6 
Colorado Experiment Station 
over-estimates. More especially has he been led to over-estimate 
the injurious effects of these salts. I remember the impression 
made upon me by the whiteness of the country west of Alamosa 
during a trip in the spring of 1914. For more than two miles the 
surface of the ground on both sides of the road was perfectly 
white and this condition extended, especially to the southward, 
as far as one could see. I measured this efflorescence at some 
points and found it attaining a thickness of one-quarter of an 
inch or rather more. I took a sample of this, analyzed it, and 
found it to contain more than 91.0 percent of sodic sulfate. It is 
not a matter that should cause surprise that such a condition should 
impress one as very bad indeed, but I do not believe that it is a 
fact that it is very bad. 
Some years ago I took some samples of soils at La Jara. 
Among them there were two from a field planted to peas; the 
stand was irregular but the peas were thrifty. These two samples 
represented 6 inches of soil, the top 2 inches and the succeed¬ 
ing 4 inches. The top 2 inches carried 3.0 percent of salts 
soluble in water; the next 4 inches 1.5 percent. Of these salts, 
65 and 46 percent respectively were sodic sulfate, the rest, essen¬ 
tially, calcic sulfate. The peas undoubtedly had pushed their 
roots to a greater depth than 6 inches, but they had passed 
through this 6 inches and they were thrifty. I have seen just 
as marked instances in the eastern part of Alamosa, where a good 
lawn and garden were separated from land heavily charged with 
this “white alkali” by an ordinary picket fence. In this case the 
effloresced alkali contained 96 percent of sodic sulfate. These 
are only a few instances of this character that I have met with 
which lead me to believe that ordinary, so-called white alkalis are 
of themselves not sufficiently injurious to justify their considera¬ 
tion in this connection. 
“BLACK ALKALr POISONOUS TO PLANTS 
There is a so-called “black alkali”, which consists essentially 
of sodic carbonate, whereas the “white alkali” consists essentially 
of sulfates. The “white alkali” does not discolor the land; the 
“black alkali”, when the soil contains much organic matter, gives 
rise to very dark, almost black, solutions and crusts, for which rea¬ 
son it is called “black alkali”. The alkali itself is not black, it is 
white, just as white as the so-called white alkali, but it dissolves 
organic matter (humus) with a brown or black color. This alkali is 
so corrosive that it will destroy the tissues of young plants and even 
of older ones, and, of course, may kill them. Another effect of sodic 
carbonate, “black alkali”, is to make the ground puddle and cake so 
