6 
Colorado Experiment Station 
average one, but not enough so to cause comment. This was not the 
case with the season of 1915, which the consensus of opinion would 
unhesitatingly designate as a bad year for wheat, a wholly abnor¬ 
mal year. Mr. Robert Trimble, in charge of our meteorological ob¬ 
servations, has furnished me the data for the months of April, May, 
June, July and August of the respective years, which show the dif¬ 
ferences between the seasons in so far as may be done by figures. 
The total rainfall during these months in 1913 was 6.77 inches, and 
in 1915, 13.37 inches. In 1913 we had only four wholly cloudy days 
during these months, while in 1915 we had only 57 days free enough 
from clouds to justify the designation of clear. In the following 
statements of mean temperatures that for 1913 is given first, and 
then that for 1915. April, 46.1°, 50.05° ; May, 54.8°, 50.35° ; June, 
63.2°, 59.62°; July, 66.8°, 64.74°; August, 69.8°, 62.77°. The rain¬ 
fall in 1915 was not only unusual, but it was distributed through 
the season so that the plants were kept wet most of the time, 
the prevalent cloudiness preventing a thorough external drying, 
even when theye was no actual rainfall. 
This proved to be very prejudicial, not only to my crop, but 
locally to all of our spring wheat, especially to our popular variety, 
the Defiance, because of the severe attack of rust which was induced 
by these conditions. 
In 1913 I applied to my plots one acre-foot of water on 12 June 
and to four of them a second acre-foot on 12 July. Thirty-two of 
the plots received, as irrigating water and rainfall, practically 19 
inches of water during the growing season, 12 inches of which was 
applied at one time and in clear weather. Three and one-half inches 
of the 6.8 inches of rain fell in April and May, and 2.5 inches be¬ 
tween 13 and 24 July. This last period of rainfall caused some rust 
I to develop. The subsequent -fourteen days were dry and bright, and 
the damage was not serious. In 1915 the plots received from 0.5 to 0.6 
of an acre-foot of irrigation water, this being all that was required to 
flood the land. It will be noticed that the amount of water received 
during the two seasons was very nearly the same. In 1915 the amount 
of rainfall was not only greater, but its distribution was different and 
accompanied by a great deal of cloudiness. These conditions af¬ 
fected not only the rate of the development of the plants and of the 
rust, but modified our conditions of soil moisture, the distribution 
of the nitrates, and probably also affected their formation, as well 
as the amount of fixation that took place. These last two factors 
are, unfortunately, not definitely known nor are they easily ascer¬ 
tained. 
The general conditions as here described may seem to be unfor¬ 
tunate. As matters stand they really are, but were it not for the 
introduction of the factor of rust, I would be inclined to consider it 
