福井県の主要畑土壌の粘土鉱物組成

抄録

The clay mineral composition of seven upland field soils in Fukui Prefecture, a lithsol, an andosol, four brown forest soils and brown lowland soil, was discussed based on the results of X-ray diffraction technique, thermal analyses and infrared absorption spectrometry. The outline of the results is as follows: Chlorite-vermiculite intergrade, mica clay minerals and gibbsite, and kaolin minerals were dominant in three brown forest soils, respectively. A small amount of pyrophyllite or talc existed in a brown forest soil originated in the andesitic sediments. Chlorite was dominant, and serpentine, derived from the parent rock, was also found, in the brown lowland soil. The andosol contained large amounts of amorphous materials and mica clay minerals. Mica clay minerals and chlorite were dominant in the clay fraction of the lithosol. This result shows that the clay mineral compostion is not influenced with the soil types but with the parent rocks, under the natural condition of soil genesis in Fukui Prefecture. The distribution phase of clay minerals, especially 2: 1-type minerals such as vermiculite, in the soil horizon was rather similar to yellow-brown forest soils in the warm temperate region of south west Japan than podzolic soils.