A Study of Colorado Wheat 
25 
of the season as shown by the weight of the threshed grain. How 
much of this result is to be attributed to the effect of rust and how 
much to that of the nitrate itself, is not clear, besides, these two 
questions cannot be judged separately, for it was evident that the 
nitrate plots suffered more from rust than the other plots. This fact 
we attributed to the effect of the nitrate upon the condition of the 
plant, not simply because it was lodged, but also because the nitrate 
had rendered it a better plant for the rust to grow on. One effect 
of nitrate has been stated in a previous bulletin to be the bringing 
about of an abnormal ripening, even when the weather conditions 
are favorable to a normal-ripening of the crop, and the quantity of 
nitrate is not sufficient to cause lodging. 
THE DRY MATTER IN THE PLANTS OF 1915 CROP 
The inference from the preceding discussion would be that the 
plants grown with nitrate were heavy in stems and leaves because 
they were bigger and not because they contained more water. This 
latter, however, was the case. The samples for 1913 showed this to 
be the case in every set of samples in comparison with plants grown 
with the application of phosphorus and potassium, which were 
either essentially equal to or less than those grown on the check 
plots. This excess of water tends to make the dry weight of the 
plants more nearly equal. The following table shows that the rule 
is that the plants grown on the plots which received potassium or 
phosphorus are the richest in dry matter, irrespective of variety, 
though the plants grown on the check plots are almost as rich, some¬ 
times even richer in dry matter than those grown with phosphorus 
or potassium. The plants grown with the application of nitrates 
are, almost without exception, the poorest in dry matter, irrespect¬ 
ive of the variety or the amount of nitrate applied. These obser¬ 
vations are applicable to the samples of both seasons, 1913 and 1915, 
but the samples of the two seasons cannot be compared date by date, 
for the development of the plants in 1915 was retarded from 6 to 14 
days, owing, I take it, to the weather conditions. This difference in 
the development of the plant increased with the season and the max¬ 
imum difference was at the time of ripening. The ripening period 
was greatly influenced by the appearance of rust, which practically 
killed some of the Defiance. 
