DETAILED STUDY OF SOIL TVriCAL OF EXTENSIVE AREAS. 



27 



Winogi-julsky's solutions unci also into flasks of sterile Avater, from 

 which counts were made. The remaining portions of the samples 

 were then emptied on clean sheets of paper in the culture room and 

 left to dry under conditions as free as possible from chance contami- 

 nations. Fifty-gram i)ortions from each sample were removed for 

 original nitrate determinations, and another equal portion was re- 

 placed in the original containers, brought up to optimum moisture 

 content with 5 cubic centimeters of 0.4 per cent sulphate of ammonia 

 and distilled water, incubated for two weeks at 28° C, and the nitri- 

 fication determined. A duplicate series to which was added a 2 per 

 cent solution of calcium sulphate was prepared. At the beginning 

 of the incubation period the total weight of the container and soil 

 at optimum moisture was taken, and the loss from evaporation was 

 restored with sterile distilled water at 3-day intervals during the 

 incubation period. The results of the experiment appear in Tables 

 IV and V. 



Table lY .—Effect of calcium sulphate upon nitrification in samples of soil from pints 

 mo and .no] Truckee- Carson Experiment Farm, representing poor soil conditions. 

 Incubated 15 days at 28° C. 



NO CALCIUM SULPHATE ADDED TO SAMPLES. 



WITH 2 PER CENT CALCIUM SULPHATE ADDED TO ALL SAMPLES. 



211 



