The authors examined the path of movement of phosphate after having been absorbed through leaf surface of tomato directly by the use of radioautography. Tomato plant, about 30 cm high, was applied on one of the leaves with ca 1/50 M potassium dihydrogen phosphate containing P-32 (120 micro curie/ml). After 24 hours of the application, the petiole of the applied leaf and the stalk were sampled. In the stalk, decisions were made at two positions where are 1 cm above and below the attaching point of the petiole. Each section, 50μ thick, was pressed between filter paper and cellophane (lOμ thick) by hot iron. On this dried preparate, Fuji stripping film ET-2E was decked with the intermediation of the cellophane, then they were hold between two slide-glass, covered with black paper and then exposed for 20 days in an desiccator. By this procedure, watersoluble phosphates contained in the preparate would be able to remain as they are. Radio-autography thus prepared are shown in Plate 2,4 and 6. Compared each of them with Plate l, 3 and 5 respectively, the following results may be withdrawn : l) Foliar absorbed phosphate (P-32) is accumulated first into vascular bandle. At petiole it was found almost in phloem tissue, then moved downward to the stalk. 2) At the petiole it was found that P-32 was also accumulated in outer layer of cortex and epidermis in addition to vascular bandle. 3) P-32 which had been introduced into stalk, moved downward chiefly through phloem, however a little P-32 was found in xylem. 4) At upper part of stalk, on the contrary, much P-32 was found in xylem, especially in primary vessels, rather than in phloem.

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The irregularities in the nodule production-kinship between nodule bacteria and legumes were discussed from the points of strain of rhizobia, kinds of legume and environmental condition. The cross-inoculation group may be accepted inpite of WILSON's proposal that such group should be abandoned, but it is to be considered not in a strict sense, but in such meaning that it is the grouping of legumes depending upon the degree of affinity between legume and rhizobia or the range of strains by which each legume is nodulated.

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The micro-aggregates which were usually known in concerning to the deggregation of soil crumbs or the aggregation of single particles of soils had not been investigated for details. In this paper the authers reported the size distribution and durability of secondary particles as follows : (1) The diameters of secondary particles were from 0.06 mm to 0.02 mm. Two peaks were in the distribution-curves; and the diameter of larger particles were two times as larger as that of the smaller. (2) The durabillity of water-stable aggregates could be designated as follows; W=A/t^b (or log W=a-b log t). W=soil fraction larger than 0.06 mm (or 0.02 mm), t=time of shaking. (3) Cultivation or air-drying of soils decreased the degree of water stability of soil crumbs. (4) Sub-soils (B-horizon) did not disperse to the diameter as less than 0.02 mm. This was a typical characteristic of sub-soils, different from top-soils (A-horizon).

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In this paper, the mechanism of phosphate-release from Manganous, Calcium and Magnesium phosphaes by humic acid was studied by the same method as reported previously. The results are summarized as follows; (1) Humic acid prevents the precipitation of phosphates by Mn^<++>, Ca^<++> or Mg^<++> at various pH values, but the humates formed with those bases have the tendency to adsorb the soluble phosphates reversely in the acidic range such as pH 5〜6. (2) The mechanism of phosphate-release from Mn-, Ca- and Mg-phosphates by humic acid might be similar to that from Fe- or Al-phosphates by humic acid, as the humic acid accelerates the hydrolysis of Mn-, Ca- or Mn-phosphates. (3) The effective action of humic acid in preventing phosphate precipitations from soluble phosphates or releasing soluble phosphates from insoluble phosphates may be ascribed to the formation of humates with Fe(OH)_3,Al(OH)_3 or such bases as Mn^<++>, Ca^<++> and Mg^<++>.

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The loss of nitrogen by direct volatilisation of ammonia transformed from urea was studied in relation to the amount of urea applied, the method of urea application and to the amount of lime applied under upland and waterlogged soil conditions. lOO g. of air dried alluvial soil in an Erlenmeyer flask was added with 15 or 60 mg N as urea, from O to 180 mg of calcium oxide and was incubated at 30℃ for three weeks as shown in Fig. 1. Ammonia free air was passed through the flask and the ammonia volatilised was collected by standard acid. The results are shown in Table 1 and 2. The loss amounted to 2.2〜0.0 mg N per 100 g. air dry soil under the upland soil condition, whereas under the waterlogged it increased to 5.3〜0.1mg. For the increase by waterlogging is primarily responsible the higher soil pH on waterlogging as compared to upland. In general, the loss increased as the amount of nitrogen and lime applied increased respectively and was more pronounced in the surface application of urea than in the total layer application. The loss appears to be primarily dependent on the concentration of the ammoniacal nitrogen transformed from urea and soil pH. In view of the recent increase of the use of urea fertiliser in Japan, discussion on its practcial application particularly as top dressing was made on the basis of the laboratory results obtained. Even in extreme cases, it is supposed that only a few percents of the applied nitrogen will be lost by direct volatilisation provided that the soil is not too alkaline.

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When rice plant is low or medium in nitrogen concentration at about 30 days before earing, the top dressing so called "Hogoe" is effective on grain yield. If rice plant is high in nitrogen, however, this top dressing increases susceptibility of plant to pathogens and the fear of damage by unfavorable weather. For this reason, to examine the nitrogen status of plant before this top dressing seems to be very useful. In this experiment, based on previous results that asparagine appeared only when rice plant was high in nitrogen, the author found relationship between the effectiveness "Hogoe" and the nitrogen status of plant assessed by asparagine test. The utilisation of asparagine test as a guide for "Hogoe" should be very hopeful.

