摘要
赣中丘陵第四纪红色粘土上发育的旱地红壤中粘土矿物的细粘粒(<0.001毫米)部分以高岭石和蛭石为主,并有一定量的水云母和夹层矿物。各级颗粒的化学组成中,随颗粒由粗到细,SiO_2的含量大体上也由高到低;Fe_2O_3的含量则是砂粒级稍稍超过粉粒级,后一情况与作者过去对太湖地区两种水稻土(白土和黄泥土)研究的结果相似。供试红壤粒径<0.005毫米的颗粒才显示抗压强度,而上述水稻土从<0.05毫米的颗粒就开始有抗压强度。同前所试水稻土一样,在供试红壤中,粒径<0.002毫米的颗粒开始表现出可塑性及膨胀性。
The red earths originated from Quaternary red clay are widely distributed in the hilly lands of central Jiangxi Province. Some physical and chemical properties of different particle size fractions of red earths were investigated. The main results are summarized as follows: 1. The clay minerals of the fine clay fraction (<0.001 mm) in the soils are predominated by kaolinites and vermiculites and contain some hydromicas and interlayer minerals. Distinct difference in the distributions of clay minerals was found between the coarse clay fraction (0.002—0.001mm) and the fine clay fraction (<0.001mm). 2. Chemical analysis of the samples showed that the content of SiO_2 decreased, but that of Al_2O_3 increased with the soil particles size fraction changing from coarse to fine, Which are consistent with the reported results by foreign pedologists. The sand fraction contained more Fe_2O_3 and had greater hygroscopicity and swelling capacity as compared with the silt fraction. These results are similar to those of bleached and permeable paddy soils in the Taihu basin, but different from forengn reports. 3. Plasticity and swelling were found only in the clay fraction (<0.002 mm). But in foreign reports these characters could be found in 0.005—0.001 mm particle fraction of some upland soils, and it might result also from < 0.002 mm fraction. 4. The compressive strength of red earth was found only in <0.005 mm size fraction, but that of paddy soils of the Taihu basin mentioned above was found in < 0.05 mm size fraction. It is considered that the plasticity and compressive strength have an obvious relationship with the content of fine clay in the paddy soils of Taihu, but these properties are weakened as a consequence of microaggregates with high stability formed by fine clay and sesquioxides in clayey red earth. Above-mentioned investigation is only a beginning for the study of the physical and chemical properties of different particle size fractions in upland soils of China. The experimental results may promote our understanding of the basic properties of soil particles, and supply a scientific basis for particles size fractionation and textural classification of soils in China.
出处
《土壤学报》
CAS
CSCD
北大核心
1990年第4期368-376,共9页
Acta Pedologica Sinica
