A Study of Colorado Wheat 
97 
creased regularly till the wheat was ripe. The stems and leaves dried 
out and the dry matter increased very greatly, but it was poorer in 
nitrogen than the plant had been at an earlier date. The heads increas¬ 
ed in weight and dry matter, but most of all in nitrogen. On 25 July 
the heads of plants from plots which had received no dressing of nitro¬ 
gen contained 0.8495 ^.nd the heads of plants from the same plots on 5 
August contained 1.2463 percent of nitrogen. Samples taken from 
other plots between these dates indicate that practically the whole of 
this change took place between 29 July and 4 August. This wheat was 
free from rust, ripened naturally and was cut on 6 and 7 August. The 
average protein content of the samples of this variety grown without 
the application of nitrogen was 13.63 percent (NX5.7). 
I have pointed out that on 30 July the plants of the' 1915 crops 
contained approximately the same amount of nitrogen as in 1913. 
From this date till that of full ripeness of the grain, the crops acted 
entirely differently. There was some increase in the nitrogen of the 
heads, but it was in no measure comparable to the change that took 
place in 1913* On 30 July the heads from a check plot averaged 0.6486, 
on 12 August heads from the same plot averaged 0.7828 percent nitro¬ 
gen. During ii days in 1913 we found that the nitrogen in the heads 
increased from 0.85 to 1.25 percent; in 1915 we found that they in¬ 
creased from 0.65 to 0.78. This apparent increase itself is doubtful 
when we consider the drying out which took place. On the other hand, 
we found that the stems and leaves did not diminish in their nitrogen 
content from this date on till that of ripeness as in 1913. On 6 August, 
the earliest date on which the leaves and stems were taken together, 
the average nitrogen content of the plants grown without the applica¬ 
tion of nitrogen was 0.2371 percent and that of the heads 0-6834 
cent; on 12 August the plants and leaves contained an average of 
0.2703 and the heads 0.7825 percent. The increase in the heads is at 
best very small, and, owing to the drying out and relative increase in 
dry matter, is a little doubtful. This wheat was harvested 16 August 
in good condition, except for the rust. The average protein content 
of this wheat was 8.41 percent. This average is 5.22 percent below that 
for the season 1913. 
Rust Was Severe In 1915 
We unfortunately were not able'to follow this feature of our 
study in 1914. We can, however, record the fact that we had very 
favorable conditions up to the end of July, when we had a heavy show¬ 
er which beat down our grain and rust followed. The grain was more 
advanced in its development when this happened than it was in 1915 
when the rust attacked it. We do not know that the nitrogen transfer 
was practically stopped in 1914 as it was in 1915. The effect, how¬ 
ever, on the composition of the wheat was almost the same. The aver- 