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A reconnaissance survey was made by the authors on causes of the unproductivities of the paddy fields at Sasu Village in Tsushima. A considerable number of farmers at that village are of opinion that the infertility of soils due to the contamination of poisons from the mines which are situated at the upper reaches of the Sasu River. The main minerals of the mines are blends, galena and iron pyrite. Of soils, plants (barley) and waters from the fields, analyses were made as to their contents of zinc and lead. The results were obtained as follows : 1. Of the fields, affected most profoundly and left as fallow lands after harvesting rice crops, the soils had such a total content of zinc as much as 2,000 ppm. And about fourty percent of this zinc was in available form. It may be considered that the zinc in the soils has poising effects upon vegetation, when it attains its amount as much as this amount in available form. 2. The more the soil contained available zinc, the more the plants contained zinc and were suffered from detrimental effects on their growth. 3. Lead was contained in such quantities as it was likely injurious upon plant growth. 4. It was estimated 7.2kg of zinc and 0.1 kg of lead were discharged in to the river per day from an active mine at Sasu Section. 5. It was suggested that the poor paddy fields had been probably developed owing to the following facts : a) deposition of mine refuse on the field by the floods, b) absorption of zinc in the irrigated water by the soil, c) transportation of slime particles, suspended in the irrigation water, d) ascending of ground water by capillary action in the drought season, e) dressing of the compost made of plant materials grown on the affected lands.

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We shall report the results of an estimation of free iron oxides in soils by improved JEFFRIES's magnesium ribbon-potassium oxalate method, comparing with TRUOG's sodium sulfide-oxalic acid method. Improved magnesium ribbon reduction method is as follows; Procedure : Place 2 to 5 g of air dried fine soil (<2mm) into a 300 ml beaker, add 30 ml of 10% H_2O_2 and stir thoroughly. Then, place it on a boiling water bath to digest organic matter as soon as possible, and evaporate to dryness. Repeat it until practically all organic matter would be decomposed. Usually, these two treatments shall be enough. Add 40ml of potassium oxalate solution containing 4.15g potassium oxalate and 1Oml of oxalic acid soluon containing 0.95 g oxalic acid. Stir thoroughly until all of the dried. organic matter-free soil would be loosened from the bottom of the beaker. Then, place it on a boiling water bath, and heat it to about 85〜90℃. Stir violently with a glass rod coiled around on the end with a magnesium ribbon (1O cm length weighing about 0.2g), keeping at the same temperature for 3〜5 minutes or until clay and sand would become white or gray. Take down the beaker and take out the glass rod. Let it stand for a moment. Then, filtrate the supernatant by means of the decantation method. Add potassium oxalate solution and oxalic acid solution to the residue, heat and reduce it with the magnesium ribbon in the same manner. Let it stand for a moment again and filtrate the supernatant by means of the decantation method. Wash free from iron with 30 ml portion of acidified 0.5% NaCl solution adjusted to pH about 3.5 with N-HCl. Usually, four times washings shall be enough. The magnesium ribbon shall be washed with some portion of dilute HCl and the washing shall be put into the filtrate and made up them to a definite volume. This solution, we can reserve for the determination of free iron oxides. Transfer a definite volume of this solution to a small evaporating-dish. Oxalate contained in solution should be decomposed. The residue shall be converted to chloride or sulfate. And then, determine the ferric oxide by titration with standard 0.01 N mercurous nitrate. The procedure is as follows; A solution of HgNO_3,approximately 0.01 N, shall be prepared using 5% HNO_3. After keeping for a week, the solution would be standardized by titration against a standard solution of FeNH_4(SO_4)_2 or Fe_2(SO_4)_3. As a change in normality would be insignificant even after several months, the initial standardization would be sufficed. The iron should be in the ferric state and should be neither more than 10 mg with respeet to Fe_2O_3 nor less than 1 mg. The solution (at room temperature) is diluted to a volume of about 100 ml and added 5 ml of 40% NH_4SCN solution. Then, titrate the solution with the HgNO_3. It should be noted that the solutioh should be stirred vigorously and the HgNO_3 is added dropwise and slowly near the endpoint, in which the red color would be absent. The solution becomes turbid when the endpoint is overrun. Summary : 1) The procedure is simple, and adaptable to routine laboratory work, and suitable for the determination of many samples. 2) As the MnO_2 added to soil has been reduced and fully recovered by this method, the method seems to be suitable for determining some kinds of forms of manganese oxides in soils. 3) Free iron oxides in soils determined by this method give somewhat lower value than that of TRUOG's nascent hydrogen sulfide method, and higher value than TAMM's method. 4) 4 to 6% as Fe_2O_3 was removed by this method and 17% by TRUOG's method from the fine particles (0.2mm) of micaceous hematite containing 54.7% of iron as Fe_2O_3.

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The experimental work reported in this paper deals with the problem of the influence of iron sulfide, which has been formed in polder soils under an anaerobic condition on the change of reaction and soluble salt after drainage. The results obtained may be summarized as follows : (1) In most of soils, the original pH values of waterlogged samples become extremely acid after the incubation at 30℃ under the condition of the moisture content of field capacity for several weeks. Total and water-soluble sulfates are increased greatly in the incubated samples. (2) There appears to be definite relation between the soil color and the content of FeS in waterlogged samples. (3) The content of FeS_2 lies between 0.24% and 0.98% in the water-logged samples but it decreases greatly after incubation. It will be seen from table 2 that the total amount of SO_3 calculated from remained FeS and decreased FeS_2 agrees fair well with that calculated from increased watersoluble sulfates. It is shown that FeS_2 plays an important role in the change of reaction of halogenetic polder soils after drainage.

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