A STUDY OF COLORADO WHEAT 
I 
By VV. P. HEADDEN 
PART III 
In the preceding portions of this work I "have shown* that the 
moisture which we determined at short intervals throughout the two 
seasons varied but little. These intervals were not all equal, but varied 
according to the weather or the application of water, irrigation. For 
the actual variation of this factor reference may be had to Bulletins 
208 and 217. The moisture in the soil during the two seasons was not 
far from 15 percent. The plants did not, at any time, show the need 
of more water than was at their disposal. 
The total nitrogen in the soil is given for a rather large number 
of samples of the surface soil, for the top four feet, and also for the 
top eleven feet. The surface portion varies considerably in the arnount 
of total nitrogen present in it. The total nitrogen in 150 samples, 
laken at the same time and from a space 5 by 30 feet, varied from. 
o.'iioi6 to 0.14552 percent. We have here a difference of 0.0354 per¬ 
cent of nitrogen. This variation involves an amount of nitrogen many 
times greater than that which, in the) form of sodic nitrate, is neces7 
sary to produce most positive effects upon the growth and composi¬ 
tion of the plant. The application of nitric nitrogen equivalent to 
0.001 percent, or lo parts per million is, in our case, sufficient to cause 
the grain to lodge, to change the physical propefties of the kernels, also 
to increase the nitrogen in both the plant and kernel, and to affect the 
amounts of the various ash constituents appropriated. 
THE FIXATION OF NITROGEN IN SOILS USED 
In regard to the fixation of nitrogen by this soil, I have so far 
relied upon laboratory experiments, because the variation in the nitro¬ 
gen content of field samples on a given date is greater ‘than the 
amounts involved in the question of fixation itself. In the case just 
mentioned, we had a difference of 354 pa-rts per million, and this dif¬ 
ference was found on contiguous areas of i square foot each. The 
largest actual increase in the total nitrogen observed in this soil to 
which nothing but boile^l distilled water had been added, was 105 
parts per million; stated otherwise, samples gathered from the field on 
different dates cannot be relied on to either prove or disprove the fact 
