“Black Alkali” in the; San Luis Valley 
5 
in regard to its content of phosphoric acid and potash. The nitro¬ 
gen is not given in this analysis, but judging from the amount of 
this element found in other samples, it is probably about 0.10 of 1 
percent. The question of exhaustion of this soil, even if we 
assume that the addition of nitrogen would be advisable, can be 
dismissed as the cause of the unproductiveness of this large sec¬ 
tion of the country. 
“WHITE ALKALI” IS NOT INJURIOUS 
Another cause often assigned for an unproductive condition 
of our lands is “white alkali”. That there is alkali in this, as well 
as in other sections of the valley, is thoroughly well known. There 
is more evidence of this class of alkalis outside this section than 
within it. 
It is natural that, when a section of country measuredfin square 
miles is covered by a white efflorescence, perhaps literally as 
white as snow, that it should make an impression upon one as an 
important factor in any unproductiveness of the land which may 
be observed. That this has been the case and has been passed on 
from one to another and from one section of country to another 
from the beginning of our agriculture till the present time is true, 
and it is unfortunate that it is true, for, whatever the results of 
laboratory experiments may be, I have yet to see the proof that 
these “white alkalis” constitute any seriously unfavorable factor 
in our field practice. When something is wrong, many of us, 
especially if we have not learned that it is no disgrace to acknowl¬ 
edge that we do not know everything, attempt to give a reason 
for the condition, whether it has anything to do with the question 
or not. In this way our ordinary “alkali” has been assigned as 
the cause of much evil. 
I do not intend to go into this question here, but I may state 
that the alkali question is more complex than the average person 
imagines and includes much more than the white efflorescences so 
abundant, especially at times during the spring months, in some 
sections of the valley. This white efflorescence, our ordinary 
“white alkali”, as it occurs west and south of Alamosa, or very 
generally throughout the valley, is essentially sodic sulfate, often 
mixed with calcic sulfate. I do not believe that these salts occur 
in these soils in sufficient quantities to cause any damage. The 
general reader should be reminded that these salts, as he sees 
them on the surface of the country, are what is left from the 
evaporation of large amounts of water which have brought them to 
the surface of the soil and left them there in the form of a very 
strikingly white powder whose quantity in the soil he greatly 
