18 SOILS OF THE TRUCKEE-CARSON IRRIGATION PROJECT. 
and sulphates, as well as the curve showing nitrification, should be so 
erratic and variable. 
Figure 13 shows the nitrifying power of samples from plats 280 and 
DEPTH AT WHICH SAI4PLES WERE TAKEN. 
0706" 67012” 27018” 187024” 247036" 
PARTS PER MILLION OF NITROGEN AS NITRATES. 
PARTS PER MILLION OF CHLORIDOS AND SULPHATES. 
Fic. 11.—Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plats 240 and 250, Truckee-Carson Experiment Farm. Original nitrate present in samples from 
plat 240: Depth, 0 to 6 inches, 6.8 parts per million; 6 to 12 inches, 8; 12 to 18 inches, 10.4; 18 to 24 inches, 
6; 24 to 36 inches, 5. From plat 250: Depth, 0 to 6 inches, 28 parts per million; 6 to 12 inches, 48; 12 to 
18 inches, 6; 18 to 24 inches, 5.2; 24 to 36 inches, 7. 
290, located in an old alfalfa field just north of Fallon. These soils 
are very productive, and it was expected that they would show 
a greater nitrifying power than they did. This may possibly be 
211 
