A series of pot experiment with wheat were conducted to elucidate the possible promotion of phosphate availability by soil conditioners. Krilium 9,6,Aerotil and Na-humate were applied in three different placements as illustrated, in Fig. 1. In block placements similar to band placememt in practical fields, the concentration of soil conditioners undoubtedly increased around fertilizers as compared with the apparent percentages. In general, the growth and yield of wheat were evidently improved when the concentrations of soil conditioners were expected to be high enough to actually present phosphate fixation, as reported in the previous paper (Part 1) (cf. Table 1-4). The ultimate reason was attributed to the surprisingly increased uptake of phosphoric acid by wheat plant as shown in Table 5 & 6,although the uptake of N and K more or less increased. The result may suggest a new promising application of soil conditioners, not directly aiming at the improvement of physical condition of soil but directly connected with the improvement of chemical properties i. e. prevention of phosphate fixation.

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Effect of organic acid exuded from crop roots, upon mineralization of organic phosphorus in soils were investigated this time, and the results were as follows : 1. Crop roots, especially their caps, were observed to liberate continuously their surface cells into culture solution (Photo. 1 and 2). Rate of this liberation was so different with respect to plants as in the following order, Gramineae≫Leguminosae>Solanaceae. 2. By paper chromatography, cell sap of roots was recognized to contain organic acids, such as oxalic acid, succinic acid, malic acid, tartaric acid and citric acid. By the same chromatography, oxalic acid was traceable and tartaric acid as well as citric acid were found in a small amount in ether extract from nutrient solution, in which a large number of sweet potato shoot had been cultured. 3. Na salts of α-oxyacid (tartaric and citric acids), when added to soil, increased the solubility of organic phosphorus, originally contained in, and newly added to, the soil. This increase was mainly due to the solvent action of oxyacids but not due to the change of pH of the soil (Table 2 and Fig. 1). 4. Addition of oxyacids to soil promoted the mineralization of organic phosphorus, when the soil was incubated. This promotion was considered to be caused by the increased solubility of organic phosphorus due to addition of oxyacid and by the increased pH of soil and, at the same time by the accelerated activity of soil microbes by the supply of new carbon source (Table 3 and Fig. 2).

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(1) The principal rock-forming minerals and rock-grains found in Koyama and Shimohojo sand-dune soils in Tottori district, are quartz, microcline, orthoclase, oligoclase, augite, hornblede, hypersthene, biotite, magnetite, ilmenite, zircon, apatite, ferruginous quartz, quartzite, siliceous slate and chert. (2) From the observation on the relative stability. to weathering of rock-foming minerals and rock-grains found in surface layers (0〜10 cm in depth) and underlaying layers (90〜100 cm in depth) of Koyama and Shimohojo sand-dune soils, a weathering sequence (ordered in stability in every category) of these minerals and rock-grains was presumed as follows : Most stable : quartz, zircon. Stable : magnetite, ilmenite, apatite. Moderatly stable : hornblende, augite hypersthene, quartzite, chert, ferruginous quartz, siliceous slate. Least stable : microcline, orthoclase, oligoclase, biotite.

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1. The translocation and distribution of P^<32> and Ca^<45> were examined by autoradiograph, using wheat and tomato. According to these results, the former was accumulated in the plant parts, where metabolic activity was vigorous, but the latter was distributed uniformly throughout the whole parts of plant. 2. The difference of translocation and distribution of P^<32> and Ca^<45> could be ascertained also by autoradiograph ; and we obtained the same result as in our previous report.

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The distributions of free oxides along the profiles of dry rice fields in polder lands of the Kojima-basin, Okayama Pref. are reported. Localities, numbers of years elapsed after the planting of rice began in each field and the characteristics of soil profiles are given in Table 1. All the field are of a dry rice field except A, and have barley or wheat as winter crops. Parent materials are similar in all horizons of all soils and rich in fine particles. The structures develop well. Free oxides were determined by the Mg-reduction method, as illustrated in Fig. 1.

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It has been said that the rice plant roots would be able to oxidize hydrogen sulfide. which was generated in the paddy soil, by its oxidative action. Of this oxidation; we studied the autoxidation of hydrogen sulfide in the water culture solution. (1) The rate of oxidation of hydrogen sulfide was accelerated by addition of iron. and the maximum effect of this acceleration was observed in the culture solution of about pH 7. These results indicated that the oxidation of hydrogen sulfide occurred through the formation of Fe-H_2S intermediate complex : and the reaction of culture solution controlled the formation of this intermediate complex. (2) Oxidation of hydrogen sulfide in the culture solution was accelerated by the planting of rice plants. It would be seen that the effect of this planting was mainly due to the iron compounds precipitated on the root surface. The root surface was the active locality where hydrogen sulfide was oxidized. (3) It was considered, from these results, that there was competitive consumption of oxygen in culture solution between root respiration and hydrogen sulfide oxidation : and the harmful effect of hydrogen sulfide on the rice plant growth was partially caused by the deficiency in oxygen in accordance with the autoxidation of hydrogen sulfide.

