94 SOILS OF THE TRUCKEE-CARSON IRRIGATION PROJECT. 
Taste II.—Denitrification in solution of samples of soil from plats 180, 190, 230, 260, 
270, 280,! and 290,! Truckee-Carson Experiment Farm. 
| 
No. of Depth of |Gas formed Gas formed | 
| plat. soil. in 7 days. | in 15 days. | 
Inches. Per cent. Per cent. 
180 | 0-6 2a) = | 25 
6-12 20 30 
| 12-18 20 25 
190 0-6 22 32 
6-12 30 | 40 
12-18 32 42 
230 20 30 
6-12 21 30 
12-18 20 35 
260 0-6 40 | 53 
6-12 15 | 23 
12-18 20) 30 
270 0-6 74) |) 30 
6-12 20 30 
12-18 20 | 30 
280 ! 0-6 00 00 
6-12 Trace Trace. | 
12-18 Trace Trace 
2901 0-6 29 | 40 
6-12 10 18 
12-18 45 62 
1 Plats 280 and 290 are located in an old alfalfa field one-fourth mile north of Fallon. 
RELATIVE NUMBERS OF BACTERIA IN DIFFERENT SOILS. 
An estimation of the number of bacteria in a gram of soil that 
would develop aerobically upon beef agar was made for many of the 
sampling plats in accordance with the method previously described, 
the results of which are shown in Table III. Im accord with the 
reports of other investigators,! the data presented in Table III 
clearly show that the numbers of bacteria found in the different 
samples bear no consistent relation to the fertility or crop-producing 
power of the respective fields. | 
No attempt was made to determine the relative numbers of proto- 
zoa in samples of soil from the good and poor areas. If the develop- 
ment of protozoa is determined by their food supply,” in other words, 
by the numbers of bacteria existing in the soil, it is obvious that in this 
region the crop-producing power can not be limited * by the abundance 
of protozoa. 
' Léhnis, F. Ein Beitrag zur Methodik der bakteriologischen Bodenuntersuchung. 
Centralblatt fiir Bakteriologie, Parasitenkunde und Infektionskrankheiten, pt. 2, 
vol. 12, no. 6-8, June 24, 1904, pp. 262-267. 
Chester, Frederick D. The Bacteriological Analysis of Soils. Bulletin 65, Dela- 
ware College Agricultural Experiment Station, March 1, 1904. 
Voorhees, Edward B., and Lipman, Jacob G. A Review of Investigations in Soil 
Bacteriology. Bulletin 194, Office of Experiment Stations, U.S. Dept. of Agriculture, 
October 26, 1907. 
? Russell, E. J., and Hutchinson, H. B. The Effect of Partial Sterilization of Soil 
on the Production of Plant Food. Contributions from the Laboratory of the Rotham- 
sted Experimental Station, October, 1909, pp. 111-144. ; 
* Hall, A.D. The Fertility of the Soil. Seience, n. s., vol. 32, no. 820, September 
16, 1910, pp. 363-371. . 
7 ta | 
