海南岛土壤粘粒矿物特征与土壤系统分类

THE CHARACTERISTICS OF CLAY MINERALS IN THE SOIL OF HAINAN ISLAND AND THEIR APPLICATION IN SOIL TAXONOMICCLASSIFICATION

研究了海南岛不同母质土壤的粘粒矿物特征:都含有较多的高岭石,其中玄武岩发育土壤粘粒中高岭石最多,但其结晶最差。片岩和紫色砂岩发育土壤含相当多的水云母,粘粒部分水云母含量高达40％～45％,石灰岩发育土壤水云母含量亦较高,达20％～37％,此类水云母属二八面体型的水化白云母。玄武岩和花岗岩发育的“湿润”土壤粘粒中针铁矿与赤铁矿的含量之比为（3～4）:1,而花岗岩发育的“常湿”土壤粘粒中只有针铁矿,不见赤铁矿存在,证明土壤中氧化铁矿物的类型是土壤湿润状况的反应,在中国土壤系统分类中可以用来区分“湿润”和“常湿”土壤的一个指标。

The characteristics of clay minerals in the soils derived from different parent materials in Hainan Island and their application in Chinese Soil Taxonomic Classification are discussed in this paper. The results are as follows. In general, there are much kaolinite in the clay fraction of all soil samples, but the highest content and the worst crystaillinity of kaolinnite are present in the soils derived from basalt. The contents of hydromica are so much in the soils derived from schist or purple sandstone that they are as high as 40% -50% of the clay fraction. And the content of hydromica in the soil derived from limestone is also as much as 20% - 37% of the clay fraction. Moreover, the hydromica belong to hydromuscovite with dioctahedral structure. The ratio of the content of goethite and that of hematite is (3 - 4) : 1 in the clay fraction of the soils of 'udic' suborder derived from basalt and granite. But there is only goethite without hematite in the clay fraction of the soils of 'perudic' suborder derived from granite on the mountain. This result proves that the types of iron oxide in soil response to the soil moisture conditions, which can be used as an index to distinguish the udic and perudic soil moisture regime in the Chinese Soil Taxonomic Classification.