Be SOILS OF THE TRUCKEE-CARSON IRRIGATION PROJECT, 
Table [X shows the difference between the good and poor soils in 
regard to total numbers and distribution of bacteria. The difference 
in the floras is more strikingly brought out when we consider the 
difference in the colonies from the different soils. The plates from 
the 6-inch and 12-inch layers of plats 300 and 310, which show low 
numbers, chiefly contained peculiar colonies surrounded by a wine- 
colored diffusible pigment. The colony itself was but slightly colored 
and, surrounded as it was by this pigment, produced a very striking 
appearance on the plates. One plate from plat 310 was apparently a 
pure culture of this organism. Such a plate obtained from soil where 
the growth or flora is almost always rich and varied is very rare, and 
is the only unusual condition thus far encountered that seems to cor- 
relate consistently with the unusual conditions of infertility. This 
peculiar colony was never seen on soils from the fertile spots, and the 
fact that it was so predominately present in the infertile soils and in 
those strata in which the peculiar. black layer occurred certainly in- 
dicates that further study should be made of this point. Microscopic 
examination of the colony showed that it was a micrococcus associated 
with a mold. 
TaBLE 1X,—Total number of bacteria present ir 1-gram samples of soil from plats 
"300, 310, 320, 330, 340, and 350, Truckee-Carson Experiment Farm. 
No. of Depth of Number of Character 
plat soil bacteria of soil = 
: ; per gram, senate 
Inches 
300 0-6 458,400 | Poor. 
6-12 45, 000 
12-18 48, 900 
18-24 178, 500 
310 0-6 1,930, 500. Do. 
6-12 729, 000 
12-18 15, 900 
18-24 409, 500 
320 0-6 507,000 | Good. 
6-12 351, 000 
12-18 419, 000 
18-24 429, 000 
330 0-6 1,335,000 | Poor. 
6-12 915, 000 
12-18 840, 000 
18-24 1,197,000 
340 0-6 4, 200, 000 Do. 
6-12 525, 000 
12-18 4, 620, 000 
18-24 3, 780, 000 
350 0-6 672, 000 xo00d. 
Gal isso bs wie ees 
12-18 636, 000 
18-24 210, 000 
CONCLUSIONS. 
(1) Nitrifying, denitrifying, and ammonifying bacteria are well 
distributed and universally present in the soils of the Truckee-Carson 
Irrigation Project and become physiologically active if favorable con- 
ditions are provided for their development. 
211 
