14 SOILS OF THE TRUCKEE-CARSON IRRIGATION PROJECT. 
practically failed to nitrify,' although the two plats appear to be very 
sunilar. 
Figure 5 shows the relative nitrifying power of good and poor soils 
collected from adjoining plats. Plat 160 has a loose sandy soil to a 
DEPTH AT WHICH SAMPLES WERE TAKEN. 
127018" 187024" 247036" 
FAPPTS FEF? /4/LL/OQNM OF CHLOAIDS ANDO SULPHATES. 
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X 
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Fic. 5.—Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plats 160 and 170, Truckee-Carson Experiment Farm. Original nitrate present in samples from 
plat 160: Depth, 0 to 6 inches, 8.64 parts per million; 6 to 12 inches, 2.88;°12 to 18 inches, 4.8; 18 to 24 inches, 
6; 24 to 36 inches, 4.8. From plat 170: Depth, 0 to 6 inches, 4.32 parts per million; 6 to 12 inches, 6; 12 to 
18 inches, 3.84; 18 to 24 inches, 3.6; 24 to 36 inches, 3. 
depth of 18 inches; below this it is very heavy, but below 26 and 30) 
inches it is again lighter in texture. At the time of sampling, this | 
plat was supporting a fine growth of alfalfa. Plat 170 is in the north- | 
east corner of the same field, and was very similar except: that the 
1 This field had been irrigated a short time before the samples were collected. 
211 
