72 



each tumbler was kept covered in a dark closet. The 

 soil used came from a plot on the Experiment Station 

 Farin which was very acid, due largely to the applica- 

 tion of sulphate of ammonia in the field treatment. 

 The test ran from June 15 to September 17, 1916. 



Table III, — The Effect of Partial Sterilization of Soil 

 on the Nitrification of Pyridine, Qninoline, Etc. 



* In recording the data, fractions of a part per million were 

 frequently omitted if the nitrate content was great. 



The results which are tabulated in table III. show that 

 nitrifying organisms gained entrance to the tumblers, 

 or that the carbon disulphide treatment failed to de- 

 stroy all of the nitrifying bacteria. From unpublished 

 data obtained by the writer, he believes that the pres- 

 ence of nitrifj'ing organisms in the soil treated with 

 carbon disulphide was not due to contamination, but 

 to the fact that the organisms w^ere not killed by tlie 

 antiseptic. 



Carbon disulphide inhibited nitrification in the un- 

 treated soil and in the soil treated with dried blood or 

 quinoline, and serioush^ reduced the process in soil 

 treated with pj^ridine or piperidine. In the presence of 

 lime, the antiseptic reduced nitrification in the un- 

 treated soil and in the soil treated with dried blood or 

 with quinoline. On the other hand, with carbon di- 

 sulphide and lime, more nitrates were formed from 

 pyridine and from piperidine than were obtained from 

 these compounds alone. The effect of reinoculation 

 was to increase in all cases the amounts of nitrates 

 recovered. 



