A Study of Colorado Wheat 
29 
are quite as pronounced in 1915 as in 1913, showing that, while the 
season influenced the whole problem, it did not obscure the effects 
of the nitrate. The most noted differences are shown by the samples 
of the heads as they approached ripeness. The total nitrogen in 
the heads of the last four samples, gathered 5 August, 1913, aver¬ 
aged 1.2587 percent, but in those on 9 August, 1915, from the same 
plot of ground and of the same variety of wheat, the average was 
only 0.7644 percent. A difference is shown by the earliest samples 
gathered in the respective years, but the difference is smaller, 0.1675 
against 0.4943 percent. The differences between the total nitrogen 
in the heads of the plants for the respective years increased as the 
plants matured. This was probably not due to the total supply of 
nitrogen in the soil, for, if we compare the plants grown with the ap¬ 
plication of 120 pounds of nitrogen per acre, in the form of sodic 
nitrate, at the time of full bloom, we find that the heads in 1913 
contained 0.7607 percent of nitrogen; in 1915, the same variety, 
grown on the same land, and also with the application of 120 pounds 
of nitrogen, contained 0.6324, showing a difference of 0.1283 percent, 
which is a little less than the average found for all of the plots in 
this section, i. e., 0.1675. This difference increased during the sea¬ 
son. These results, especially those obtained with mature plants, all 
involve the question of the effects produced by the abundant ap¬ 
pearance of rust. 
I have no way of estimating how great the influence of this fac¬ 
tor was, nor of conveying any definite idea of the severity of the 
attack, but it was very bad, even on Red Fife, the variety used for 
the nitrogen work, while it ruined the Defiance. The factors ap¬ 
pearing in this year’s work are the fertilizers applied, the weather 
conditions, and the effects of the rust. The same factors were op¬ 
erative in 1913 also, but they were very different, the rainfall, for 
instance, in 1913, between 18 May and 7 July, the date on which 
the first samples of plants were taken, was 0.36 inch, in 1915, for the 
same period, 18 May till 13 July, the date of taking the first sam¬ 
ple, it was 5.94 inches. In the former year we applied, on 12 June, 
one foot of water, in the latter 0.6 of a foot, also on 12 June, so 
that the amount of water received by the plots was essentially the 
same, but, in 1913 the water was applied to the land in practically 
one application, while the plants, throughout the period consid¬ 
ered, were scarcely wet at all and the weather was clear. The quan¬ 
tity of water received in 1915 was smaller by less than one inch, but 
its application and distribution were different, the plants themselves 
being kept almost continuously wet by frequent light rains, and 
cloudiness prevented their rapid drying. The mean temperature, too, 
was a little lower in 1915 than in 1913. As the differences existed 
early in the season, before the appearance of the rust, we cannot 
