16 SOILS OF THE TRUCKEE-CARSON IRRIGATION PROJECT. 
held together by some cementing material. As shown in figure 6, the 
nitrifying power of samples from plat 180 is almost nothing. In this 
figure the chlorid and sulphate curves are of interest, as those of plat 
180, the poor soil, are far. above those of plat 190, the good soil.* 
SULPHATES. 
N 
S 
S 
g 
X 
. 
: 
< 
S 
FARTS PER MILL/ION OF 
S 
= 
= 
Ni 
. 
& 
e 
N 
S 
v 
Fic. 7.—Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plat 200, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, 0 to 6 
inches, 7.68 parts per million; 6 to 12 inches, 5.8; 12 to 18 inches, 3.93; 18 to 24 inches, 4.32; 24 to 36 inches, 
1.82. 
Figures 7 to 10, inclusive, show the nitrifying power of samples of soil 
from plats 200, 210, 220,and 230. They are in fields which have only 
recently been leveled and irrigated; in fact, 1909 was the first year 
they had been cropped. They produced a fair crop of barley, but the 
DEPTH AT WHICH SALIFLES WERE 7AKEN- 
) O76" 7012" i270! 7024" 7036" 
Se 20 670 27018" 187024 247036 00 & 
=X \ 
SS Se 
NN Se 
NR NY 
Vy Si 
GN GN 
us GS 
y LOH 
© 
PS Q 
SSS e 
ASS 
= 
Fic. 8 —Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plat 210, Truckee-Carson Experiment Farm. Original nitrate present in samples: Depth, 0 to 6 
inches, 2.66 parts per million; 6 to 12 inches, 4.8; 12 to 18 inches, 4.16; 18 to 24 inches, 3; 24 to 36 inches, 2. 
young alfalfa sown in the barley was doing only fairly well. The 
curves from all of these plats show a very low nitrifying power, yet a 
glance at the figures shows that nitrates were present in moderate 
quantities in the original samples. 
! Bridge readings on these samples were made by Mr. Jensen. 
a 
