73 



The Effect of Non-Xitrogenous Substances Toxic 

 TO Plants in Water Cultures, on the Nitrification 

 OF Dried Blood, Pyridine, Etc. 



Davidson (3) has shown, that the addition of vanillin 

 or cumarin to soil which had hcen treated with lime, 

 sodium nitrate, or potassium chloride, decreased ni- 

 triticalion; while, in the presence of disodium phos- 

 phate, there was greater nitrification in tlie vanillin and 

 cumarin treated soils tlian in the controls. He suggests 

 that the action of vanillin and cumarin on nitrification 

 may he anah)gous to tlie hehavior of soluble organic 

 matter in general. 



The writer studied the effect of vanillin, cumaiin, 

 pyrogallol and salicylic aldehyde on the nitritication 

 of dried l^lood, pyridine, quinoline, piperidine and 

 guanidine carbonate, in both limed and unlimed con- 

 ditions. The methods emploj^ed were the same as in- 

 dicated above. 



Two soils were nsed, one of which, a Norfolk sandy 

 loam, was obtained from the Cullers rotation plots; 

 and the other was obtained from the very acid plot 

 on the Experiment Station Farm. 



In" the slightly acid Norfolk sandj^ loam soil, as can 

 be seen from table IV. dried blood, pyridine and piperi- 

 dine produced notable increases in the nitrate content 

 of the soil. From quinoline, how^ever, not quite as 

 much nitrates were produced as from the soil treated. 

 w4th water only. The addition of lime to quinoline^ 

 inhibited nitrification; but, with dried blood, pyridine, 

 and piperidine, lime increased nitrification. 



Pyrogallol alone retarded nitrification of dried blood 

 and pyridine, but slightly increased nitrate formation 

 from quinoline and piperidine. Comparing the pyro- 

 gallol-lime series with the nothing-lime series, less 

 nitrates were obtained in the presence of pj'^rogallol 

 than where it was absent. It is apparent, however, 

 that the inhibitory action of pyrogallol is quite largely 

 overcome by lime. 



Vanillin alone practically inhibited nitrification of 

 pyridine and quinoline, seriously reduced the process 

 with dried blood, but had very little effect on the ni- 

 trification of piperidine. Lime reduced to a marked 

 degree the toxic action of vanillin toward the nitrifica- 

 tion of pyridine and dried blood. In no instance was 

 the nitrate content of the vanillin-lime series as high 



