COLORADO IRRIGATION WATERS AND THEIR CHANGES. 2J 
equivalent of only 12.5 pounds. This last quantity is high in 
proportion to the amount of mineral matter added, owing to the 
higher percentage of potash present in the total solids. 
§ 49. The sanitary analyses show that the changes suffered 
while the water is stored do not, in their total results, materially 
affect the quality of the water, the albuminoidal ammonia, and 
in one instance the nitrites, alone showing material changes. 
They also show that the amount of nitrogen added in all forms is 
utterly insignificant—less than four pounds per acre in the most 
favorable instance. 
§ 50. We see that the amount of plant food distributed by 
means of the irrigation water, whether it be stored water or such 
as is used directly from the river, is not so great as might have 
been expected, but its effect, if the potash present is really avail¬ 
able for the use of plants, would undoubtedly aid materially in 
maintaining the fertility of the soil. In the case of the stored 
water the potash applied in the course of four years would amount 
to a dressing of 800 pounds of kainit. 
§ 51. There is another question, i. e., how much do we add 
of other salts which are useless and may be deleterious? To this 
suggestion the answer is that, taking the aggregate results of the 
four reservoirs, as we did in the case of the potash when we found 
that the equivalent of 50 pounds of sulfate of potash per acre was 
added yearly, we find that with this amount of potash there is 
added 3.49 tons, 6,980 pounds, of other salts. This result seems 
large, but if we calculate the amount of salts added per acre when 
two feet of Windsor or Terry lake water is applied, we shall find 
still larger quantities. Windsor lake is the largest of the four and 
is intermediate as to the amount of salts held in solution between 
Terry lake and the others, and we will for this reason analyze the 
results obtained from the examination of its water. The capacity 
of the lake is 14,000 acre-feet, and its water holds in solution 
18,894.15 tons of total solids. An application of two feet of water 
per acre will distribute this over 7,000 acres, or 2.7 tons or 5,400 
pounds per acre. The potash contained in this is equivalent to 
53.6 pounds of sulfate of potash per acre. The calcic sulfate 
amounts to 1,738 pounds; inagnesic sulfate, 2,000 pounds; sodic 
sulfate, 542 pounds; sodic carbonate, 250 pounds; sodic chlorid, 
salt, 174 pounds; other substances, 330 pounds. 
§ 52. A like application of Terry lake water would add to 
each acre: potash equivalent to 54.5 pounds of sulfate of potash; 
2,604 pounds calcic sulfate; 4,718 pounds of magnesic sulfate; 
3,162 pounds of sodic sulphate and 919 pounds of sodic carbonate. 
§ 53. The above figures are for anhydrous salts, but they are 
doubtlessly present in the hydrated condition, and if calculated as 
such would be represented bv large numbers. 
