75 



Table V. — The Effect of Non-Nitrogenous Snhslances 



on the Nitrification of Dried Blood, Pyridine, Etc., 



in Acid Soil from the Experiment Stcdion Farm. 



Nitrates Expressed as p. p. m. of Dry Soil. 



Pyrogallol alone materially retarded the nitrification 

 of dried blood, pyridine and quinoline, and slightly 

 retarded nitrification of piperidinc. Compared with 

 die nothing-lime series, pyrogallol with lime increased 

 the nitrification of dried blood, pyridine and piperidinc, 

 but inhibited the process with quinoline. 



In the presence of vanillin alone, each of the com- 

 pounds was nitrified less than when vanillin was absent. 

 On the other hand, two of the compounds were nitrified 

 more with vanillin and lime than with lime alone. Just 

 why the combined action of pyragallol and lime, or 

 vanillin and lime, should favor nitrification more than 

 docs the lime alone, is not clear. 



By the addition of cumarin, nitrification of dried 

 blood and piperidinc was reduced considerably below 

 that found in the nothing series. Pyridine and quin- 

 oline, however, were nitrified as well with cumarin 

 present as without cumarin. In the presence of lime, 

 the inhibitory effect of cumarin on the nitrification of 

 dried blood and piperidinc was materially reduced; 

 while there was no effect from lime in the pyridine- 

 cumarin treated soil. Lime in addition to cumarin 

 completely inhibited nitrification of quinoline. 



Salicylic aldehyde inhibited nitrification in all in- 

 stances except with piperidinc, in the presence of 

 which compound a small amount of nitrate was found 

 in the unlimed series. Salicylic aldehyde persists in 

 soils longer, as indicated by smell, than any other com- 

 pound used in the experiments here reported. 



