In the previous report, writers recognized that water and free phosphoric acid were important factors on the conversion to available magnesium, and the presence of about 15 per cent water and several per cent free phosphoric acid increased largely both amount and speed of this conversion. Now the effect of serpentine particle size on conversion to available magnesium was studied. On the experiment, the serpentine was classified to the samples as 30〜50,50〜70,70〜100,100〜150 and 150< meshes. These materials were analysed according to the procedure given in the 1st report. Sixteen mesh ordinary superphosphate (Table 1,a) was mixed with classified serpentine (Table 1,b) in the 6 : 1 proportion; and water was added to these five mixtures to 15 per cent, respectively. Total, 2 per cent citric acid soluble and water soluble MgO and P_2O_5 were determined after 1,7,14,21 and 56 days curings at 29℃, while being compared with the change of pH value (Table 2). The results obtained are summarized as follows : 1. Increase of pH value was proportional to the fineness of serpentine particle size. 2. Amount and speed of the conversion to available magnesium also were proportional to the fineness of serpentine particle size. 3. The conversion of magnesium was satisfied, when the fineness of particle size was 70 mesh pass.

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In this paper the authors investigated the variance of height and number of stem of rice plant, and also considered the relation of sample size and reliability, comparing some sampling methods. (1) The variance of height and number of stem are almost constant in various species and in various stage of growth expecting every early stage of growth. The standard deviation of rice plant is 3〜5 (cm) in height, 2〜3 in number of stem, so the deviation is 5〜7% of its height and 20〜30% of its number of stem. (2) The relation of sample size and confidence interval of height and number of stem are considered in one sample field in which the deviation and mean are already known. Results are shown in Table 3. From this results the confidence interval at ten sample size is X^^- ± 2.2(α=10%) in height, X^^- ± 1.7 in number of stem, so that the comparision of growth from this sample size has considerable risk. Between plots to detect 1 cm difference of height 120 samples must be investigated. But it seems that the investigation of 15〜30 samples is sufficient for ordinary field experiment of rice plant. (3) Three sampling method-simple random sampling, stratified random sampling and systematic sampling-are compared. 10 samples are sampled by each method from the field, and calculated the confidence interval. It is interesting problem that the systematic sampling method, which is most easy for resarch workers, has not necessarily low reliability.

