Jan. 13, 1923 
Effect of Inorganic Nitrogen on Wheat 
67 
ASH AND SILICA CONTENT IN THE STRAW 
As seen from Table VIII, the application of nitrogen at the first and 
second stages caused a distinct depression in the ash and silica content 
of the straw. 
A depression in the silica content of the straw, caused by the appli¬ 
cation of sodium nitrate, was also observed by Headden. 12 In his case 
the depression was slight. In the bureau’s experiments the difference 
between the first two stages and the third stage, for each nitrogen 
carrier, was always more than 1 per cent. The third stage plots, not 
being affected by the application of nitrogen with reference to the silica 
content of the straw, may be considered as controls. The sharper 
differences are due probably to the exceptionally high silica content of 
the straw in this experiment. Ammonia is the exception. It did not 
depress the silica content in either series. Attention is called to the fact 
that the same chemical also failed to produce a depression in the phos¬ 
phoric-acid content of the grain. The relationship between the phos¬ 
phoric-acid depression and the depression of silica in the straw is further 
accentuated by the fact that ammonium nitrate, which failed to depress 
the phosphoric acid in the grain from the second stage plot in series A, 
also failed to depress the silica content of the straw from the same plot. 
No explanation of the theoretical principles involved in depression of 
silica can be offered at present. 
As to the bearing of this depressed silica content in the straw on 
lodging, frequently caused by the application of nitrogen, it is hard to 
draw conclusions from the present experiment. No lodging was observed 
on any of the experimental plots. It is possible that as the silica content 
of the straw in this experiment was exceptionally high, even the depressed 
silica content was sufficient to sustain the strength of the stalk. It is 
probable also that the depressed silica content is only one of the factors 
which cause lodging, or it may be no factor but only coincident with the 
real factors resulting from the application of nitrogen, which, under 
certain conditions, cause lodging of the crop. 
SUMMARY 
(1) The application of nitrogen in any of the inorganic forms used 
at tlie early stages of growth was instrumental in producing the highest 
yields of wheat. 
(2) The application of nitrogen in any of the inorganic forms used at 
the time of heading was instrumental in producing the best quality of 
grain with reference to “yellow-berry” and the protein content. It also 
produced a high protein content in the straw. 
(3) No relation between the nitrogen content and the weight per 1,000 
kernels and weight per bushel of wheat was disclosed in this experiment. 
The apparent disagreement between these results and the results of other 
experiments, which establish a relation between these two factors, is 
explained by the distinction between a physical abundance and a phys¬ 
iological abundance of nitrogen created by the failure of the crop to 
develop normally. 
(4) No differences could be observed in the effect of the different 
forms of inorganic nitrogen. 
12 Headden, W. P. op. ax. 
