26 
BULLETIN 82. 
lake, 1,756.02 tons. To the average person, these figures convey 
but an inadequate idea of the amount of salts dissolved by these 
lake waters. If we put it, as is sometimes done, in terms of the 
transportation facilities which would be necessary to move this 
combined amount, it may give a clearer notion of the quantity of 
salts moved by these two lakes. The amount of salts carried out by 
the annual emptying of these lakes is 46,021 tons, which would 
require 1,534 cars each holding thirty tons, which, allowing 35 
feet as the length of a car, would represent a train ten miles long, 
not including engines. 
THE FERTILIZING VALUE OF THESE SALTS. 
§ 47. As the water whose composition we have so far pre¬ 
sented is used for irrigating purposes, it may not be amiss to dis¬ 
cuss the fertilizing value as it is indicated by the various analyses. 
The only constituent in the ordinary chemical analysis which is 
of importance in this respect is the potassic oxid. Our soils con¬ 
tain lime enough to meet the requirements of all cultivated crops. 
The advisability of adding lime because of its chemical action on 
the soil is left entirely out of the question, and if it were consid¬ 
ered, the form in which the lime is present in the waters would ren¬ 
der it of little value, except in a very limited range of cases. We 
will then simply endeavor to find how much potash these waters 
would add to the soil if the whole of it were retained and were avail¬ 
able to plants as food. These assumptions are made for convenience 
of presentation only, and for the same reason we will make no 
distinction between the waters of the different reservoirs, but will 
take them in the aggregate. 
§ 48. The capacity of the four reservoirs is 27,672 acre-feet. 
Allowing two feet per acre, they would together irrigate 13,836 
acres of land. The aggregate amount of potassic oxid found in 
them was 188.06 tons, equivalent to 347.9 tons of sulfate of potash, 
which would give almost exactly 50 pounds of sulfate of potash 
per acre irrigated, equivalent to a dressing of 200 pounds of the 
average kainit of commerce. It will be recalled that the percent¬ 
age of potash found in the waters was not uniform, that from War¬ 
ren’s lake yielding the highest. It will also be recalled that the 
Poudre water as taken from the river to fill these lakes furnishes an 
insignificant part of this potash; therefore, it is evident that the 
main supply must have come from seepage. Long pond and War¬ 
ren’s lake receive less seepage than the other two, and when we 
calculate the amount of sulfate of potash which their waters add 
to the soil irrigated with it, as we have for the four taken to¬ 
gether, we find that an acre receives the equivalent of only 31 
pounds, instead of 50 pounds; and if we should use water directly 
from the river, as it comes through the canyon, it would add the 
