Journal of Agricultural Research 



Vol. VI. No. I 



AzoTOBACTER. — One month after treatment with carbon bisulphid, 

 qualitative tests were made. The Azotobacter organisms were found in 

 all soils. The brown film of Azotobacter from the treated soils was not 

 so profuse as that from the original soil. 



ALiGM. — In order to estimate the number of algae, dilution tests were 

 made. These cultures were incubated for 30 days. The smaller forms 

 were found in great numbers in all of the soils. 



The important facts in these data are (i) that the volatile antiseptic 

 fails to remove these larger soil organisms and (2) that the smaller forms 

 of bacteria are only temporarily reduced. The decrease in numbers is 

 soon followed by a period of excessive growth. 



ACTIVITY OF ORGANISMS 



A rapid multiplication of bacteria should naturally be followed by a 

 parallel increase in decomposition products. Accordingly samples for 

 analysis were drawn from the jars used in the previous experiment. 

 The results of these periodic analyses are presented in Table II. 



Table II. — Effect of carbon bisulphid on ammonia and nitrate content of soil 



Time. 



Nitrogen per loo jjm. of dry soil. 



Ammonia. 



Control. 



2 per cent 

 of carbon 

 bisulphid. 



2 per cent 

 of carbon 

 bisulphid 

 evapo- 

 rated. 



2 per cent 

 of carbon 

 bisulphid 

 evapo- 

 rated +5 

 per cent of 

 soil from 

 control. 



Control. 



2 per cent 

 of carbon 

 bisulphid. 



2 per cent 

 of carbon 

 bisulphid 

 evapo- 

 rated. 



2 per cent 

 of carbon 

 bisulphid 



evapo- 

 rated+s 

 per cent of 

 soil from 



control. 



Days. 

 At beginning 



30 



45 



60 



75 



90 



Mgm. 



60 

 68 



38 

 59 

 85 

 94 



Mgm. 

 I. 60 



5-27 

 8.40 



5-43 

 5.60 

 4. 06 



Mgm. 

 I. 60 



4. 06 



Mgm. 



1. 60 

 4.71 

 4.90 

 2.31 



2. 10 

 2. 24 



Mgm,. 

 2.66 



4. 00 



Mgm. 

 2.66 

 2. 50 

 2. 70 

 2.81 

 2. 40 

 5.00 



Mgm. 

 2.66 

 2. 00 

 2.50 

 2.50 

 2. 60 

 3-32 



Mgm. 



2.66 



55 

 66 



5° 



5. 00 

 6.66 



In the soils treated with carbon bisulphid there is a very decided accumu- 

 lation of ammonia nitrogen. If the figures of Table I are compared 

 with those of Table II, ammonia production, it will be seen that an 

 increase in the number of bacteria within a certain range results in a 

 gain in ammonia. After 30 days the amount of ammonia nitrogen in 

 the treated soils averaged more than three times that in the original soil. 

 After 60 days the ammonia content in the carbon bisulphid and car- 

 bon bisulphid evaporated soil was about double that of the control, 

 while in the carbon bisulphid evaporated plus 5 per cent fresh soil it was 



