28 The: Colorado Experiment Station. 
that drainage is not of itself and necessarily a cure, and still 
further to show that these nitrates are not deposited by the evap¬ 
oration of ground water coming from other lands. The owner 
explained to me that the depth of the drains vary—which is evident 
without statement—but he added that the gravel below the soil 
is very irregular in its surface so that the depth of gravel penetrated 
by the drains is quite different. We will not consider any greater 
depth of soil than is represented by our samples, i. e., two inches, 
but we will calculate how much of this drain water would be 
required to furnish the nitrate which we actually find in these 
two inches of soil, and we will take this as 2,150 pounds. The 
samples of soil and drain water were taken in May, 1911. The 
drain water contains 0.1 part per million of nitric nitrogen equiv¬ 
alent to 0.6 part per million sodic nitrate; taking an acre-foot of 
water at 2.7 million pounds it gives us 1.62 pounds of nitrates 
per acre-foot of water and we would have to evaporate 1,327 acre- 
feet of this drain water to obtain this 2,150 pounds of nitrates 
which we find present at this time. The evaporation of this amount 
of water would require, assuming that the annual evaporation 
amounted to sixty inches (at Ft. Collins it is only 41 inches) two 
hundred and sixty-five years. This drain water carries 8,489 
parts of total solids per million which, calculated on the 1,327 acre- 
feet of water necessary to yield the 2,150 pounds of nitrates, would 
yield 30,414,840 pounds of salts, a quantity sufficient to cover the 
land more than seven feet deep, if we suppose them to have the 
same density as the soil itself. 
The changes in the conditions of these soils have taken place 
within the past few, say six, years, and these conclusions to which 
we are forced if we suppose that these nitrates have their origin 
in the evaporation of the ground waters are evidently false. We 
know that no 1,327 acre-feet of water have evaporated to dryness 
on this land in this time and it is evident that our country is not 
covered nearly eight feet deep with calcic chlorid and other salts 
and we are likewise quite as sure that land which up to six years 
ago, and this assumed period is from three to six times as long as 
the facts indicate, has not been two hundred and sixty-five years in 
going to the bad. 
I have described the condition of the land north and east of 
north of this orchard, designated No. 8, and from one-fourth to 
one-half mile distant, as having the natural color of ordinary 
adobe soil, in 1907 and 1908, with an abundance of ordinary white 
alkali in its surface portions, and stated that sulfate of soda 
crystals up to two and a half inches long occurred in the lower 
portions of this land, especially in depressions in the surface soil. 
In the spring of 1911 practically the whole surface in this land is 
dark brown in color and greasy in appearance. I dug a hole four 
