USE OF WATER BY SPRIXG WHEAT ON GREAT PLAINS. 
13 
In the same manner the water used from the first sampling until 
each date is indicated. The points are then connected by a line. 
The slope of the line between successive points shows the rate of use 
during the period it covers. 
The use of water by more than 100 wheat crops has been deter- 
mined and charted. It is not considered necessary to reproduce all 
these charts. A sufficient number will be reproduced to show the 
types of curves representing different seasons and localities. This 
purpose is adequately served by charts showing the water use at 
Dickinson, X. Dak., Akron. Colo., and Amarillo, Tex. These sta- 
tions are representative of the northern, central, and southern 
sections of the Great Plains. 
The use of water at Dickinson, X. Dak., for the years 1909, 1910, 
and 1911 on plat A. a spring-plowed plat cropped continuously to 
wheat, is shown in Figure 2. The year 1909 was exceptionally favor- 
able to wheat. There was no time during the season when the crop 
20 
/s 
Fig. 2. — Diagram showing tlae use of water by the wheat crop on plat A at Dickinson, 
N. Dak., for the years 1909, 1910, and 1911. 
suffered for lack of water. As a result, it made a good growth and 
continued to use water at a rapid rate for a long time. The rate of 
the use of water from about June 1 to harvest is nearly constant. 
The year 1910 was not so favorable. The wheat crop commenced to 
use water rapidly, but the water supply began to run short early 
in July. The rain in July was sufficient to keep the crop from being 
badly damaged by lack of water, but there was some suffering that 
was reflected partly in a slightly lower rate of use near harvest but 
more particularly in a forced ripening of the crop and an early date 
of harvest. The year 1911 was one in which the crop suffered for 
lack of water or lacked sufficient water to make much growth during 
practically all of its growing season. Except for a short time in 
the early part of June, there was not enough moisture in the soil to 
