22 



SOILS OF THE TRtrCKEE-CAESON lERtGATlON PROJECT. 



not in close agreement, although high alkali consisting of both 

 chlorids and sulphates is apparently correlated with low nitrification. 

 Little if any difference is to be noted between the effect of the clilorid 

 and the sulphate t>^es of alkali. 



DENITRIFICATION. 



In order to test for the presence of denitrifying bacteria several 

 inoculations were made into Dunham's solution containing 0.2 per 



Fig. 15.— Diagram showing the relation between the quantity of alkali and the nitrification in samples of 

 soil from plats ISO, 120, 170, 100, 190, 1.50, ICiO, and 110, Truckee-Carson Experiment Farm. Samples 

 taken from depths of (i to 12 inches. 



cent of potassium nitrate, and the free nitrogen gas evolved was ' 

 measured. This medium favors the growth of tliis class of bacteria. 

 The conditions thus produced are abnormal and the quantitative 

 differences shown in Table II should not be taken too seriously. It 

 will be seen from the table that denitrifying bacteria are present and 

 active in almost all of the soils tested. 



211 



