THE NITRIFYING EFFICIENCY OF CERTAIN COLORADO SOILS 
11 
DESCRIPTION OF THE SOILS 
Colorado Soils 
Sample No. 75.—The first soil that we shall consider was collected 
at Fort Collins April 29, 1913. The land had been in barley the pre¬ 
ceding year and in sugar-beets the year before that. It is what would 
be considered a normal clay soil for this section of the state; level, 
well drained, and free from any trace of white alkali and brown discol¬ 
oration. In 1913, it produced an average of 45 bu. of wheat to the 
acre and in 1911, 24 tons of sugar-beets per acre. This sample was 
composed of twenty sub-samples taken to a depth of six inches over an 
area of one-half acre. The nitric nitrogen amounted to 7 p. p. m. and 
the chlorin to 500 p. p. m. 
Sample No. 76 .—For the next sample, we went to an altitude of 
almost 9000 feet to a truck patch nestled in a gulch on the outskirts 
of a mining town. This is the only tract of its kind which Nature has 
allowed in the vicinity and which, I should judge, has an area of less 
than twenty acres. It is more than 3000 feet above and 36 miles from 
any known niter area, and, so far as could be learned, it is perfectly 
normal. However, it has an an added interest from the fact that pre¬ 
vious to its present ownership it was held as a placer gold claim. The 
soil is a deep river-bottom silt loam and has been maintained in a very 
productive condition in recent years by the heavy application of stable 
manure. In 1911, the owner harvested 240 sacks (over 450 bushels) of 
potatoes to the acre. All kinds of vegetables and small fruits, especially 
strawberries, are grown here very successfully. At the time this sam¬ 
ple was collected, May 11, 1913, nothing had been planted, and the 
ground was covered with a very liberal dressing of manure. This 
was removed as far as possible before taking the sample, but the heavy 
snows of the preceding winter and spring must have caused some 
leaching. Just how much this had affected the nitrates of the surface- 
layers, we have no means of knowing, but it undoubtedly contributed 
something. The nitric nitrogen amounted to 54 p. p. m. and the chlorin 
to 400 p. p. m. 
Sample No. 77.—This soil came from a tract that we have had un¬ 
der observation since 1908. At that time it was planted to oats, but 
the stand was very spotted. Throughout the field barren patches were 
developing, brown in color and mealy in texture. Alfalfa growing 
had been abandoned in previous years because it was believed that the 
water table was getting so close to the surface that this crop could 
not succeed. In the light of our present knowledge, it is possible that 
it was the excessive nitrates rather than too much water that was in¬ 
juring the alfalfa. In 1909 sugar-beets were planted, but with no 
better results. The brown areas kept increasing in number and size 
until there were patches of half am acre in extent where nothing 
would grow. That fall it was planted to winter wheat, but before the 
harvest of 1910, the whole twenty-five acres had died. I visited the 
place in 1911 and found that Russian thistles and salt bush had taken 
