WATER UTILIZATION BY SPRING WHEAT. 7 
there have been only a few moisture determinations that have been 
considered as not providing a true indication of the moisture content 
of the plat. 
The object of this study is not to determine the exact quantity of 
water used from each foot section of soil each year, but rather to 
determine the extent to which the moisture-storage capacity of the 
soil has been utilized and the extent to which the stored water has 
been removed at harvest. 
The moisture content of each foot of soil of each plat at every 
determination during the season has been charted. By a study of 
the diagram it can be determined quickly and with a considerable 
degree of accuracy whether available moisture has been present in 
any foot of soil during the growing season and whether the avail- 
able moisture in any foot of soil has been removed. 
Figure 1 shows the moisture content of each individual foot of 
plat B at Williston, N. Dak., in 1910. The successive determina- 
tions of the moisture content of each foot have been connected by 
lines. The resulting curves give a good history of the moisture con- 
tent of each foot of soil for the season ; the dotted lines represent the 
wilting coefficients of the several foot sections. 
The soil in the first foot at the time of the initial determination 
was at its field carrying capacity. This moisture content was not 
maintained by rainfall, and by harvest, July 26, the moisture of the 
first foot had been reduced to the minimum point of exhaustion. The 
second foot of soil possessed only a small quantity of available 
moisture, and this supply was exhausted long before harvest. There 
is no evidence to indicate that any available moisture was present 
below the second foot, and results from other plats and from 
this plat in other years show that it was dry as far as water avail- 
able to crops is concerned. A point worthy of note is the fact that 
the minimum point of exhaustion of the soil in the lower depths 
more nearly approximates the wilting coefficient than in the upper 
depths. The greater experimental error in the fifth-foot and sixth- 
foot depths is indicated by the broken curves of those sections. The 
fact that the crop suffered severely for lack of water was noted 
several weeks before harvest. The extent of drought injury is in- 
dicated by the low yield of 1.3 bushels per acre. 
The depth to which the crop used water that year was less than . 
2 feet. The storage capacity of the first foot of soil was all utilized 
and that of the second foot only partly utilized. 
CLASSIFICATION OF DATA. 
The presence of available moisture in the soil each year and the 
extent to which the moisture present has been used are divided into 
five classes, which are indicated by symbols. These symbols are 
designed to show at a glance the moisture history of any foot section 
of soil for a season. The condition represented by each symbol is 
as follows : 
(1) A condition where the soil has been filled with water to its field carry- 
ing capacity at some time during the growing season and where all of the 
