& NITRIFYING POWER OF SOILS AT DIFFERENT DEPTHS. Les 
surface was a little more compact and the alfalfa was practically a 
failure. The nitrification curves show the same general variations, but 
the one of the poor soil is consistently below that of the productive soil. 
i DEPTH AT WHICH SAMPLES WERE TAKEN. 
! O76 — 7012" 127018" 187024" 247036" 
Chlorids- 
PARTS PER [/LLION OF CHLOFIDS AND SULPHATES. 
WH) 
: 
S 
= 
Y) 
x 
< 
: 
. 
= 
S 
S 
N 
S 
& 
x 
% 
: 
& 
Fic. 6.—Diagram showing the nitrification of ammonium sulphate in samples of soil from different depths 
from plat 180 (poor soil) and plat 190 (good soil), Truckee-Carson Experiment Farm. Original nitrate 
present in samples from piat 180: Depth, 0 to 6 inches, 2 parts per million; 6 to 12 inches, 3.5; 12 to 18 
inches, 8.25; 18 to 24 inches, 4.5; 24 to 36 inches, 25.75. From plat 190: Depth, 0 to 6 inches, 4.5 parts per 
million; 6 to 12 inches, 15.75; 12 to 18 inches, 11.25; 18 to 24 inches, 20.75; 24 to 36 inches, 21.75. 
Plats 180 and 190 are located upon poor and good spots. The 
texture of the samples is very similar, both being sandy, but the 
surface of plat 180, the unproductive soil, is hard and compact as if 
211 
