14 BULLETIN 408, U. S. DEPARTMENT OF AGRICULTURE. 



COMMERCIAL MIXED FERTILIZERS CONTAINING CALCILM CYANAMID. 



Calcium cyanamid is frequently used to furnish the nitrogen of 

 mixed fertilizers, either in whole or in part. Such fertilizers usually 

 do not contain any calcium cyanamid as such, since the cyanamid 

 has been decomposed into urea, ammonia, etc. The percentage of 

 calcium cyanamid used in commercial mixed fertilizers varies with 

 each brand. The commercial f ertilizer which was employed in this 

 test contained 12^ per cent phosphoric acid, 2| per cent ammonia, 

 and 2 J per cent potash. 



One-third of a bushel of manure was treated with 1 pound of the 

 mixed fertilizer in a box covered with netting. The sample was 

 then well moistened. Only 2 flies emerged from the box which was 

 treated with the mixed fertilizer, while 909 flies emerged from the 

 control box. The application of the mixed fertilizer in this experi- 

 ment was a very heavy one, and as but one experiment was carried 

 out, and that one on a small scale, no conclusion can be drawn. 

 As manufacturers employ varying amounts of cyanamid in their mix- 

 tures it is impossible to use commercial mixtures as a larvicide with 

 any assurance of obtaining satisfactory results without first testing 

 the mixture in question and determining the amount necessary to 

 apply to the manure to destroy the maggots. 



THE AMOUNTS OF FERTILIZER MLXTURES TO APPLY TO PITS AND PILES OF MANURE TO 



KILL FLY LARVAE. 



From all of the cage tests and the box experiments (Table 5, No. 

 3) the indications are that mixtures containing 1 pound of calcium 

 cyanamid and 2 to 4 pounds of acid phosphate will destroy a high 

 percentage of the maggots of the house fly present in 8 bushels of 

 manure, when the manure is placed in such receptacles. In these 

 cases the surface treated was much smaller than in an open pile con- 

 taining the same amount of manure, and as the surface was prac- 

 tically level the mixture could be applied effectively and forced into 

 the manure by sprinkhng with water. It seems likely that the mix- 

 tures will act effectively when applied to manure in pits where 

 approximately the same conditions exist as in the box or cage tests; 

 that is, where there is only one surface to be treated. One pound 

 of cyanamid in mixtures was used successfully in a box having a sur- 

 face exposure of 5 square feet and in cages with a surface of 4 square 

 feet. It is therefore suggested that mixtures containing 1 pound of 

 cyanamid and 2 to 4 pounds of acid phosphate be applied to boxes 

 or pits at the above rate per 4 square feet of surface exposure. The 

 ideal way of storing manure is in a water-tight pit. If this is not 

 available, the manure may be thrown into a large box and then 

 effectively treated with the cyanamid mixture at the above rate. 



In the treatment of piles of manure it is evident from the results in 

 Table 6, series 4, that 4 pounds of calcium cyanamid applied in mix- 