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EDTA ou trilon B (l'ethylenediamine tetraacetate de disodium) est connu comme un compose ayant des remarquables proprietes complexant avec des elements metalliques (Ca, Mg, Mn, Ba etc). Schwarzenbach et ses collaborateurs ont etudie les comportements de ces complexones par la methode chimique et physico-chimique. Aujourd'hui, trilon B est, en effet, utilise comme un reactif dans la chimie analytique et aussi dans la chimie industrielle et biologique. Nous avons essaye l'application du trilon B (EDTA) a l'etude du sol pour dosage des bases bivalentes. Magnesium et calcium sous formes des bases echangeables sont facilement doses a l'EDTA; mais dans cette methode preconisee, il faut tenir compte de quelques etats d'essai. 1) Les etudes preparatoires. i) Mg^<++> et Ca^<++> sont doses assez bien a l'aide de ce reactif en presence d'EBT (Eriochrome black T, le noir eriochrome T) (pH=10.1,tamponne par NH_4Cl-NH_4OH) et Ca^<++> est dose en presence de murexide (pH=12.0,tamponne par 1 N-KOH). Dans le premier cas, Mn^<++> peut aussi former un complexe stable avec EDTA-EBT que l'on permet a doser (Tab. 1,2), ainsi que il est necessaire que Mn^<++> soit degage de la reaction. A cet egard, nous avons obtenu un resultat satisfaisant en appliquant la 6 N-solution de (NH_4)_2S qui parfaitement precipite Mn comme MnS et encore n'influence pas sur le dosage de Ca^<++> et Mg^<++> a la temperature ordinaire (Tab. 4,5), tandis que, au chauffage, un mauvais resultat est donne. ii) A cote de l'emploi de (NH_4)_2S, une autre methode est a recommender au dosage du Mg^<++> et Ca^<++> sans influence du Mn^<++>. Ce procede est comme suivant : Mn^<++> peut etre facilement dose par la methode d'apres Murakami (oxydation de Mn^<++> a MnO_4^- par le peroxide d'argent). Il en resulte que la teneur precise en Mg^<++>+Ca^<++> s'obtient par difference entre deux chiffres obtenues : 1° par EDTA-EBT (Mg^<++>+Ca^<++>+Mn^<++>), 2° par colori metrie (Mn^<++>). iii) Fe^<+++>, Al^<+++> et PO_4^<---> (surcharge de Fe^<+++>) sont aussi precipites par (NH_4)_2S en donnant un resultat satisfaisant au dosage (Tab. 6). En outre, ils peuvent etre precipite par NH_4OH en neutralisant sans indicateur. 2) Dosage du magnesium et calcium echangeable des sols. i) Deplacement par l'acetate d'ammonium. 10g de terre sont lessives par une solution normale d'acetate neutre d'ammonium (500 cc) d'apres Schollenberger et Dreibelbis (Nous avons modifie un peu le lessivage ou le rapport du volume de la solution a la terre d'essai est plus grand que dans la methode originale). La solution recueillee est ajoutee de HCl et evaporee a sec au bainmarie, puis le residu est traite au bain de sable par un peu de HCl en presence d'eau oxygenee pour detruire la matiere organique et reprise par l'eau distillee legerement chlorhydrique (la volume d'echantillon : 200〜250 cc). ii) Titrage par l'EDTA-Il suffit d'ajouter au milieu tamponne par NH_4Cl-NH_4OH (pH=10.1) ou KOH (pH=12.0) ou s'effectue le dosage (10〜20 cc de prise d'essai), quelques gouttes de l'EBT (chez notre etude, cinq gouttes) ou une petite dose (0.2 g) du murexide pulverise par K_2SO_4 et de titrer avec l'EDTA jusqu'au virage. Dans le premier cas, il y a virage du rouge vineux au bleu; dans le dernier, du violet rouge au violet bleu. iii) Le dosage du magnesium et calcium se fait per la methode d'EDTA-EBT, tandis que manganese est dose par colorimetrie (Leitz : compensating photometer, filtre S. 51)-oxydation de Mn^<++> a MnO_4^- par le peroxide d'argent dans le milieu acide a 8〜12% H_2SO_4. iv) Cette methode s'effectue sur les sols japonais donne un resultat satisfaisant (Tab. 7,8), mais

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This experiment is a preliminary work to explore the organic acid metabolism of paddy rice plant. Leaf blades (50 g) of paddy rice in a head sprouting period were sampled on a fine day morning. These leaves were instantly homogenized by Waring Blender and mortar, then filtered through cheese-cloth. The filtrate was centrifuged at 3000 r.p.m. for 30 minutes. Sediments were dealt with cation exchanger, and then centrifuged. Both supernatants of centrifugations above mentioned were put together, then dealt with anion exchanger under an analogous method to that of BRYANT et al. Acid fraction thus obtained (3.17 m eq.) was exactly neutralized and concentrated under reduced pressure. Half of this acid mixture was chromatographed on a silica gel in the BULEN et al's method. Obtained chromatogram is shown in Fig. 3. The other half of the acid fraction was chromatographed on another column of silica gel containing no sulfuric acid. This chromatogram is shown in Fig. 4. Fig. 1 is a typical chromatogram obtained with a mixture of several pure acids and Fig. 2 is that of BULEN et al. By comparing with Fig. 1 and 2,each fraction of Fig. 3 and 4 may be roughly identified, however, this estimation cannot be conclusive. Then the authors undertook the procedure of paper chromatography to verify the estimation. Table 1,2,and 3 show the results of such paperchromatography. From these experiments, it is conceived that the following organic acid are conclusively contained in leaf-blade of matured rice-plant. 1) Lactic acid 2) Oxalic acid 3) Succinic acid 4) Fumaric acid 5) Malic acid 6) Citric acid.

