USE OF WATER BY SPRING WHEAT ON GREAT PLAIN'S. 



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, N. 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, N. 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 



20r 



/s 



s46/£(/3T 



Fig. 2. — Diagram showing the 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. T|he 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 



