Chapter I. The history of the study of soil types in the World is shortly noted and the present state of the investigations on that direction in Japan are briefly explained. The author threw the questions how to define and characterize the brown earths for the field works in our country. Chapter II. The characteristics of the brown earths given by Ramann are restated and the criticisms against that soils type by some authors are interpreted. The selected profiles and their explanations of the soils known as the brown earths in European Continent, British Islands and North America are described with the author's short critical notes. On the comparative study of the given materials, the author came to recognize Ramann's brown earths with little modifications, especially on the soil reaction Chapter III. The essential points of the characteristics of the brown earths are given, on considerations of the data in Europe and America with reference to the soils of our country. The brown earths are dividen into the normal and degraded ones, the latter being very slightly podsolized, but retaining the characteristics of the normal ones in greater degrees. The author distinguishes the forest and the glassland brown earths, as the podsols are divided into the forest and the meadow podsols in Europe. The glassland brown earths resemble the prairie earths in some respects and occupy the glassland developed originally or after the destruction of forest in remote past times. Finally the author called attention to the importance of the further investigations of this sub-type of the brown earths. (Jan., 1934).

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The study of soil has been researched not only from the view point of colloidal chemistry, but also from more over the soil forming process which from the dynamic view point through the soil profile, since so-called the theory of climatic soil zone has been advocated by DOKUCHAIEV, SIBIRTSEV, GLINKA, RAMANN and others. And also in Japan, much results on the weathering process have been published, but also there is nothing on it in San'in-district. So therefore the authors carried out the following examination. The samples were taken from Kumagasen (Height 300m), Tottori-ken, Hinogun, Kanagawa-mura, Kawagasaki. A) 3-10cm Contained raw humus, so-called Profile A_0. This profile was not taken in our examination. B) 20-100cm brownish yellow, not contained humus, so-called Profile A. For our convenience' sake this layer was described as Profile I. C The layer under Profile I holded the structure of mother rock, so we could distinguish it from Profile I, but the boundary of the two layers was not obvious. The sample was taken from the place of 200 cm under Profile I. We described this layer as Profile II. (D) Under the microscope, mother rock contained quartz and biotite as main component, less feldspar and graphite as secondary component, and more or less apatite. Therefore we could consider this rock as Graphite biotite schist. The result of total analysis by Jakob's method is shown in Table I and according to HARRASSOWTTZ the weathering co-efficient calculated from the result of total analysis shows that Biotite schist in San'in-district has received the wathering process of Kaoline. HCI soluble portion in Profile I and II is shown in Table III, and the result of SiO_2/Al_2O_3,Base/Al_2O_3 and exchangeable acidity by KCl method are shown as follows. [table] SiO_2/Al_2O_3 in clay portion was 1.65 in Profile I and 1.67 in Profile II. So we could consider that the weathering process in San'in-district was not typical Laterization process, but it might be the process which was taken in high temperature and much moisture reason. By Gedroiz and Bobko's method we determined the absorptive capacity, the amount of H-ion and the exchangeable base, and by Hissink's method the saturation degree was determined as shown in the following tables. [table] The amount of free alumium soluble in 10% Na_2CO_3 was determined by Seki's method, and its amount in Profile I was in between Brown soil and Red soil and the amount in Profile II was almost as Same as in Brown Soil, comparing with the result denoted by STEBUTT. (Table XII) And also according to HARASOWITZ, Biotite-schist in San'in-district has received so-called his "Allitic weathering process." Lang's Ragenfaktor and Meyer's N-S Quatient in San'in-district are calculated as follows. [table] Now we can sum up as follows, (1) This examination is the study on the weathering process of Biotite-schist in San'in-district, Japan. (2) Biotite-Schist in Sani-district may receive so-called Harrassowitz' Allitic weathering process. (3) In the climatic soil type, this soil belongs to the medium soil type, transitional from Brown soil, between Brown soil and Red soil. (4) The value of Lang's Ragenfaktor is not agree with the result of chemical analysis and the observation in the field. (5) Meyer's N-S Quatient in Hamada shows that the Brown soil may be appear in San'in-district, but N-S Quatient in Sakai and Miyadu intimate the other type of soil may be obvious.

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Five varieties of Soybeans one of which is larger grained than the others, were investigated as to their manure value and found : (1) By sowing the same volume of seeds in the same area and matured, a large grained variety contained much more N, P_2O_5,K_2O and also dry matter than the other per plant, but the crop as a whole, no marked difference was found among them and in some cases the fine grained varieties surpassed the other ; (2) The fine grained varieties contained more N, P_2O_5 and K_2O in their grains than the other but in their leaves, the reverse was true, and not much difference was found in the stems and pods ; (3) On an average, the leaves of these five varieties of beans contained 18% N, 8.3% P_2O_5 and 25% K_2O of the total elements contained in the plant, and since the bean plants shed their leaves on maturity, it is evident that these elements are returned to the soil ; (4) 20% or more of the organic matter of the bean plants is returned to the soil by the fallen leaves if the beans are harvested on maturity.

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Soils from the tea farms in Siduoka Prefecture which belong to various soil system were investigated as to their exchangeable acidity (after DAIKUHARA), pH (by quinhydrone) and Mn content (by colorimetric method of WILLARD and GREATHOUSE, 1917) and found : (1) The highest and lowest exchangeable acidity were 174.6 and 0 respcctively ; (2) pH ranged 3.80-6.0 and mostly 4.5 ± ; (3) Quantity of Mn varied from trace to 2.5% (Mn_2O_3) and generally 0.1-0.8% with a few exception ; (4) No definite correlation between the acidity and Mn content was fonnd ; (5) Neither direct qualitative nor quantitative relation between the tea crop and the acidity was noted so far as this investigation is concerned.

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Nine sorts of leguminous plants, Genge, saat-wicken, snail-clover, alfalfa, lupine, horsebean, hairy-vetch, lathyrus (Martimus) and lespedeza, cultivated as green manure with the exception of last two, were analysed upon the methods proposed by WAKSMAN, TENNeY and others, modified in several respects. The plant constituents were grouped conveniently as follows : (1) ether soluble fraction. (2) cold water soluble fraction. (3) hot water soluble fraction. (4) 2% hydrochloric acid fraction. (5) 80% sulphuric acid fraction. (6) residual materials. For conclusion, the authors had a discussion with regard to the results obtained from the above analysis, from point of view such as the ratio of water soluble nitrogen to total nitrogen, concerned to the rapidity of decomposition of plant materials as green manure.

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