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In studying the fulvic acid fraction of paddy soil, the existence of so-called β-fraction (WAKSMAN'S) comes into question. In the paddy soil at the several experimental stations, the writer could see the decrease of β-fraction with the increasing amount of dressing farmyardmanure. It seems that its decrease depends upon the Al_2O_3 in fulvic acid which is decreased by the increase of farmyardmanure. When the fulvic acid is fractionized into four fractions by FORSYTH'S absorption technique, almost all Al_2O_3 and Fe_2O_3 are in Fraction A, isolated from organic matter, and in other fractions no β-fraction is formed. It seems that β-fraction is the organic matter co-precipitated when the Aluminium precipitated, and its amount depends on the Aluminium amount in the fulvic acid fraction.

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Experiments were made with the soils, alluvial, volcanic ashy and mineral acidic. Conditioner, applied in 0.1% of the soil, caused the soil to aggregate 4〜5% of its amount (see Table 1). Soli aggregate (0.25 mm<), by conditioner, had somewhat higher absorptive power for phosphoric acid (see Table 2). Conditioner became more effective with an increase of applied amount (see Table 3). By the addition of Krilium (0.15% of soil) soil was somewhat protected from its being washed down (see Table 1).

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Parent materials of the soils are unsolidified shalely gravels originated from deluvial deposit (Yashiroda form.). Because of a large quantity of winter snow which melts out in warm spring at one time, it is obscure to estimate the climatic factors participate in the weathering process. For instance mean annual temperature is 19℃. excluding four months from Dec. to Mar. Annual rainfall is 2670.8mm. Then LANG'S Rain-factor becomes 140.5. On the flora, Pinus densiflora is dominate. Humus content of surface soils is somewhat rich. The colour of subsurface soils is light yellowish brown to dark yellowish red. Soil reactions are strongly acid and the degree of base saturation is very low. SiO_2/R_2O_3 of the colloidal clay is about 1.0〜2.0. The amounts of free iron oxide and free alumina are fairly large. But there is no marked indication influenced by the podosolization. I consider that these soils may be grouped as a yellow or red soil.

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Following the previous report, the author studied the visible and ultraviolet absorption spectra of humic acids in alkaline solutions, which were extracted from paddy rice soils, peats and rotten stump by SIMON'S method. The results are summarized as follows : 1. Absorption curves (log κ-λ curves) of these humic acids were very similar in their shape; and the intensity of light absorption increased generally toward the shorter wavelengths. The curves were nearly straight (Fig. 1). 2. When these curves were expressed on the same concentrations of humic acids (0.01% solutions), they were generally not crossed; and there existed a reciprocal relationship between the intensity of light absorption coefficient at a given wavelength and the inclination of the curve to the axis of wavelength. (Fig. 2 and Table 1) 3. Humic acids having smaller light absorption had a weak absorption band in the ultraviolet region, but this band was not found in the case of those having stronger light absorption (Fig. 1). From these results, it may be reasonably said that the mechanism of light absorption of humic aicds is essentially the same, and the intensity of their light absorption corresponds to their degree of humification, that is, the latter can be shown by their absorption spectra.

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Results, here summarized, are of soil survey, made in Kiga-cho. Of the survey, soil classification was made on soil profile. Soil types (after European idea), spreading in arable area of Kiga-cho, numbered eight in the following way. I. Zonal soil types. (Vegetation soil type). Reddish brown Soil. II. Azonal soil types. Mountain soils, Colluvial soil. III. Intrazonal soil types. (Ground water soil types). Half-bog soils, Meadow soil (River-bed types), Meadow soils, Gray lowland soils, Brown lowland soils. These 8 soil types have been classified in detail into 57 kinds by their morphological characters (See Table 1). Of soil types spreading in forest land, orchard and upland field, 5 kinds were of Mountain soils, one, Colluvial soil, and one, Reddish brown soil. Of soil types spreading in the paddy area, 8 kinds were Half-bog soil; 8 kinds, Medow soil (River-bed type); 27 kinds Meadow soil; 7 kinds, Gray lowland soil; and 3 kinds, Brown lowland soil. Basing on the results of the soil survey, the map of soil types in Kiga-cho was made (See Fig. 1).

