14 



BULLETIN" 1004, U. S. DEPARTMENT OE AGRICULTURE. 



keep the crop growing rapidly. However, the early drought checked 

 the growth of straw, and the crop, by reason of its meager straw 

 growth, was able to maintain life until harvest on the rains that fell 

 and to mature a small yield of grain. This condition is indicated 

 by the curve (Fig. 2), which shows a comparatively low rate of use 

 throughout the season. 



The use of water by the plat of wheat grown on fallowed ground 

 at Dickinson in the years 1909, 1910, and 1911 is shown in Figure 3. 

 It will be noted that the 1909 curve for this plat is practically the 

 same as the one for plat A shown in Figure 2. The curve follows 

 the same general line and there is the same long-continued use of 

 water and resulting high yield. The actual date of harvest was sev- 

 eral days later than for plat A, but the final soil-moisture determina- 

 tion was made on the same date on both plats. In both 1910 and 

 1911 the water use was continued at a rapid rate practically until 



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Fig, 3. — Diagram showing the use of water by the wheat crop on plat C or D at 

 Dickinson, N. Dak., for the years 1909, 1910, and 1911. 



harvest. This plat ripened a little prematurely in both years on 

 account, of drought, and both years show a shorter rapid- growth 

 period and a lower yield than in 1909. 



The most . noticeable difference between the two charts is in the 

 behavior of plat C or D and plat A in 1911. Plat A suffered for 

 water at nearly all times during the season and was able to mature 

 only a small yield of grain. Plat C or D, by reason of the water 

 stored in the soil through fallowing the previous year, was able to 

 make a good growth and mature a good yield of wheat. It conse- 

 quently shows a much higher rate of use of water than plat A 

 throughout the season. 



Figure 4 shows the use of water on plat A at Akron, Colo., for the 

 years 1909, 1911, 1912, and 1913. Two of these. 1909 and 1912, were 

 good years for wheat. In 1909 the wheat was planted late and did 



