WATER UTILIZATION BY SPRING WHEAT. 17 
fleeted in the yield. All available water has been removed from 
all foot sections of soil in all years under study. 
The soil at Scottsbluff is sandy in character. It is easily penetrated 
by water in the upper depths, but evidently becomes increasingly 
difficult of penetration in the lower depths. Plat B has never had 
available water present below a depth of 4 feet, and plat A only 
once. The maximum depth of penetration of plat C or D has been 
6 feet, and this depth has been reached but once. On this soil all 
available water has been removed from all plats each year. Plats 
A and B have exhibited only minor differences in the extent to 
which they have utilized the storage capacity of the soil. Plat C 
or D has been superior to the others in water stored and in yield. 
The soil is evidently porous enough to allow root development suffi- 
cient to remove all moisture penetrating into it under ordinary con- 
ditions. 
The soil at North Platte is probably the most uniform of any at 
these stations on the Plains. It is open and porous and offers a 
maximum opportunity for penetration of water and roots. The 
precipitation at this station has been high enough at different times 
to wet the soil thoroughly to a depth greater than 6 feet. Determi- 
nations of soil moisture to a depth of 15 feet have been made at 
this station, but spring wheat has shown no evidence of feeding to 
a depth greater than 6 feet. The station record comprises about 
an equal number of good and poor years. The fact that roots will 
not penetrate a dry layer of soil to obtain water in moist lower 
depths is illustrated by plat A in 1908 and by plat B in 1908, 1909, 
1911, 1917, and 1919. These two plats exhibit some differences in their 
moisture relations in individual years, but on an average they show 
about the same water storage and water utilization. Plat C or D 
has stored much more moisture than plats A and B. In all years 
except 1914 it has carried available moisture to a depth of 6 feet, 
and there is evidence that on several occasions water has penetrated 
beyond the sixth foot. This water has been lost to the wheat crop, 
as the roots of wheat do not penetrate the seventh foot section, even 
in this favorable soil. The season of 1915 at North Platte was one 
of the wettest on record at any station. All three of the plats con- 
tained as much moisture in the first foot at harvest as they had at 
any time during the growing season, and all foot sections of soil 
on all plats had available water at harvest. The use of water in the 
fifth and sixth foot sections of soil has been usual on plat C or D, 
but only on one occasion has all of the available water been used 
from these units. Plat C or D in 1911 shows the result of severe 
climatic conditions in limiting the depth of feeding. In that year 
the weather was so hot and dry and the demands of the crop for 
moisture so excessive that the crop died before it was able to extend 
its roots to the available water in the fourth, fifth, and sixth foot 
sections. 
Under natural conditions and under some conditions of cultivation 
there is considerable run-off from the soil at Akron. After water 
penetrates the surface the character of the soil does not definitely 
limit further penetration or development of the roots. Plat A has 
shown on an average a deeper water penetration than plat B. In 
