29 SOILS OF THE TRUCKEE-CARSON IRRIGATION PROJECT. 
not in close agreement, although high alkali consisting of both 
chlorids and sulphates is apparently correlated with low isa 
Little if any difference is to be noted between the effect of the chlorid 
and the sulphate types 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 
PARTS PER MILLION OF CHLORIDS AND SULPHATES. 
Masane ee 
Fig. 15.—Diagram showing the relation between the quantity of alkali and the nitrification in samples of 
soil from plats 180, 120, 170, 100, 190, 150, 160, and 110, Truckee-Carson Experiment Farm. Samples 
taken from depths of 6 to 12 inches. 
PARTS PER MNLLION OF NITROGEN AS NITRATES. 
cent of potassium nitrate, and the free nitrogen gas evolved was 
measured. This medium favors the growth of this 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 
