Abstract
One of the main cause for "Akiochi" is owing to the absorptive condition of nitrogen in the several stage of rice growth. Namely, normal rice plants usualy absorb nitrogen slowly and continuously through life. But "Akiochi" rice are not so. The organic manure such as fish meals and oil cakes are excellent for preventation of "Akiochi". But these manures cannot be produced so much and cheaply. Accordingly, there is necessity of inorganic nitrogen fertilizer with the characteristics absorbed slowly by rice. This is the purpose of this study. The result summarized as follows : 1. Massed calcium cyanamide are made from calcium cyanamide by adding Na-Silicate aq. and this fertilizer contains 16% N. 2. Ammonification of massed calcium cyanamide in the paddy soil is rather slow and continious than calcium cyanamide. 3. Massed calcium cyanamide prevented the "Akiochi", and obtained the higher yields than calcium cyanamide or ammonium sulphate. 4. Massed calcium cyanamide did not appear to injure the rice, even if transplanted immediately after dressing. 5. Roots colour of rice which grew up with the massed calcium cyanamide were more reddish brown and healthy than others. 6. Massed calcium cyanamide existed in the soil still at harvest time, and contained 1.7% N.
