不同农业利用方式下湘南第四纪红壤的粘粒矿物学组成与表面电荷特性

用X-射线衍射分析技术和化学方法研究不同农业利用方式对湘南第四纪红粘土及其发育土壤的粘粒矿物学组成和表面电荷特性的影响．结果表明：湘南第四纪红壤的粘粒矿物组成以高岭石为主，其次是1．4nm过渡矿物．经过人为耕种尤其在水田条件下，蛭石和水云母的含量增加，铁的活化度增大．土壤表面电荷数量（CECpH3.2、CECp、CECv、AEC）和电荷零点（pH）的值也发生相应的改变．

Clay Mineral Composition and Surface Electric Characteristics of Quatemary Red Soils with Different AgriculturalUtilization Pattems in Southem Hunan Province

This paper deals with the effects of different land utilization patterns on clay mineral composition and surface electric characterishcs of Quaternary red soils in Southern Hunan provinces, by using X-ray diffraction techniques and electric chemistry methods. Results show that: (1) different agricultural utilization pattems have obvious influences on the physics and cbemistry properties of red soils. Aner anthropogenic mellowing, organic matter contents and P, K concentrations of the soils were me,end and the texture was improved.(2) Mineral composition of the parent materials included prevalent amount of kaolinite, then with 1.4 urn intergrade minerals and hydromica, little amount of vermiculite. Aner cultivation and fertilization, especially undder conditions of paddy field, contents of vermiculite and hydromica were increased and that of 1.4 nm intergrade minerals got decreased, which indicated that there possibly existed a reverse process of the weather sequence of minerals in conditions of soil anthropogtnic mellowing. (3) Free degree of iron in clay of those soils was generally more thari 80 percent. Aner cultivation and fertilization, espccially under conditious of paddy field, iron activity of those soils were increased, which indicated that an uncrystalling process probably existed under the conditions of soil mellowing. (4) Quatermary red soils in Southem Hunan Province were coexist systems of permanent charged surfaces with prevalent variable charged surfaces. After cultivation and fertization, AEC of the soil decreased. CECv of the soil increased, while CECP had no differences. (5) Zero point of charges (ZPC) of Quatermarh red clay in Southern Hunan province was 3.55, with that of upland larger than that of paddy field. and that of pasture land larger than that of uncultivated land. In paddy profiles, ZPC of soil in opper layer was greater than that of lower layer.