A Study ot Colorado Whlat 
5 
food of primary importance to us is the nitrogen. This is also the con¬ 
clusion to which our experiments lead. 
Availability, Not Quantity, Affects Grain 
Our soils are only moderately well supplied with total nitrogen. 
The one on which our experiments were made carried about 0.145 
percent. This is neither poor nor especially rich, still it is sufficiently 
available to produce, under ordinary tillage, abundant crops of wheat, 
30 to 48 bushels, without the application of any kind of fertilizer. 
These results were obtained with wheat following wheat. The total 
amount of nitrogen present is not so abundant or necessarily of such 
a character as to assure us of a continued abundant supply of available 
nitrogen, and yet for five years in succession we have detected, so far 
as the crop indicated, no lack of nitrogen, while the addition of 10 lbs. 
of nitrogen in the form of sodic nitrate to a milion pounds of soil has 
not failed to change the character of the wheat produced without in¬ 
creasing the crop, except in a few instances and then only slightly. 
We can interpret these facts in only one way and that is that it is not 
the amount of total nitrogen but the amount present in an available 
form, in this case as nitrates, that is important. If the crop in our 
experiments had been increased and the character not changed the only 
inference that we could have drawn would have been that there was 
not enough of this form of nitrogen present in the soil to produce the 
best crop and its addition for this purpose would be advisable. This 
was not the case, but, the reverse. The size of the crop was not fav^ 
orably afifected but the quality of the crop was, which we have in¬ 
terpreted as proof that the supply of nitrogen in this form was suffi¬ 
cient to produce a maximum crop but not sufficient to produce a 
maximum quality. 
It may be a c[uestion in the minds of some whether we have a suffi¬ 
cient basis for making the statement without any qualifications, that 
the results obtained were specifically due to the form in which the 
nitrogen was applied. The fact that we obtained this result more than 
50 times without any exception when we applied the nitrogen in this 
form does not prove that organic nitrogen would not have produced 
the same results though it does prove that the results observed are 
uniformly the effects produced by nitrogen in the form of nitrates 
when present in sufficient quantities. In our soil the addition of 10 
pounds of nitrogen in this form to 1,000,000 pounds of soil is really too 
much, for in many instances there was no question about our having 
done injury. We have experiments in which we added nitrogen in 
the form of farmyard manure at the rate of at least 120 pounds of 
nitrogen to a million pounds of the soil or 12 times the amount added in 
the form of nitrates and it produced no effect upon the composition or 
