A Study of Colorado Wheat 
15 
for a few days at the critical period in the development of the wheat 
may rnin the crop. It is in this manner that moisture enters into 
our problem of producing a crop rather than as a soil problem, pro¬ 
vided that there is not at any time a decided deficiency in the soil. 
The moisture in these experimental plots for the two years 1913 
and 1915 varied from approximately 12 to 17 percent, except at peri¬ 
ods of irrigation or rainfall. 
An excessive amount of water in the soil might drown the 
plants or it might dilute the nutrients in the soil, or even wash them 
out to such an extent as to be detrimental. We have no proof in the 
data so far obtained that the latter is the case to such an extent 
that we should give it any consideration in this place. 
The distribution of the nitrates in the soil, particularly in the 
to}) two feet, is very largely determined by the water received at 
the surface. We endeavored in 1913 to follow this effect to a depth 
of 12 feet.'" 
At the end of April, we found the distribution of the nitrates 
in the soil taken to 12 feet very varying, but the nit.rates were quite 
abundant within this depth. The application of one foot of water 
at one time sufficed to move the most of the nitrates to a greater 
depth. The frequent light rains of 1915 effected a different distri¬ 
bution of the nitrates in the top two feet of the soil from that which 
we had in 1913. I do not think that this was any disadvantage to 
the 1915 crop. It may have, and probably did, change the point of 
most active feeding within this depth, but was probably without fur¬ 
ther effect. In 1913 the surface foot was markedly the richest area; 
in 1915 the nitrates were more evenlv divided between the top two 
feet. 
The total amount of the nitric nitrogen present in the four feet 
of soil sampled during the two seasons is much more nearly uniform 
than we would expect to find it. There are such variations as we 
know to prevail in different sections taken on the same date. These 
variations are often relatively large both for any given foot, and 
.also for samples representing from four to twelve feet. We have a 
few samples taken to a depth of four feet which are comparable, as 
they were taken from the same plots. On 14 July, 1913, we found 
nitric nitrogen equivalent to 260.3 pounds of sodic nitrate, and in 
another sample, 277.3 pounds; on the same date 1915, we found 
273.2 pounds per acre. 
The effect of the growing crop upon the amount of nitric ni¬ 
trogen in the soil is very clearly shown during both seasons. The 
following data are obtained from the same plot of ground fallow 
and occupied by wheat: On 14 July, 1913, nitric nitrogen in the 
top four feet of fallow ground was equal to 260.36 pounds sodic ni¬ 
trate, and in the cropped land to 120.36 pounds; on 8 July, 1915, it 
• Part I (Colorado Exp. Sta. Bulletin 208), pp. 14 and 15. 
