G. A. CowiR 



119 



number of bacteria capable of development on gelatine plates. None of 

 the dressings, however, seems to have exerted any marked effect on 

 these immbers. Some stimulation of the bacteria in the initial period 

 may have been caused by the cyananiide in series 1 and 3, but no 

 marked depression of the numbers was produced by dicyanodiamide. 

 In series 1, where the largest dressing was used, the numbers with the 

 pure dicyanodiamide show practically no greater variation than the 

 natural fluctuation of the control: 



Bacteria. Millions per gram of fresh soil 



Similar results were obtained in the other series. 



Effect of Dicyanodiamide on the A mmonification of Dried Blood. 



The influence of dicj'anodiamide on the ammonifying organisms 

 was studied by determining the rate of ammonification of dried blood. 

 The results were: 



Control 

 Dried blood 

 Dried blood + ) 



dicyanodiamide j 

 Dicyanodiamide "| 

 alone J 



Added 50 rags, dried blood N per kilo soil = 60 parts of N per million dry soil. 

 15 mgs. dicyanodiamide N per kilo soil. 



Total N as Nitrate + NH3 

 per million dry soil 



Bacteria. Millions per gram 

 of fresh soil 



Control 



Dried blood 



Dried blood + ) 



dicyanodiamide J 

 Dicyanodiamide "| 



alone J 



At After After After After 



start 7 days 21 days 42 days 94 days 



11-4 16-2 20-1 21-4 25-8 



— 21-5 300 38-5 39-9 



At After After After After 



start 7 day.s 21 days 42 days 94 days 



120 no 141 8-3 200 



— 15-7 19-4 24-6 23-0 



19-5 

 130 



29-5 



11-7 



:J5-2 



18-5 



31-5 

 150 



10-4 

 110 



15-2 

 8-3 



240 

 13-7 



19-2 

 140 



