Japanese Journal of Soil Science and Plant Nutrition

As a trial to hasten the fermentation of artificial farm-yard manure, two sets of heaps were made, the one being stacked with wheat straw alone and the other with the mixture of wheat and rice straw (1 : 1). To every heap of each set Ca-cyanamide was added at the rate of 2% in series (A) and 3% in (B), otherwise all the heaps received the same treatment. The quantity of the straw per heap was 375 Kg in air dry state. To protect the heaps from wind and rain, this trial was carried out in a shed provided with wall and roof. The results were briefly as follows : [table] Note : The temperature of the central part in each heap was observed daily at 10 o'clock. The atmospheric temperature was also recorded simultaneously, the mean during twenty days from the start (from August, 29 to September, 18,1935) being 24.9℃. Thus we have observed a remarkable difference in intensity of the fermentation according as either the rice straw was mixed or not. This good effect of the rice straw is attributed to its physical nature by which the aeration through the heap was properly regulated : As well known, the rice straw gets quickly in its wet state a flexible and soft texture. Since the wheat straw, on the contrary, is of coarse texture, when it is used alone as the raw material the aeration should necessarily take place excessively, on account of the usual insufficiency of consolidation of heap. The excessive aeration will lead to the restricted heat accumulation in heap. It is especially so when the atmospheric temperature is low and the experiment is done on the small scale as ours. Under these conditions, therefore, it is impossible to expect for the heap to attain a high temperature. Such an objection, however, which is thus caused primarily by the insufficient consolidation, may easily be put aside by the use of the rice straw, resulting in a moderate aeration that will be accompanied by the accumulation of requisite heat. Finally, it is suggested that weedings, grass cuttings, etc. may also be used as well for hastening the fermentation by mixing either with wheat straw or the like.

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Further experiments on the respiration were made, in which consumptions of oxygen by three species of root nodule bacteria and their respiratory quotients in a buffer solution were concerned under an atmosphere containing different quantities of oxygen, and also two species 5 of the bacteria in the yeast water mannitol solution under that containing 20 per cent oxygen, varying percentages of CO_2,and sufficient nitrogen to make one atmosphere. Oxygen consumed by Rh. trifolii under PO_2 lower than that of ordinary air (20 per cent) was repressed, whereas that by Rh. meliloti as well as Rh. lupini was not. With regard to respiratory quotients, data obtained with Rh. trifolii was larger than with the others, but must be below carbohydrate level under consideration of no aerobie glycolysis. It was suggestible that an atmosphere containing quantities of CO_2 greater than 0.05 per cent would initiate the respiration process of Rh. trifolii on the whole.

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The writer has previously pointed out the fact that the transformation of some dicyanodiamide from cyanamide is inevitable when the commercial cyanamide is mixed with less than 500 times of ordinary soils. As a fertilizer for common dry field crops, it, therefore, is not desirable to submit the commercial cyanamide to the pre-treatment, such as mixing with soils, composts, etc. On the contrary, there is no need of nitrification in soil in paddy rice-culture and as the paddy rice has a great resistance to the direct harmful action of dicianodiamide, the transformation of dicyanodiamide, in some degree, is allowable in paddy-rice culture, though more loss of nitrogen through drainage would be resulted because of the difficulty of absorbing dicyanodiamide by the soils. The present experiments have been carried out to examine the result of pre-treatment of commercial cyanamide for top dressing purpose when it could not be applied before the rice-transplanting, due to some special cause such as bad weather etc. The result of experiments follows : 1. When the commercial cyanamide is mixed with less than 90 times of soils or composts, 2/3-4/5 of cyanamide disappears within 2 weeks, while more than 1/3 of cyanamide is polymerized into dicyanodiamide (tables 1 and 2). The above pre-treated mixtures have no noticeable harmful action upon the crops whether applied before rice-transplanting or top-dressed afterward. An yield-decrease in the fiield however is experienced, when the normal dose of nitrogen is applied (tables 3 and 4). This is due to the fact that most of dicyanodiamide is washed out in natural drainage, resulting the shortage of avairable nitrogen. 2. When the rati of commercial cyanamide : soil or compost is in the range of 1 : 12 to 1 : 50,the pH value of the pretreated mixture is more than 10. With the addition of putrefied rice bran or the like acidic materials to the mixture, the pH value decreases nearer to 9.6,which is the optimum hydrogen-ion concentration for polymerization of cyanamide into dicyanodiamide, thus largely increasting the formation of dicyanodiamide (tables 5-7). By tae same reason, in the soils having high buffer capacity for lime, more dicyanodiamide is formed by lowering pH value of the mixture, nearer to 9.6,than the soils having low buffer capacity (tables 8 and 9). This fact is contrary to the case of directly applying the commercial cyanamide to the farm soil. In the latter case the quantity of soil to commercial cianamide is exceedingly large and the pH of the mixture becomes less than 9.6,if the fertilizer is properly distributed. The soils having high buffer capacity, toe pH of soil solution would be far below 9.6-some times below 7.0-and the pylymerization velocity of cyanamide in such soils would be very slow

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1. The average composition of 48 kinds of fowl excrements which were collected from various districts in Kagawa prefecture is as follows : [table] 2. As seen in the table above mentioned the percentage of water soluble phosphoric acid for total phosphoric acid are respectively 53 and 16.8. 3. Fowl excrement is at once quick and slow as nitrogenous manure, consequently special attention must be taken for its manuring and appreciation.

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