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Amount of crop in regions, where a transferring cultivation between paddy and upland fields is practiced, is always greater than that in regions, where rice plant is the only crop. To study the reasons for this increase, a soil survey of 16 regions, both types of cultivation where practiced was made. The redox potential of soils and the effects of drying were measured in the laboratory. Of the studies, we found the following results : (1) The experiment was carried on in four different types of soil; peat, muck, clay and sand. In the one crop fields, there was a reduction of the pan that was originally present in all four types of soil; in the transfer-cultivation fields granular structure developed in all four types of soils. (2) Samples of the non-air dry soils were flooded for three weeks at 25℃., and the redox potential were measured : in the one crop paddy fields the fall of the Eh was rapid, and except for the muck soil the degree of fall was low, but in the transfer-cultivation fields the fall was slow and the degree of fall was comparatively high, and the Eh differed with soil types in both fields. (3) The effect of drying was greater on the one crop paddy fields than on the transfer-cultivation paddy fields, but differed in its degree with the soil types.

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The purpose of our studies is to investigate the process of the formation of principal paddy soil types in Japan by the following means, a) observation of soil profiles, b) estimation of general chemical and physical characteristics, c) identification of primary and secondary minerals, d) identification of the type of soil humus. In this paper the distributions of free oxides in several soil profiles are reported. These paddy soils are all evidently affected by acid humus derived from heavily dressed raw orgaic matters, their drainages are good and parent materials are cherty somewhat accompanied with shales and volcanic ashes. The characteristics of soil profiles are given in Table 1 and mechanical compositions in Table 2. Each soil is rich in gravels and porous throughout the profile. The structure is well developed. Much organic matter is found in every horizon and free Fe_2O_3 is broadly accumulated in subsoils. All the horizon presents brown, dark brown or blackish brown colour. Free oxides are determined by Mg-reduction method modified JEFFRIES' Mg-ribbon-potassium-oxalate method. The results are given in Table 3. As to profile A, free oxides intensely move from the surface soil to the lower part. There is a maximum accumulation of free Fe_2O_3 in the second horizon and free Mn_3O_4 in the third horizon and free Al_2O_3 in the fourth horizon. Free TiO_2 is equally found in all the horizons except the top horizon. Profile B and C are similar to A, but as to B the maximum accumulations of free Mn_3O_4 and Al_2O_3 are found in the same horizon. And as to C the maximum accumulations of free Fe_2O_3 and Mn_3O_4 are found in the third horizon. In all three profiles, the maximum accumulation of free Al_2O_3 are always found below that of free Fe_2O_3. The movement of free Al_2O_3 is characteristically different compared with that in the paddy soils, of which surface soils are not affected by acid humus. Results in these soils shall be reported in the latter part. The amounts of free Fe_2O_3 and Mn_3O_4 determined by different methods are compared. The results are given in Table 4 and 5. In the accumulation horizon, the ratio free Mn_3O_4/total Mn_3O_4 is higher than the ratio free Fe_2O_3/total Fe_2O_3. But in the surface soil the ratio free Mn_3O_4/total Mn_3O_4 is lower than that of iron. It seems to be because of rapid removal of free Mn_3O_4 from the surface soil to the subsoil. The amounts of free Al_2O_3 determined by Mg-reduction method are compared with the values of ascension of pH by NaF-treatment. The results are given in Table 6. The pH of the accumulation horizon of free Al_2O_3 is ascended to above 10 after 24 hours keeping at 24℃ by addition of N/2 neutral NaF. The value of ascension of pH in the maximum accumulation horizon of free Al_2O_3 is the highest in both A and B. The amounts of free TiO_2 are compared with those of conc. HCl soluble and total TiO_2. The results are given in Table 7. Total TiO_2 in both bulk samples and ignited samples are estimated. The results are given in Table 8. The movement of titanium in paddy soils is hardly found. There are the different horizons in total TiO_2 content which seem to be probably because of the difference of alluvial materials.

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