Alkalis In Colorado 
57 
I have stated fully, without any reservations, the occurrences and com¬ 
position of these alkalis, of the river-waters, of the ground-waters, of 
the soil, and of the well-water to a depth of 923 feet,and in none of these 
did we find any unusual amounts of nitrates, except in the brown spots, 
some of which proved to be so rich in nitrates that nothing would grow 
on them. The surface portions of the richest of these carried 5.6 percent 
of nitrates, calculated on the dry surface soil. These spots may be found 
anywhere in the San Luis valley, near the mountains or 20 miles away 
from them, but this would make no difference for there are only two 
things in thjs landscape, the mountains and the valley floor. There 
are no mesas, shales, or high lands from which these nitrates might 
come ; besides, they are just in spots at first, though they may become 
numerous enough and grow big enough to run together and cover the 
better part, or the whole, of a large area of land. 
I have explained how they come to be in these places, how the 
little plants enrich the soil in nitrogen by taking it from the atmosphere, 
how they, like other plants, die and their substance undergoes changes 
as other organic matter does. In our soils a large proportion of their 
nitrogen is changed into nitric acid or nitrates. So the nitrogen which 
is changed into nitric acid to form these nitrates does not come from 
the rocks, either as nitrogen or as nitrates, as the soda, lime, mag¬ 
nesia, chlorin and sulfuric acid, that form the white alkalis do, but is 
taken from the air by these plants just as truly as the carbonic acid is 
taken from the air by water which helps it to build up carbonates with 
the lime, magnesia and soda of the rocks. 
SUMMARY 
The alkalis that we usually meet with in Colorado are for the most 
part “white alkalis”. 
In a great many cases these are simply washed from the higher 
parts of the fields into lower parts, where the water gathers and, hav¬ 
ing no way to flow out, fills up the hollow and is removed by evap¬ 
oration, leaving the alkalis. In this way a very bad-looking spot may 
grow to a considerable size. If this water could be let out by a drain 
this would be stopped. 
When water carrying alkalis has to sink through the soil some 
of the alkalis are retained and the same is true of shales, so if moderate 
amounts of water have annually fallen on the surface where some 
alkali has formed, it will move it downward to leave it at a little lower 
level, so that together with the changing of any sulfide of iron by the 
action of the air, which will help to form sodic and calcic sulfate, any 
water that seeps out of banks of such materials may and often does 
carry a large amount of sulfates. Such waters should, if possible, be 
drawn out of a section by drains. 
