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



three-fourths of a pound to 6 pounds of acid phosphate per 4 bushels of 

 manure. The larvicidal results were very irregular , but it is evident 

 that 1 pound of cyanamid is not effective in open piles. 



Some results of the effect of larger applications of mixtures of 

 cyanamid and acid phosphate in open-pile experiments at Baton 

 Rouge are recorded in Table 6, Nos. 3 and 4. 



In series No. 3 the mixture contained 3 pounds of cyanamid and 12 

 pounds of acid phosphate per 8 bushels of manure. From the two j 

 control piles 263 and 62 flies emerged, but using the average of these | 

 two figures, a 57 per cent and a 90 per cent larvicidal action was 

 apparently obtained. Attention is called to the fact that from cage 

 3A, 70 flies emerged, a count higher than the lower control. On i 

 account of the uneven infestation of the manure used in these tests 

 the percentages have little value. The number of bacteria in 3B, 

 where a 90 per cent larvicidal action was obtained, was reduced 50 

 per cent by the treatment. The total nitrogen of the manure appar- 

 ently was increased by the treatment, as was the water-soluble and * i 

 ammonia nitrogen. The greatest increase was in the amid nitro- 

 gen. There was apparently a slight increase in the alkalinity of the 

 water extracts. Nitrates were detected in all of these samples. 



In No. 4, Table 6, 4 and 5 pounds of cyanamid were mixed with 

 equal amounts of acid phosphate. With both mixtures the larvi- 

 cidal results were highly satisfactory. 97 and 99 per cent of the larvae 

 being destroyed. No reduction in the number of bacteria in the 

 treated samples was found. An increased percentage of total and 

 amid nitrogen due to the nitrogen of the cyanamid was obtained in all 

 of the 4 samples, while 3 of the 4 samples showed an increase in the 

 water-soluble nitrogen. Less ammonia nitrogen was found in 3 of 

 the 4 samples than in the controls. The alkalinity slightly increased 

 in all cases. All the samples showed the presence of nitrates by the 

 diphenylamin method, the color reactions being stronger in the 

 treated than in the untreated samples. 



Many temperature readings of the manure treated with mixtures 

 of cyanamid and acid phosphate were taken. In practically all 

 instances the results of the readings in the case of the treated samples 

 were the same as in the case of the controls. This is in line with the 

 bacterial counts and indicates that no marked action on the bacterial 

 flora had taken place. 



It is probable that the cyanamid is the principal toxic constituent 

 of the various mixtures, and the cyanamid which is soluble in water 

 is undoubtedly more toxic than its polymer dioyandiamid. 



Kionka (5) has reported experiments showing that 0.1 gram of pure 

 cyanamid is a fatal dose for dogs, when given subcutaneouslv. while 



