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.

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In the Tertiary region in Mamurogawa Town, Yamagata Prefecture, striking differences in relief and soil distribution were found between volcanic and sedimentary rock mountains. Mountains composed of rhyolite, andesite, and so on, undulate strongly. The slopes on them are steep, and they are occupied widely by Lithosols, Regosols and Eroded Soils. On the contrary, mountains composed of mudstone, tuff, and so on, undulate gently. These slepes are gentle, and they are occupied widely by Brown Forest Soils and Black Soils. In short, soils are immature on volcanic mountains and mature on sedimentary mountains. Great differences in soil physical properties are found between the two type of mountains. Namely, soils are gravelly or sandy and packed loosely on volcanic mountains, however they are clayey and packed compactly on sedimentary mountains. Among the latter, soils are packed most compactly on mountains composed of Tozawa mudstone. This seems to be influenced by the differences in lithology and relief between the two types of mountains. On the contrary, no significant differences in chemical properties are found between the two mountains. It was considered that the expected differences were concealed due to aeolian deposits mixed into soil parent materials on both mountains.

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To clarify the effects of the temperature at the humus extraction with diluted sodium hydroxide (0.5% NaOH) on the characteristics of the humus extracted, the characteristics of the humus extracted from the residue of the extraction at 30℃ with hot (100℃) NaOH were examined for various kinds of soils from Japan: typic Kuroboku soils; Light-colored Kuroboku soils; Red-yellow soils; Brown forest soils; Gray low land soils; Peat soils etc.. Total yields of the humus extracted by the above successive extraction were nearly equal to those by single heating extraction (100℃, 30mm.). This indicates that the humus extracted with a hot diluted NaOH solution is composed of the two fractions with different solubilities on extraction temperature, namely, soluble in diluted NaOH at 30℃ and at 100℃. Amounts of the humus extracted from the residue of the extraction at 30℃ with hot NaOH were 13 to 51% of total soluble humus, less in typic Kuroboku soils (Melanudands) than the other soils; that is, the average yield of the second heating extraction were about 20% for the typic Kuroboku soils and 40% for the other soils, respectively. The amounts of humic acid (HA) fraction of the second heating extract was less than that of the first room temperature extract for the typic Kuroboku soils, while for the other soils the HA of both extracts were nearly same. For all soil samples, however, the HAs of second heating extract were characterized by much lower optical absorbance at 600 nm, or, lighter color than those of the first room temperature extract. Further, FT-IR spectra of the HAs of second heating extract were characterized by very strong CH absorption at 2920 and 2850 cm^<-1>, and also by the strong absorbances assigned to polysaccharides and amides etc.. This result indicated that the HAs of the second heating extract was more aliphatic or less aromatic in its characteristics than those of the first room temperature extract. It seemed that the humus with more aromatic charateristics is dissolved more easily into the dilute NaOH than those which are more aliphatic. Heating at the extraction of soil humus with dilute NaOH solution causes not only an altemation of the humus extracted, but also the additional extraction of the humus which is different in its characteristics from those extracted under room temperature.

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