BULLETIN 546, U. S. DEPARTMENT OF AGRICULTURE. 



METHODS USED IN THE EXPERIMENTS. 



The experiments were conducted in field P, Series I, II, III, 

 and IV, seven tenth-acre plats being used in each series. A 

 diagram of these plats is shown in figure 1. The land was first 

 broken in August, 1911, and it produced oats in 1912 and again 

 in 1913. It is uniform in topography and soil. The crops of 1912 

 and 1913 were harvested from the field as a whole, no record having 

 been secured of the production of the different series of plats. Series 

 II and IV were irrigated on November 11, 1913, November 11, 1914, 

 and November 10, 1915. Except for this fall irrigation, the treat- 











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Pig. 1.— Diagram of a part of field P, Belle Fourche Experiment Farm, showing the location of the plats 

 used in the fall-irrigation experiments. The arrows indicate the direction of the flow of the water in 

 the irrigation laterals supplying these plats. 



ments applied to Series II and IV were uniform with those applied 

 to Series I and III. 



The fall irrigation was applied each year after the plats were 

 plowed, except that in the autumn of 1914 the plats which that year 

 had produced intertilled crops were not plowed. Low earth dikes 

 were thrown up at the lower side of the plats to impound the water 

 sufficiently to insure a complete covering of the land. The water 

 was then applied by flooding and allowed to run on each plat from 

 three to four hours. The summer irrigation of each crop was uni- 

 form on all four series as to both time and method of application. 

 No attempt was made to measure the water applied, but the meth- 

 ods of irrigation recognized in the locality as good-farming methods 

 were followed. The sugar beets and potatoes were irrigated by the 

 furrow method and the other crops by field flooding. 



