TO May, 191-.] I iiflKi-iicc of Soil MoislKrc upon Nitrificaiion. 



•79 



In the chemical analysis the larger percentage of lime, and particularly 

 of carbonic acid, in the clav is notable as representing available base. The 

 .sandy soil with .032 carbonic acid falls below the minimum requirements.* 

 and is apparently deficient in available lime — a point which will be referred 

 to later on. 



Analytical Methods. 



Before going on to the results, the analytical methods must be briefly 

 described. 



Moisture. — At the close of the experiments, the soil in the bottles was 

 mixed, and 25 grams dried at 212 deg. F. for five hours in a tarred dish. 



Xitrate Xitrogen. — Fifty grams of the mixed moi.st soil from the bottles 

 was transferred to a small bag of nainsook, and 250 c.c. of a solution con- 

 taining 5.36 c.c. sat. potash alum + .64 c.c. formalin was poured over the 

 soil in the bag placed in a mortar. After kneading for 2 min. as much of 

 the solution as possible was transferred to a Mason jar. and 'left over 



READING THE RE.SULTS. 



night to settle. Fifty c.c.'s of the clear solution was evaporated to dryne.ss 

 on the water bath, cooled, and 20-30 drops disulphonic acid (Gill) added, 

 stirred, and left ten minutes. There was then added 15 c.c. distilled water, 

 potash till alkaline, the solution was filtered if necessary, and ma(ie up 

 to 50 c.c.'s. This solution was read in the colorimeter against standard 

 nitrate of potash. Allowance was made for the water in the moist soil. 

 -\ll solutions and salts used were tested for nitrate, and care was taken in 

 washing the bags, and preparing nitrate-free water. Chlorides were elimi 

 nated with a measured quantity of saturated silver .sulphate. The 

 analytical work was carried out bv Mr. \\". ( . Robertson, chief deputy 

 chemist. 



Results of the First Experiments. 



Table IV. gives the progress of nitrification in sandy soil, with difterent 

 degrees of moisture. Airunonia nitrogen added -^ .02121 gram per 300 

 grams soil = 70.7 parts per million. Length of incubation period — 

 27 days. Mean temperature, 66 deg. F. 



* In MinnesotA soil*. Suvder regaifls •! per cent, combined carbonic acid as the minimini from whitli 

 good results can be got ; Hall at Rothamsted adopts a similar view. 



