“Black Alkali” in the San Luis Valley 
i3 
water was not good for it. This explains, too, the statements 
made to me by a party who had taken up a desert claim, that, “the 
more water I used, the worse I was off”. He claimed to have raised 
good crops the first year or so, but that subsequently he could raise 
nothing. I gathered two samples of alkali at this man’s place and 
found that one of them carried 40 percent and the other 15 per¬ 
cent of sodic carbonate, or “black alkali”. This man had come to 
the conclusion that he could raise nothing on this land. He hoped 
only to use it for grazing purposes. His judgment was good, for 
it was based on experience; he had tried to grow grain and alfalfa 
and they would not grow. The land contained enough sodic car¬ 
bonate to kill these plants. Some of the artesian water that he 
obtained on this place was good for domestic purposes. 
The presence of sodic carbonate explains the experience of 
another man who stated that water flowing from a well had spread 
out over a strip of ground and continued to do so for several 
months, and after this nothing would grow on this land. This 
took place several years ago and the land has not yet recovered. 
The brown artesian water is bad and the testimony of users 
of water in the valley is that they prefer river-water to artesian 
for irrigating their crops. The brown artesian waters have not 
been used for irrigating but they, as well as the water from the 
shallow well and that from the drainage ditch, show that this 
“black alkali” is in the soil and, more than this, that it is in all of 
this section of the valley down to a depth of 780 feet at least. The 
greater the depth from which the water comes the richer it is in 
“black alkali”. (See preceding analyses.) 
SUB-IRRIGATION, EVEN WITH RIVER-WATER, BRINGS 
"BLACK ALKALI** TO THE SURFACE BY 
CAPILLARITY AND EVAPORATION 
The system of irrigation generally practiced is sub-irrigation, 
in which the water-plane is brought within a few inches of the 
surface, from 22 to 12 inches. River-water is used for this purpose 
but it effects the bringing of this “black alkali” to the surface by 
capillarity and evaporation. The fact that it is possible to main¬ 
tain the level of the water so near the surface shows that for some 
reason or other the water does not run down through the soil to 
any great depth, but is held near the surface, either because the 
lower part of the soil is so full of water that the irrigating water 
applied simply lies on top of the previous water-table, or that the 
lower portion of the soil won’t let the water run through. The fact 
is. that, in this portion of the valley, the water-plane is generally 
high; I found it 36 or 37 inches below the surface, but it can be 
