32 The Colorado Experiment Station 
ANALYSIS XXIX. 
RESIDUE FROM DRAIN WATER. Laboratory No. 792. 
Per Cent. 
Calcic Sulfate . 22.352 
Magnesic Sulfate . .. 31.586 
Potassic Sulfate . 1.502 
Sodic Sulfate . 24.775 
Sodic Chlorid . 9.050 
Sodic Carbonate . 4.120 
Sodic Nitrate . 6.500 
Silicic Acid . 0.115 
100.000 
These results show what is pretty well demonstrated by the 
other samples, i. e., that the presence of the nitrates in the waters 
is not an accidental but a regular occurrence. 
I have now presented all of the analytical data which I propose 
to present in this bulletin to show the occurrence of excessive 
amounts of nitrates in certain of our soils. These occurrences are 
not confined to one section of the state; the samples given represent 
widely separated sections. 
There are no data that I have been able to find relative to the 
amount of nitric acid, respectively nitric nitrogen, in soils in gen¬ 
eral. The most satisfactory statements have been found in the 
latest edition of Storer’s “Agriculture.” These statements are large¬ 
ly based on the Rothamsted experiments and give aggregate results 
which are very difficult to apply to our lands, or to use in answering 
the questions suggesting themselves. We, therefore, collected a 
number of samples, representing the surface portion of our soils, 
because it is only with the upper layers that we are concerned. The 
percentages of nitrates given in the preceding analyses varying 
from 0.2 to upwards of 5.0 per cent of the air dried samples will 
not appeal to some readers as large quantities, therefore we wish 
to know and present what some other surface soils in Colorado 
contain. We are aware that the content of nitric nitrogen in a 
soil varies from time to time and that the nitrates may be carried 
down to considerable depths by rain water, etc.; all of these things 
have but little bearing on the object had in view. We wanted to 
know how much nitric nitrogen we might expect in the soil to a 
depth of 2j/2 feet, for our samples have mostly been taken at less 
depths, in fact the most remarkable quantities have been found 
practically within the first half inch of soil, though some very 
large percentages have been found at as great depths as three 
inches. We determined on sampling different sections of the Col¬ 
lege farm. The samples were taken in October during a period of 
fine weather and no irrigation water had been applied for some 
weeks. Other detailed data of this character are not at my dis¬ 
posal. This study was entrusted to Mr. Douglass and the following 
is his report: 
