Abstract:For understanding correlations between the high yield of soybean and the biochemical characteristics of the soils, field experiments were carried out with different fertilizer treatments. In one series of the plots both organic manure and chemical fertilizers were applied, while in the second series only organic manure was used. A third series without fertilizer treatment was taken as control. The biochemical activities of the soil were studied at different growing stages of soybean. Results of present experiments showed that there are definite correlations between the yield of soybean and the biochemical activities of the soil, including enzyme activities, respiration and rate of cellulose decomposition. Good correlations are also found between the yield of soybean and amount of free amino acids present in the soil. The origin of the enzyme activities and the active substances in the soil also show an intimate relationship with the soil microflora. Soil particles possess great absorptive power for the enzymes, other active substances, and soil microorganisms without any inhibition of their activities.

Abstract:For the extraction of reducing compounds from paddy soils, a 0.1M Al₂(SO₄)₃ solution of pH 2.5 was proposed. It was found that the extracting power of this solution was strongest among the eight tested solutions, and owing to the strong buffeting capacity of the Al₂(SO₄)₃ solution, the pH values of the equilibrium solutions for different types of soils fluctuated within only a narrow range (2.65-3.15). A soilaolutian ratio of 1:20 and stirring for 5 minutes were sufficient. The extracting solution possesses the further advantage that various reducing compounds may be determined directly in separate aliquots without preliminary separation, which is necessary for determining the easily oxidizable compounds when in contact with the air. The reducing compounds were determined as manganous Mn, ferrous iron, active organic reducing compounds oxidizable by titration with permanganate at room temperature and non-active organic reducing compounds oxidizable by heating with dichromate at 90-95℃ for 20 minutes. Since the amount of extracted active organic reducing compounds is ra.her constant between pH 2.5 and 6.5 and the extracted iron is dependent on the pH value of the equilibrium solution, it is considered that the active organic reducing compounds represented a definite group of easily extracted compounds and is quite reversible with respect to oxidation-reduction reactions, whereas a large part of the ferrous compounds may exist in forms of hydroxide, sulfide and bicarbonate.

Abstract:The materials of present report were collected from reconnaissance soil survey of Kwangtung and Kwangsi provinces in 1958-1960. Soils investigated include yellow earths, red earths and lateritic soils. They are developed under natural vegetations of tropic monsoon forest (secondary), subtropic evergreen broadleaf forest, conifer and broadleaf mixed forest, subalpine dwarfing and bamboo ferests, confer forests of Cunninghamia lanceolata and Pinus massoniana, and grass land. A Few samples of rice paddy soil were also studied far comparison. Laboratory investigations involved the determination of chemical composition of forest litters, fraction of soil humus (after Turin and hononova), and analysis of soil exchangeable bases, active iron and alumina, etc.

Abstract:Одним из основных типов рисовых почв в северных субтропиках является бей-му,которая широко распространяется в пространстве к югу от р.

Abstract:To soils of pot, culture experiment, having top-dressed with manures and ammonium sulphate,the rate of liberation of ammonia during hydrolysis in different alkaline mediums was measured by distillation with MgO, CaO and 0.5 N NaOH, and by replacement of N NaOH solution ae room temperature (Conway's diffusion method). Soil samples were taken at intervals of 1,5,10,15,20 and 30 days after fertilization. Variations of nitrogen content in plant leaves at different stage of growth were also determined. Through mathematical analysis from the data involving rate and capacity of the liberation of ammonia in alkaline mediums, the writer endeavors to predict nitrogen supplying status of paddy soils through out the growing season of rice.Except soils recieved stable manures the amount of nitrogen from MgO distillation gives correlation with the V₀ initial rate of liberation of ammonia of N NaOH diffusion method and distillation methods. Figures obtained in MgO distillation are higher than the ammonical nitrogen in soils. The increment is induced by the partial hydrolysis of amides.

Abstract:Вегетационные и полевые опыты проведены на аллювиальных луговых почвахза городом Шзньян в целях выяснения зависимости урожайности и состава пшеницыот доз азотных,фосфорных и калийных удобрений при их разных отношениях.

Abstract:A spectrographic procedure using copper electrodes, a medium dispersion quartz spectrograph (Q 24), and an activated a.c. arc as light source for the determination of micro-quantities of calcium, stronrtium and barium in water and soil extracts is described. 300 mg sodium chloride are added to 25 ml of the solution to be determined, as spectrographic buffer; then 1 ml 0.6 N HCl, and finally 1 mg zinc (as zinc sulfate) is added as internal standard. 0.025 ml of this solution is transferred to the upper and lower electrodes and evaporated to dryness at 55-60℃. The electrodes are excited at 6 amperes for 30 seconds.The analytical line pairs used are: Sr4215.52/Zn4722.16, Ba4554.04/Zn4722.16, Ca4425.44/Zn4722.16.Samples with as low a concentration as 0.1 γ-ml may be determined with a precision of better than ±5% relative deviation, using fixed working curves. The results of the spectrographic determination of calcium are in good agreement with results obtained using a chemical method. Neglecting results of very low calcium contents, the differences between results of the spectrographic method and the chemical method are usually less than ±10%. The influences of calcium and magnesium concentration upon the line intensities of barium and strontium, and the method of its elimination; the influence of solution acidity upon line intensities and the reproducibility of results are also discussed. It is found that the buffer action of sodium chloride is quite effective.

Abstract:In the original procedure of J. L. Smith's method for determining potassium in soils, solid ammonium chloride is pulverized with soil sample and then mixed with calcium carbonate, The writers recommend to mix soil and calcium carbonate in advance, and the mixture is moistened with 15% NH₄Cl solution. Experimental results also show that the fusion can be done directly in a muffle of 700℃ without significant volatile of ammonium chloride.Potassium can be determined in a portion of water extract in flame photometer without the previous removal of Ca⁺⁺ ion. Results show good agreement with the original method.

Abstract:"Gauze No. 1" medium was used as a culture medium for the isolation of soil actinomycetes with the addition of 100 ppm K₂Cr₂O₇. The modified medium gives larger colony numbers and more kinds of species with distinguishable characteristics in comparison with the original method, but the growth of bacteria and fungi have been largely inhibited. Using this medium, the same species may 'be grouped into species group, and it is possible to identify the names of species group directly on the plate.