A Study of Colorado Wheat 
19 
> this point, we have only to consider the results produced by the ad¬ 
dition of 40 pounds of nitrogen to the acre, an amount equal to 
0.001 percent calculated on a foot of soil. The application of this 
amount at the time of seeding, and liar,rowed in to a depth of three 
inches, suffices to change the growth of the crop and the character of 
the wheat. In determining the total nitrogen we involve all of the 
nitric nitrogen that may be present and other unstable forms to such 
an extent that the differences obtained in our analyses are difficult, 
if not impossible, of interpretation with any degree of certainty. 
We have, for instance, on 13 May, 1915, in Section 1800, Fife, a total 
of 5,305 pounds of nitrogen in the surface acre-foot; on 1 September 
in the same land cropped to wheat, 4,350, and in a check plot kept 
fallow, 4,684 pounds. We have for this land a loss of 625 pounds of 
nitrogen for the surface acre-foot between 13 May and 1 September. 
This is without the crop, but with the crop of wheat we have a fur¬ 
ther loss of 334 pounds. Some of this may have been washed below 
the depth to wdiich we took our samples and this may have been lost. 
There are too many undetermined factors at play in this question to 
permit us to interpret our results. There have been, without doubt, 
both gains and losses, some of the latter due to the crop, but just to 
what extent we do not know. It seems very improbable that the loss 
of 334 pounds of nitrogen, noted above, is due directly to the crop, 
which did not remove, as a mature crop, more than a sixth or, at 
most, a fifth of this amount. The crop of grain removed was 33 
bushels per acre and the straw weighed 4,750 pounds, which, to¬ 
gether, would not remove a fifth of this deficit, 334 pounds. The 
analytical results themselves are as good as can be gotten; this is 
not the trouble, but other difficulties inherent in the problem. 
PERCENTAGE OF TOTAL NITROGEN IN SOIL OF WHEAT PLOTS—SEASON 1915 
Section 
Section 
Section • 
Section 
Section 
Section 
Section 
1700 
1800 
1900 
1700 
1800 
1900 
1800 
Date 
Depth 
Fife 
Fife 
Fife 
Kubanka 
Kubanka 
Kubanka 
Fallow 
13 May 
Top 3 inches . 
. . . .1393 
.1279 
.1331 
.1368 
.1327 
.1373 
Not 
4 to 7 inches . 
. . . .1441 
.1403 
.1382 
.1421 
.1385 
.1439 
sampled 
8 to 12 inches 
. . . .1322 
.1293 
.1316 
.1212 
.1315 
.1328 
Same as 
13 to 24 inches 
. . . .0718 
.0645 
.0737 
.0669 
.0700 
.0711 
Section 
25 to 36 inches 
. . . .0351 
.0349 
.0477 
.0339 
.0383 
.0374 
1800 
37 to 48 inches 
. . . .0332 
.0277 
.0295 
.0289 
.0273 
.0287 
Fife 
1 Sept. 
Top 3 inches . 
. . . .1205 
.1113 
.1243 
.1198 
.1239 
.1260 
.1202 
4 to 7 inches . 
. . . .1251 
.1123 
.1208 
.1218 
.1224 
.1282 
.1226 
8 to 12 inches 
. . . .1045 
.1044 
.0984 
.1130 
.0994 
.1046 
.1108 
13 to 24 inches 
. . . .0561 
.0506 
.0578 
.0523 
.0562 
.0553 
.0551 
25 to 36 inches 
. . . .0297 
.0274 
.0332 
.0294 
.0338 
.0292 
.0295 
37 to 48 inches 
. . . .0190 
.0175 
.0214 
.0245 
.0244 
.0247 
.0224 
25 Oct. 
Top 3 inches . 
.. . .1274 
.1196 
.1241 
.1224 
.1193 
.1255 
4 to 7 inches . . 
.. . .1157 
.1263 
.1292 
.1307 
.1145 
.1108 
Not 
8 to 12 inches 
.. . .0985 
.0979 
.0901 
.0915 
.1102 
.1004 
sampled 
13 to 24 inches 
.. . .0530 
.0506 
.0549 
.0494 
.0441 
.0517 
25 to 36 inches 
.. . .0327 
.0275 
.0341 
.0305 
.0353 
.0308 
37 to 48 inches 
.. . .0240 
.0223 
.0253 
.0227 
.0233 
.0226 
