54 Colorado Experiment Station 
advisable to state how much they may mean. The annual evaporation 
from a free water surface in the San Luis Valley may be taken as 60 
inches, and from a soil surface as 30 inches. The drainage water car¬ 
ries 159 p.p.m., or each million pounds of water carries 159 pounds of 
sodic carbonate. If 3 acre-feet of such water were evaporated to dry¬ 
ness on an acre of land, and the whole of the carbonate were left on 
the surface, it would mean the deposition of 1,300 pounds of sodic 
carbonate, which would add, if thoroughly mixed through the top foot 
of soil, 0.03 percent of sodic carbonate. In experimenting with beet 
seedlings years ago, I ascertained that the presence of 0.05 percent of 
this salt in the soil was injurious and could not be exceeded without 
killing the seedlings. This is the importance of the preceding figures, 
i. e., the ground- and drainage-waters, and all of the artesian wells 
in this area contain sodic carbonate. The brown artesian waters are, 
for all purposes proper to consider at this time, simply weaker or 
stronger solutions of this salt. This is true to such an extent that we 
illustrate it by the following statement: If a gallon of brown water 
contains 70 grains of salts in solution, 63 grains of these 70 grains are 
sodic carbonate or black alkali. The presence of this salt is a fully 
adequate and satisfactory explanation of the fact observed by many 
ranchmen that artesian water is not so good for irrigating purposes 
as ditch, or river-water, which is a conservative statement, for many 
of them have observed that the brown waters are fatal to vegetation. 
The water from one of the wells mentioned in the preceding table 
flowed over some land for a few months and the owner told me that it _ 
was several years, four years I think, before he succeeded in overcom¬ 
ing its effects. 
I have previously stated that, for our view of agricultural con¬ 
ditions, we can consider this black alkali, sodic carbonate, as existing 
in strata of this country to a depth of at least 900 feet, for we find 
the water of cased, artesian wells becoming richer in this salt till we 
gain this, approximately our greatest depth. We certainly do not need 
to concern ourselves about the more remote origin of the salt so far 
as it pertains to the agricultural questions of the section. 
UNFAVORABLE CONDITIONS PREVAIL WHEREVER WATER IS 
ALKALINE 
An important consideration in this connection is the actual soil 
conditions that obtain. If these contradicted the views set forth, we 
would certainly conclude that their presentation was worse than un¬ 
wise. It is, hozvever, a fact that the unfavorable agricultural condi¬ 
tions and the alkaline character of the water are coincident in their 
occurrence, which is of itself very suggestive. 
