46 
Colorado Experiment Station 
basin is a case by itself but is similar to the others. In such 
basins the shallow wells yield bad water. It was such a weU 
that caused the death of the 17 head of cattle. At this place a 
«leep well, 280 feet deep, yields water free from nitrates. It is 
not every depression within this area that yields nitrates. A 
little to the south, half a mile, and about 1 mile west, we find a 
]>lace with water on the surface of the ground (I do not know 
that this is true the year round) with a well at the edge of this 
pond. Neither the well nor pond- water shows the presence of 
nitrates. The well-water was said to be bad for stock. 
Perhaps 3 wells in Secs. 6 and 7, T. 7 N. R. 67 W. show the 
relation of the characters of the water and the surface soil bet- 
ter than these in which the' nitrates are so abundant. In these 
cases the soil is richer in nitric nitrogen than normal, 52.0, 
59.0, 60.0 and 191.0 p.p.m. and the well waters at these places 
carry 56.5, 63.0 and 57.4 p.p.m. of nitric nitrogen, whereas the 
neighboring wells carry 1.5, 1.2, 3.5, 3.0, 0.6 p.p.m. and two deep 
wells in the next section carry none and 8.0 p.p.m., respectively. 
I know that objection may be made to the adequacy of this 
proof but it appears to me that no successful denial can be made 
of the conclusion that the surface soil is the source from whicli 
these nitrates are derived, as the wells are from 18 to 25 fed. 
deep. 
FOUR EXCEPTIONAL WELLS 
I have met with but 4 cases in which 1 had any doubt at all 
about the nitrates having been derived from the surface soil, 
above and surrounding them. These four were widely separated 
from one another; two of them were in the Arkansas Valley and 
two in the area discussed in this bulletin. 
The two instances in the Arkansas Valley were callcfl to m v 
attention by the cor*respondence of the owners. 1 we^'t^ to see 
these wells but one of them had been filled ii]>. The other well 
was 27 feet dee]). The water (airrying zone was one foot 
thick and began at a depth of 23 feet. No water came in below 
the 24th foot. This was in a dry-land section and there was no 
canal or other water very near to it. The last time that I visited 
this well it was dry. There was no other water found on this 
ranch, though one well was dug to a depth of 28 feet and an- 
other to a depth of 50 feet, which developed a ])oclvet of good 
water that was soon exhausted. The nitrates present in this 
water, calculated as sodic nitrate, amounted to 5,440.0 p.ii.m. I 
find that in writing of this in 1911, ( Pnlletin ITS, ]). 7o.) I said 
^^The source of the nitrates contained in this water is unques- 
tionably, I think, the higher lying surface soil 1o (lie norlh of 
