A Study of Colorado Wheat 
45 
recalled that it is shown in Part I, p. 42, that 93 percent of the total 
soluble ash in the air-dried wheat plant can be extracted with wate.r. 
The size of the plants and the percentage of dry matter in them was 
not materially different in the two seasons. 
The part played by the greater cloudiness and a lower mean 
temperatu.re in 1915 than in 1913 has not been made out. It is for 
this reason that I refer to effects that seem attributable to water, or 
its manner of application in 1915. At the present time, I entertain 
almost no doubt but that these effects are due to the external ap¬ 
plication of the watey to the plants, or to their having been kept 
wet for so large a portion of their growing period. There are but 
two other things that I see, in addition to the cloudiness and mean 
temperature, that may militate against this view, and they are, the 
extent to which a living plant may diffe.r from a dead one in the sol¬ 
ubility of its constituents, and the possibility that transpiration was 
reta.rded to a sufficient extent to have reduced the intake of ni¬ 
tric acid and the non-volatile ash constituents. 
The very different weather conditions which prevailed during 
the two seasons were in .reality very fortunate for us, for they serv¬ 
ed to demonstrate the fact that the observed effects of the fertliiz- 
ers applied in 1913 are independent of the weather. The weather 
conditions of 1915 made great differences in both the nitrogen com¬ 
pounds and ash constituents of the plants, but they did not obscure 
the effects of the nitrate applied upon the total or the proteid ni¬ 
trogen or the silicon or the ash constituents in general. The same 
is true in regard to the effects of the phosphorus and the potassium. 
The effects of the application of nitrogen was to increase the 
nitrogen in all parts of the plant; this was iinifo.rinly true in the 
stems, leaves and heads, for both the total and proteid nitiogen. 
and as positive in the wet season as in the dry one. It increased it 
in the stems and leaves and less regularly so in the heads. It low¬ 
ered the percentage of dry matte.r; it lowered the percentage of 
silicon; it increased the percentage of potassium, calcium and mag¬ 
nesium as a rule, and increased the total ash, while it exerted no 
influence upon the amount of phosphorus in the plant. It increased 
the height of the plant, the length of the head, and the color of the 
plant, but it did not increase the kernels per spikelet. 
Phosphorus seemed to be either indifferent to, or possibly tend 
ed to depress, the amoiint of nitrogen in the different parts of the 
plant. The same is true of potassium, with a stronger tendency to 
dep.ress the nitrogen. 
Both phosphorus and potassium depressed the phosphorus in 
the plant. This is true of these elements except in one case, in 1913, 
in which the plants grown with the application of potassium, con¬ 
tained more phosphorus than those grown on the check plot. 
