显,多属块状结构,质地以砂壤为主;其自然土壤的有机质、全氮、全钾含量均处于中上水平,但在植被遭到破坏及经开垦后,表层土壤的有机质、全氮及速效磷含量均明显下降,pH值变幅较大,呈强酸至弱碱性;广西紫色土可划分为雏形土和新成土2个土纲、湿润雏形土和正常新成土2个亚纲、紫色湿润雏形土和紫色正常新成土2个土类以及表蚀紫色湿润雏形土、耕淀紫色湿润雏形土、酸性紫色正常新成土等9个亚类。

The taxonomic,morphological and physico-chemical characteristics of purple soils profile of Guangxi have been studied using the theories,methods and standards of Chinese soil taxonomy combined with data obtained during second soil survey of Guangxi.The results showed that the formation of purple soil of Guangxi was the result of the effects of physical and chemical weathering and erosion on purple sandstones,conglomerates,mudstones and shale.The differentiation of purple soil profile was not significant and most of the purple soil had blocky structure with sandy loam texture.The contents of organic matters,total N and K in natural soil were found above average levels.However,the contents of organic matters,total N and available P in surface soil decreased significantly with great variability in pH ranging from 4.0-8.5.The purple soil of Guangxi could be classified into two soil orders（Cambosols and Primosols）,two suborders（Udic Cambosols and Orthic Primosols）,two soil groups（Purpli-Udic Cambosols and Purpli-Orthic Primosols） and nine subgroups（Trunic Pupli-Udic Cambosols,Agric Pupli-Udic Cambosols,Dystric Pupli-Orthic Primosols,etc.）.