DESTRUCTION OF FLY LARVAE IN HORSE MANURE, 1915. 15 



tures with either acid phosphate or kainit per 8 bushels of manure 

 acts as an effective larvicide . To be sure of retaining all of the nitrogen 

 and ammonia which ordinarily is lost from a pile of manure, a higher 

 ratio of acid phosphate to calcium cyanamid than was used in these 

 tests should be employed. The chemical analyses of No. 4, Table 6, 

 show no changes from the control samples, but the results of Table 

 5, No. 2, show the advantage of using a large proportion of acid 

 phosphate. 



Kainit may be employed in the mixtures together with the cyan- 

 amid and acid phosphate. Thus potash, as well as lime, nitrogen, 

 and phosphoric acid, will be added to the manure. The substitution 

 of kainit for part of the acid phosphate makes no apparent difference 

 in the larvicidal action of the mixture. It is important to apply 

 in the mixture one-half pound of calcium cyanamid per bushel of 

 manure. The manure should be thoroughly sprinkled with water 

 after each application of the cyanamid mixture. It is probable that 

 gypsum may be substituted in whole or in part for the acid phosphate. 



THE VALUE OF USING CALCIUM CYANAMID, ACID PHOSPHATE, AND KAINIT ON MANURE. 



It is likely that calcium cyanamid, which contains lime in amounts 

 equivalent to 70 parts of Ca(OH) 2 per 100, if used alone on fresh 

 manure in any considerable amount, will expel some of the nitrogen 

 and ammonia present in the manure. Acid phosphate was used in 

 the mixtures with the cyanamid, in part to neutralize the lime, and 

 also to hold the nitrogen and ammonia which might be expelled by 

 the lime of the cyanamid, as well as to retain the nitrogen and, ammo- 

 nia lost during ordinary fermentation processes. During the decom- 

 position of calcium cyanamid in the soil the lime is gradually precipi- 

 tated as carbonate, and this same process undoubtedly takes place in 

 the manure. Acid phosphate, kainit, and gypsum are quite exten- 

 sively recommended for the purpose of preserving manure. Commer- 

 cial acid phosphate contains about 14 per cent of available phosphoric 

 acid; kainit contains approximately 12.5 per cent of potash, and 

 cyanamid contains 20 to 22 per cent of ammonia. It is accordingly 

 evident that when the above mixture is applied to manure the three 

 essential fertilizing elements are added in considerable amounts, and 

 if acid phosphate is used in a ratio of 6 or 8 to 1 no loss of ammonia 

 will result, but the nitrogen and ammonia which escape during the 

 normal fermentation of manure will be retained. 



THE COST OF EFFECTIVE FERTILIZER MIXTURES. 



Under normal conditions kainit sells for $12 to $14 per ton, making 

 the cost about two-thirds of a cent a pound. Kainit is not avail- 

 able at the present time. Calcium cyanamid was quoted January 1, 

 1916, at $2.45 per unit of ammonia. Calculating the average per- 

 centage of ammonia present in cyanamid at 21 per cent, the cost per 



