Colorado Experiment Station 
i6 
was equal to 263.2 and 91.6 pounds, respectively. 
Lyon and Bizzell of Cornell University have shown that the ni¬ 
trifying efficiency of soil occupied by wheat is depressed, and this 
may account for a part- of the difference.'^' But the results, taken 
as they stand, show a very decided difference between the fallow 
ground and that occupied by the plants. An examination of the 
160 series of samples taken shows this to be uniformly the case, but 
in varying degrees. 
This suppression of the nitrates, be it due to the utilization of 
the nitric nitrogen or the suppression of the nitrifying efficiency of 
the soil or to both, is certainly only a temporary result, for as soon 
as the wheat has ripened, the production of nitrates goes on rapid¬ 
ly, as the following results summarized from the data previously 
given shows. The equivalent sodic nitrate is given for the four 
feet sampled: 
TOTAL SODIC NITRATE, 
FOUR-FOOT 
SECTIONS OF 
SOILt 
1913 
1915 
Section 
Section 
Section 
Section 
1800 
1900 
1800 
1900 
12 May 
Fife 
4.59.7 
340.6 
440.4 
489.6 
1 Aug. 
Fife 
114.0 
107.8 
91.9 
51.7 
30 Aug. 
. Fife 
* * . . 
.... 
102.7 
80.3 
22 Nov. 
Fife 
• • • • 
.... 
179.0 
136.3 
13 May 
Kubanka 
333.2 
213.3 
465.8 
485.0 
1 Aug. 
Kubanka 
155.9 
81.4 
51.4 
38.9 
30 Aug. 
Kubanka 
102.2 
112.1 
22 Nov. 
Kubanka 
.... 
.... 
154.3 
191.6 
t The results have been calculated as sodic nitrate. 
The plants had not developed enough by 12 May in either year 
to make much difference betwen these plots and fallow ground. 
The figures given for 1 August, however, are really not altogether 
comparable, because in 1913 the plants were practically ripe on this 
date, but were two weeks later in 1915, so that the data for 30 Au¬ 
gust, 1915, are much more nearly comparable with those of 1 Au¬ 
gust, 1913, than are those of 1 August, 1915. Tn either case we see 
that a very large amount of nitrogen has disappeared. The irri¬ 
gation may have washed out a large percentage of it, as we found 
in 1913 that the application of one foot of water sufficed to remove 
the larger part of the nitrates to a greater depth than 12 feet. That 
the irrigation did not make the difference in 1915 is indicated by 
the results obtained on a fallow ]dot used as a check. (See the 
tables for IcS June and 8 July.) The land was irrigated 12 June, 
but owing to the already abundant supply of moisture in the soil, 
this plot received only 0.60 of an acre-foot, which did not suffice to 
do much if any leaching. We are forced. T think, to attribute the 
depression of the nitrates to the action of the ])lants, either by inhib¬ 
iting the formation of the nitrates or by using them up. The wheat 
* Journal .'-i tlie 1 laiikhn Itistitute. Jan. and Feb. 1911, p. 220. 