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In Paper chromatographic procedures for mixtures including both cations and anions, it has already been found that mutual interference between cations and anions takes place in their movement on the chromatogram. H. T. GORDON et al. have pointed out that polyvalent anions exert an unfavorable influence upon the movement of cations on the paper. Unfortunately, any appropriate technique for arrest of such interactions has not yet been ascertained. Since the total amount of anions in hot HCl-extracts of common soils is much less than that of cations, it can be expected that even if a soil extract is applied on a paper without prior separation of both ions from one another, the interference between cations and anions may be minimized by means of certain modifications of the chromatographic procedure. The present investigation was therefore undertaken to determine the effect of HCl-concentration in the developer which consists of 1 vol. HCl versus 9 vol. acetone, the time required for developing Rf-values, the degree tailings, and the separabilities of Fe, Al and P in their mixtures. From the experiment with soil extracts it was conclusive1y found that the most favorable condition, to prevent the interference and to promote the separation, was of the concentration of 8N HCl in the developer and of 4 hrs. for developing. Under those conditions, Rf-values of various elements involved were 0.94 for Fe, 0.01 for Al, 0.58 for P, 0.36 for Mn, 0.67 for Cu, 0 for Mg, 0 for Ca. 0 for K, and 0.5 for Si, respectively. Percentage errors of the values obtained by this procedure from soil extracts were -14 to +26% for Fe. -19 to + 27% for Al, and -34 to +2% for P in the case of the direct method which estimates visually on colored chromatogram, while -3 to +9 % for Fe, -10 to +12% for Al, and much more for P in the indirect method which determines colorimetrically after extraction of spot parts on chromatogram. From above results it was confirmed that this procedure was suitable for the determination of Fe and Al, except P, in soil extracts. The outline of the method, recommended here, is as follows : Extract 25 g soil with 75 ml HCl according to ordinal method, decompose organic materials in the extract by addition of HNO_3,and evaporate to dryness. Dissolve the residue without silica separation into 10 ml HCI and make up to 250 ml with water (original solution). In the case of direct method, dilute an aliquot of the original solution to 20-fold volumes. Apply 2/100ml of this dilution for Fe, 1/100ml for Al, while 1/100ml of the original solution for P. Then make chromatogram for 4 hrs. by the developer containing 8 N HCl acetone, 1 : 9 in vol., developing the color of each element in order to be compared visually with color standards. On the other hand, in the case of indirect method, prepare three paperstrips applied to each 2/100 ml of the original solution, and develop the color together in one tube under the same condition as above described. At first, develop the color for each element on one of them. Refering the position of color on one of the three strips, each element is extracted from two other strips by dil. HCl. In this extract, determine the content of each element by means of colorimetry.

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In reference to the previous report, in this paper, we investigated the effet of "Arashi" to the chemical and physical properties of paddy field soil in Ando soil area of low yield. The results obtained were as follows : (1) "Arashi" seemed to change chemical and physical properties of the paddy soil in accordance with the kind of geological formation. (2) With the above treatment (Arashi), a large amount of humus in the Ando soil was changed into the rotted product, and true humic acid was decreased. This product seemed to raise the productive power of the field. (3) On the other hand, free iron oxide relatively decreased, the rotted product was decomposed, and hydrogen sulfide was developed; consequently an increase of rice-yield in this Ando soil was not necessarily expected.

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In reference to the investigation on reversion of ferric to ferrous iron in paddy soils under waterlogged condition, an attempt was made to establish a rapid method for determining Fe^<++> and Fe ^<+++> in soil. The principle of the method was as follows : After Fe^<++> and Fe^<+++> in the soil were dissolved in hot 3N H_2SO_4 solution, Fe^<++> in the solution was determined colorimetrically by use of α, α'-dipyridyl. Then Fe^<+++> in the solution was determined, after it was reduced by the ammoniacal solution, saturated with sulfur dioxide. The results of the determination, according to this procedure, satisfied well author's purpose. From the results it was shown that : (1) After a larger part of easily reducible Fe^<+++>, was reduced to Fe^<++>, there was a rapid increase in sulfide. (2) A correlatin was observed between the lowering of Eh_7 and the increase of ratio of Fe^<++> to Fe^<++>+Fe^<+++>. From this correlation , the easily reducible iron compound in the soil appears to be one of the dynamic component of "electroactif" substances, buffering soil oxidation -reduction potential.

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Four clay fractions (<0. 15μ, <0.6μ, 0.6〜1.0μ, 1.0〜2.0μ) and medium silt fraction (9〜11μ) were separated from a surface layer of a relatively poor drainage paddy soil (pH=4.90) derived from an alluvium of Abukuma River. They were investigated by chemical analysis, differential thermal analysis, and X-ray diffraction method. The following facts has been clarified through the result of our experiments. In the colloidal fractions (<0.15μ and <0.6μ), dioctahedral mixed-layer minerals predominates, accompanying small amount of halloysite, diocta-vermiculite, and illite. In the coarse clay fractions (0.6〜1.0μ, 1.0〜2.0μ), quartz and cristobalite, trioctahedral 2 : 1 type minerals (palygorskite) would predominate, and the same clay minerals as those in the finer fractions are also found to be lesser extent. In a silt fraction (9〜11μ), quartz, cristobalite, and palygorskite exist, and some chlorite and sepiolite are also supposed to be present.

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