16 



BULLETIN 1004, U. S. DEPARTMENT OF AGRICULTURE. 



two days of the harvest date. The years 1911 and 1913 were unfa- 

 vorable for wheat. In both these years there was enough water in 

 the fallow plat to start the wheat growing rapidly, but in both years 

 the crop soon commenced to suffer from drought, and the resulting 

 lower rate of water use and low yield are shown. Harvest in both 

 of these years was earlier than in the favorable years. 



A comparison of the two figures shows one striking fact. The 

 wheat on plat A in 1912 used more water than the wheat on plat A 

 in 1909 and made a considerably higher yield. On plat C or D 

 the quantity of water used in 1909 was greater than in 1912, and 

 the yield was higher. For the quantity used, the crop on both plats 

 in 1909 shows a lower yield than in 1912. This is probably explained 

 by the later seeding. 



A comparison of Figures 4 and 5 shows how ineffective in the 

 growth of spring wheat fallowing has been as a means of combating 

 drought at this station. In 1909, 1911, and 1913 there was only a 



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Fig. 5. — Diagram showing the use of water on. wheat plat C or D at Akron, Colo., for 

 the years 1909, 1911, 1912, and 1913. 



little more water in the fallow plat C or D than in the continuously 

 cropped plat A, and only a slightly higher yield was secured. .In 

 1912 the continuously cropped plat A had more water and made a 

 higher yield than the fallow plat C or D. In no year has there been 

 enough additional water stored in fallow above that in continuously 

 cropped land to carry a crop over any prolonged period of drought. 

 In general, the Akron curves represent a condition of water use 

 from a soil of medium water-storage capacity. Comparison of the 

 Akron curves with those of Dickinson shows the difference between 

 the two stations in the quantity of water furnished to a crop through 

 fallowing and the resulting increase in yields on fallow over those 

 on continuously cropped land. 



