81 



(5) Heavy applications oT cerlaiii nitrogenous com- 

 pounds may retard nitrification. 



(()) Liming a soil which had been parMally sterilized 

 with carbon disuli)]iide greatly increased its power of 

 nitrification, A still furtlier increase w^as obtained by 

 reinoculation of the soil after partial sterilization. 



(7). Vanillin proved to be non-toxic toward nitrifi- 

 cation of pipcridine, moderately toxic toward nitrifica- 

 tion of dried blood and pyridine and inhibitory toward 

 nitrification of quinoline. 



(8) Lime counteracted the toxicity of vanillin to 

 a very large degree. 



(9) The effect of cumarin on nitrification was quite 

 variable. In some instances it exerted an iidiibitory 

 effect; in others, none. 



(10) In most cases wdiere cumarin exerted an in- 

 hibitory effect, lime greatly reduced the amount of 

 inhibition. 



(11) Pyrogallol retarded nitrification of all com- 

 pounds, except quinoline and piperidine. In one soil. 



(12) Lime reduced the injurious effect of pj^rogallol 

 in all cases, except in the quinoline treated soil. 



(13) Salicylic aldeh^^de completely inhibited nitri- 

 fication of all compounds, except piperidine, in one soil. 



(14) Carbon black apparently overcomes a part of 

 the bad effect of certain non-nitrogenous compounds 

 on the process of nitrification. 



LITERATURE CITED 



(1) Bernthscn, A. 



11)12. A Text-Book of Organic Cliemistry. Edited and 

 and Picviscd l^v J. J. Sudljorough. 720 P. New York. 



(2) Buddin, W. 



1914. Partial sterilization of soil by volatile and non- 

 volatile antiseptics. In Jour. Agr. Sci. v. 6, pt. 4, 



p. 415. 4 fig. 



(3) Davidson, J. 



1915. A comparative study of the effect of cumarin and 

 vanillin on wheat grown in soil, sand, and water 

 cultures. In Jour. Am. Soc. Agron. v. 7, pt. 5, p. 

 221-238. 



(4) Doryland, C. J. T. 



191G. The influence of energy material upon the relation 

 of soil microorganisms to soluble plant food. N. 

 D. Agr. Exp. Sta. Bui. IIG, p. 319-401 . 



(5) Eunchess, M. J. 



1916. The effect of certain organic compounds on plant 

 growth. Ala. Agr. Exp. Sta. Bui. 191, p. 104-132, 

 8pl. 



