Ly SOILS OF THE TRUCKEE-CARSON IRRIGATION PROJECT. 
NITRIFYING POWER OF SOILS AT DIFFERENT DEPTHS. 
In investigations in soil bacteriology in the eastern United States 
only the surface soil shows great variations. The soil of the arid 
sections is much deeper, however; that is, the subsoil is less “‘raw”’ 
than in regions of heavier rainfall, a fact that has come to be more 
or less familiar to everyone studying soil conditions over extensive 
areas. 
Figure 2 shows the nitrification of samples from plats 100 and 110. 
These plats, which are practically duplicates, are in a productive 
DEPTH AT WHICH SAMPLES WERE TAKEN. 
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FARTS PEP MULLION OF CHLOFIDS AND SULFHATES. 
Fic. 2.—Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plats 100 and 110, Truckee-Carson Experiment Farm. Original nitrate present in samples from 
plat 100: Depth, 0 to 6 inches, 8 parts per million; 6 to 12 inches, 15; 12 to 18 inches, 9; 18 to 24 inches, 4.8; 
24 to 36 inches, 6.56. From plat 110: Depth, 0 to 6 inches, 9 parts per million; 6 to 12 inches, 7.4; 12 to 
18 inches, 5.2; 18 to 24 inches, 4.8; 24 to 36 inches, 3.12. : 
alfalfa field which has been under cultivation for several years. The 
soil is loose and sandy throughout the 3-foot depth. The nitrate 
curves show that there is a gradual decrease in nitrifying power with 
depth. 
Figures 3 and 4 show the nitrification in samples from plats 120 and 
130. These are in a fertile alfalfa field similar to the one mentioned 
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