78 CYANAMID — MANUI^ACTURE:, CHEMISTRY AND USES 



R. Inouye^ made pot tests with rape and barley, fertilizing 

 with a dicyandiamide made by himself from lime-nitrogen, and 

 and analyzing 46.7 per cent, nitrogen. The rate of fertiliza- 

 tion was equivalent to 2,400 pounds superphosphate per acre, 

 1,200 pounds potassium carbonate and the amounts of nitrogen 

 shown in the table below, which gives also the yield obtained : 



The dicyandiamide in the fourth pot was applied as a top- 

 dressing. Although the fertilization was very heavy there is 

 no doubt that the results are very good when 80 pounds of 

 nitrogen from impure dicyandiamide is used with ammonium 

 sulphate, although 240 pounds of nitrogen from dicyandiamide 

 alone is little better than no fertilizer. This is clearly an ex- 

 cessive amount of dicyandiamide. 



K. Aso^ made some toxicity tests with a dicyandiamide 

 made by himself from lime-nitrogen, and analyzing 59.88 per 

 cent, nitrogen. Buckwheat and oat plants were grown to a 

 height of about 10 cm. in ordinary soil and were then trans- 

 ferred to flasks containing solutions of different concentrations 

 of dicyandiamide. When the solutions contained less than 

 o.oi per cent, of nitrogen from dicyandiamide the plants con- 

 tinued growing normally and developed better than in the 

 control flasks. When larger concentrations were used the 

 plants showed the characteristic effects of dicyandiamide 

 poisoning; that is, for increasing doses, first, appearance of a 

 brown color on the tips of the leaves, then drying of the tips, 

 although usually followed by recovery and increased growth; 

 finally, with very large concentrations, curling and drying up 

 of the leaves and destruction of the plant. Here, as with 



1 Jour. Coll. Agr. Imp. Univ. Tokyo, Vol. I, No. 2, 1909, p. 193. 



2 Jour. Coll. Agr. Imp. Uuiv. Tokyo, Vol. i, No. 2, 1909, p. 211. 



