4 g The Colorado Experiment Station 
rich in nitrates that the nitrogen fixing flora has practically per¬ 
ished. One thing is characteristic of them all, 1. e., the brown cota 
of the soil, hence the common term “black alkali. This is most 
striking along the roadsides where we sometimes can observe the 
dark color continuous for as much as a mile at a time. m samp e- 
were taken from such places. The dark color is possibly due to 
the bacterial flora itself as the azotobacter form yellow brown or 
dark brown films. The following numbers are simply laboratory 
numbers for a preliminary series and may not again be 
this of course is entirely in Professor Sackett s hands. Professor 
Sackett found that these samples were comparatively rich in nitro¬ 
gen fixing bacteria of which he finds a considerable variety, it is 
not time to state any conclusion even tentatively held. Professoi^ 
Sackett has given me the following results which may suffice 01 
the present purpose, i. e., to place the source of these nitrates be- 
ond a reasonable doubt. The nine samples represent five localities. 
V 
Number 1. 
A surface soil very rich in nitrates. 
Number 2.—This sample is from the same locality taken to a depth of 
6 inches. 
Number 3.—Same locality 12-14 inches deep. 
Number 4.—Taken as normal soil for this locality, 
water at a depth of five feet. 
Number 5.—Another locality from 2-6 inches deep. 
Number 6.—Another from 2-6 inches deep. 
Number 7.—Another locality from 2-6 inches deep. 
2-6 inches deep, no 
Number maf mesa" Z In an alfalfa field with no apparent 
trouble. 
NITROGEN FIXATION. 
Milligrams Nitrogen Fixed in 100 CC. Mannite Solution, Infusion of 10 
Number 1 
Grams of Soil Added. 
10 Days 
0.00000 
Number 2 . . 1.78627 
Number 3. . 3 9278O 
0.63045 
0.07213 
1.72130 
1.87562 
4.13431 
4 
5 
6 
7 
20 Days 
0.00000 
1.19085 
3.08220 
6.16440 
0.84060 
0 77055 
3.50250 
2.38170 
13.02930 
30 Days 
1.05075 
0.56041 
3.43245 
12.46891 
3.08221 
3.57265 
3.01215 
2.87205 
10.15725 
Number 
Number 
Number 
Number 
Number 8 
Number 9 . .. . . 
All questions of technique and further detail will be presented 
by Professor Sackett in due time. _ 
The great variety of soils in which I have observed this trouble 
and the variety of differences in the appearances of these places 
make one hopeful of very interesting results. 
We may be pardoned for adding the following consideration 
possibly of some geological interest. The source of the nitroger 
present in the Chile saltpetre beds has been the cause ot muc 
speculation. The source of the nitrogen in the India saltpetre eartl 
is considered as evident and the formation of the nitrates is sut 
ficiently accounted for by the action of nitrifying bacteria, wind 
