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



ton is $51.45, or 2.6 cents per pound in ton lots. Cyanamid is at 

 present handled only in large amounts and by manufacturers of 

 mixed fertilizers. It requires only the demand to make it available 

 in all parts of the country. During the fall of 1 91 5, several lots of acid 

 phosphate were purchased, and the average price, when purchased in 

 hundred-pound lots, was 1 cent per pound. It was quoted at $14 per 

 ton January 1, 1916. Four pounds of the calcium cyanamid and 4 

 pounds of acid phosphate, as seen in Table 6, series 4, showed an 

 effective larvicidal action. The cost of this mixture was 14^ cents per 

 8 bushels of manure, or 1.8 cents per bushel. In Table 6, No. 4, 

 the results also show that a mixture composed of 3 pounds of calcium 

 cyanamid and 6 pounds of kainit gave an effective larvicidal action. 

 The cost of the treatment in this case was 1 J cents per bushel. In the 

 experiments in cages and in boxes mixtures containing 1 pound of the 

 cyanamid and 2 pounds of acid phosphate per 8 bushels have given 

 satisfactory results. The cost in this case was one-half cent per 

 bushel. 



From these figures it appears that the fertilizer mixtures applied 

 in sufficient amounts to act as effective larvicides on open piles are 

 more expensive than borax or powdered hellebore. However, in the 

 former treatment the fertilizing value of the manure is greatly 

 increased, and when considered from this point of view the actual 

 larvicidal cost of the fertilizer mixtures is materially lessened. 



THE AMOUNTS OF MANURE TREATED WITH FERTILIZER MIXTURES TO APPLY TO THE 



SOIL. 



One hundred and fifty pounds of calcium cyanamid per acre is 

 stated by Pranke (6) to be the most economical amount to apply to 

 the soil at one time. When manure is treated in boxes or pits at 

 the rate of 1 pound of calcium cyanamid and 2 pounds of acid phos- 

 phate per 8 bushels (10 cubic feet) of manure, taking the weight of 8 

 bushels of fresh manure at 120 pounds, it is calculated that 16§ 

 pounds of calcium cyanamid and 33 pounds of acid phosphate will 

 be present per ton of fresh manure. If it is desired, kahiit may be 

 used in place of a part of the acid phosphate in the mixture. Manure 

 treated in this manner and applied to the soil at the rate of 9 tons 

 per acre will furnish 150 pounds of calcium cyanamid, which is 

 mentioned above as being the most economical application of the 

 cyanamid. The application of more than 9 tons per acre would be 

 uneconomical. 



When piles of manure are treated with a mixture containing 4 

 pounds of calcium cyanamid and 4 pounds of acid phosphate, these 

 two substances are added to the manure at the rate of 65 pounds per 

 ton. As above, the weight of fresh manure is taken at 15 pounds 

 per bushel. The manure treated with this mixture should be applied 

 to the soil at the rate of only 2\ tons per acre. 



