71 



Taiile II. — Effect of Varying Amounts of Nitrogenous 

 Compounds on the Rate of Nitrification. 



Treatment 



Dry checks 



Distilled water 



Dried blood 



Asparagine 



Napthylaniine- 



Alloxan 



Nucleic acid __ 



Quiiioline 



Pyridine 



NO ; in p. p. ni. of air dry soil from 







137 



231 



0.5 gram 



0.25 gram 



1225 

 175 



187 

 187 

 360 

 175 

 200 



850 

 550 

 lost 

 200 

 237 

 200 

 212 



1 gram 



525 

 486 

 175 

 525 

 625 

 200 

 225 



With the exception of dried blood and naphthyla- 

 mine, more nitrates were formed from ten tenth gram 

 treatments than from the half gram treatments. The 

 heavier applications of asparagine, alloxan, and nucleic 

 acid exerted a decided inhibitory etfect on nitrification. 

 Compared with the distilled water check, pyridine, and 

 quinoline slightly retarded nitrification. It is probable 

 that this experiment was of too short duration for the 

 last named compounds to be decomposed in the very 

 poor soil used. Or, the two grains of lime per tumbler 

 may have retarded their nitrification, since in other 

 experiments lime has been found to l3e inhibitory to 

 the decomposition of quinoline, and of but little benefit 

 to the decomposition of pyridine. 



The Effect of Partial Sterilization of Soil on 

 Nitrification of Pyridine, Quinoline, Etc. 



In view of the fact that various investigators have 

 l-eported that treahnent of the soil with carbon disul- 

 phide destroys the nitrifying organism, it was thought 

 of interest to study the effect of "partial sterilization" 

 on the nitrification of these compounds. Carbon di- 

 sulphide was added to a number of tumblers in suffi- 

 cient quantity to moisten about one half of the 100 

 gram samples of soil used. After standing covered for 

 about 21 hours, the soil in the tumblers was exposed 

 to the air and allowed to stand for about ten days so 

 as to rid the soil of the antiseptic. One series received 

 no lime, a second series was limed, and a third series 

 was limed and reinoculated with an infusion from the 

 untreated soil. During the time that this experiment 

 was in progress, no special attempt was made to avoid 

 contamination of the soil treated with the antiseptic. 

 However, distilled water was used throughout, and 



