我国南方广泛分布着红壤和黄壤,这两类土壤,根据形态指标难于进行准确的类型划分.传统的土壤学认为,红壤和黄壤都是以富铝化为其成土特征,土壤胶体的SiO_2,Fe_2O_3,Al_2O_3含量和在土壤剖面中的分布则是这一成土特征的具体反映。一般认为黄壤的风化程度较红壤轻,因而硅铝率较红壤高。但从样品 Red soil and yellow soil are widely distributed in southern China, which are difficult to classify accurately according to their morphological indexes.Traditional soil science considers that both red soil and yellow soil are characterized by enrichment of alum into their soil, soil SiO 2, The contents of Fe 2 O 3, Al 2 O 3 and their distribution in the soil profile are the specific reflection of this soil-forming characteristic. It is generally believed that the degree of weathered yellow soil is lighter than that of red soil, and therefore the rate of silica-alumina is higher than that of red soil. But from the sample