CYANAMID — manufacture:, CHEMISTRY AND USEJS 79 



Cyanamid and other fertilizers, toxicity is a question of con- 

 centration, although the specific toxicity of pure dicyandiamide 

 is considerably larger than that of impure dicyandiamide. 



Some tests were also made with rice transplanted to field 

 plots (0.83 qm.) manured alike with superphosphate, potassium 

 carbonate and nitrogen compounds at the rate of 90 pounds 

 per acre each of phosphoric anhydride, potash and nitrogen 

 (except control). The nitrogenous substances were am- 

 monium sulphate containing 21.2 per cent, nitrogen, lime-nitro- 

 gen with 12.47 P^i" cent, nitrogen, and dicyandiamide with 46.7 

 per cent, nitrogen. They were applied at different periods be- 

 fore the transplanting of the rice clumps. The total weight 

 in grams of the plants obtained in the air dried state were : 



Fertilized days before planting 



Fertilized with o 7 14 21 28 35 



No manure 229 — — — — — 



No nitrogen 436 — — — — — 



Ammonium sulphate • • 764 — — — — — 



Lime-nitrogen 614 767 786 807 788 744 



Dicyandiamide 507 575 572 670 652 609 



The yield of clean grain was as follows : 



Fertilized days before planting 



Fertilized with 7 14 21 28 35 



No manure 75 — — — — — 



No nitrogen 149 — — — — — 



Ammonium sulphate • • 266 — — — — — 



Ivime-nitrogen 197 259 260 258 280 257 



Dicyandiamide 183 208 209 238 244 239 



This experiment shows a somewhat lower result with lime- 

 nitrogen than with ammonium sulphate applied at the time of 

 planting, but a somewhat larger yield when the lime-nitrogen is 

 applied 7 days before planting. The dicyandiamide is more 

 effective when applied two or three weeks before planting than 

 when applied at the planting, but it is never as effective as 

 the ammonium sulphate, being at the best about 89 per cent, 

 as effective in producing grain. In the cultivation of rice in 

 America the maximum utilizable application of nitrogen does 



