96 
Colorado Experiment Station 
this bulletin. The samples grown with the application of nitrogen are 
again left out of consideration. The total nitrogen in the stems and 
leaves remained fairly constant till the end of July, when they showed a 
very decided decrease, in spite of the fact that the plants were drying 
out, amounting to from approximately 30 percent to 50 percent. On the 
other hand, the total nitrogen in the heads ran fairly constant till the 
end of July, when it suddenly increased from an average of 0.6967 to 
0.9868 percent, practically 0.3 of i percent in five days (29 July to 4 
August) and the head at that time was rapidly increasing in weight. 
There must have been a very active movement of nitrogen from the 
plant to the seed at that time. The wheat was cut on 6 and 7 August 
when it was fully ripe. This wheat averages 12.58 percent protein 
(Nx5.7)- 
Low Nitrogen Content In 1915 Due to Rainfall Causing Leaching or Im¬ 
pairing Transpiration 
It was impossible for us to repeat this portion of our study in 
1914 but we were fortunately able to take it up again in 1915. The full 
record of this work is given in Bulletin 217. The plants were from 
10 tO' 14 days later in their development and were more succulent than 
in 1913. The succulency of the plant was probably due to the frequent 
light rains and heavy dews. The plants are poorer in nitrogen irre¬ 
spective of the fertilizer applied, even after allowance has been made 
for the greater quantity of water in the plant. This might be due to 
three causes, exhaustion of the soil, leaching due tO' the almost continu¬ 
ously wet condition of the plant, or to a greatly retarded transpiration. 
Inasmuch as this difference is as great in the case of the plants that 
were grown with a'continuous, artificial supply of nitrogen as in those 
which were grown without any, it is probably not due to deficiency in 
nitrogen, and if there be no other causes than those suggested, it must 
be due either to leaching or to impaired transpiration. This is, in 
either case, an effect of the weather. The samples of stems and leaves 
taken from the same set of plots on 29 July, 1913, and 30 July, 1915, 
were quite close to one another in their nitrogen content, but this was 
not true of the heads which in 1915 were materially lower than in 1913* 
It is evident that in both years about this time a very active transfer¬ 
ence of nitrogen from the plant to the head began. On 27 July, 1915, 
the heads on the Fife check plot contained 0.5247 percent and on 30 
July, 0.6324 percent nitrogen. The drying out of these plants had not 
yet begun to take place. At about this time in both 1914 and 1915 the 
wheat became very rusty, but the wheat in 1914 was more advanced, 
by 5 or 6 days, than in 1915. In fact, we had had up to this time a very 
favorable season in 1914. This date is the turning point in the char¬ 
acter of our respective crops. In 1913 the nitrogen in the plants de- 
