Fixation ot Nitrogkn in Colorado Soils 41 
agreed in indicating that these crops had been satisfactory. 
Tlie object of these tests was to ascertain the fixing power of 
this soil outside of, at the edges of, and within the nitre area. 
That it has a sufficient nitrifying power is assumed, and its 
determination and statement are incidental. The samples were 
taken to a depth of three inches. The results obtained were as 
follows : 
RESULTS OBTAINED BY INCUBATING SA3IPLES OP SOIL FROM A CROSS- 
SECTION OF A NITRE-SPOT. 
Before Incubation After 30 days’ After 40 days’ 
Incubation Incubation 
Percent 
Percent 
Percent 
Percent 
Percent 
Perceun, 
Total 
Nitric 
Total 
Nitric 
Total 
Nitric 
Nitrogen 
Nitrogen 
Nitrogen 
Nitrogen 
Nitrogen 
Nitrogen 
1 
0.1320 
0.0031 
0.1435 
0.0075 
0.1770 
0.0069 
2 
0.1345 
0.0036 
0.1508 
0.0065 
0.1870 
0.0063 
3 
0.1340 
0.0050 
0.1300 
0.0111 
0.1860 
0.013,-) 
4 
0.1320 
0.0061 
0.1560 
0.0149 
0.1930 
0.0135 
5 
0.3040 
0.1950 
0.3020 
0.1970 
0.3530 
0.1840 
6 
0.3970 
0.2930 
0.3940 
0.2770 
0.4130 
0.2340 
7 
0.1335 
0.0258 
0.1580 
0.0270 
0.1920 
0.0258 
8 
0.1035 
0.0145 
0.1295 
0.0096 
0.1605 
0.0059 
9 
* 0.1340 
0.0193 
0.1520 
0.0159 
0.1840 
0.0145 
10 
0.1245 
0.0129 
0.1525 
0.0230 
0.1750 
0.0196 
These samples, from 1 to 8 inclusive, are numbered regu- 
larly from north to south across the nitre-area. The area repre- 
sented by Nos. 5 and 6 was entirely devoid of any vegetation. 
Nos. 1, 2, 3 and 4 were all supposed to be outside of the nitre- 
area. No. 1 was 150 feet. No. 2, 100 feet. No. 3, 60 feet north 
and outside of the nitre-area, while No. 4 extended up to within 
a few feet of the edge of the area. No. 7 was from a beet field 
at the south edge of the area. The presence of nitrates was 
strongly indicated by the color and the condition of the soil, 
also by the color and growth of the beets. No. 8 was also from 
this beet field, but neither the soil nor the beets indicated any 
excessive supply of nitrogen. Nos. 9 and 10 represent 60 feet 
or more in a westwardly direction, almost to the. top of the hill 
at this point. The land outside of the area shows, in round 
numbers, a fixation of 500 p.p.m. in 40 days; at the edges, 610 
p.p.m. and within the area the minimum of 160 p.p.m. Expressed 
in a different way, this soil has a high power to fix nitrogen, 
one sufficient to form 1,350 pounds of proteids in the surface 
three inches of the soil each 30 days, but near the edge of the 
