CEREALS ON THE BELLE FOURCHE EXPERIMENT FARM. 7 
In figure 3 are shown graphicayy the " useful " seasonal precipita- 
tion and the yields of Kubanka durum spring wheat (C. I. No. 1516) 
during the 12 years from 1908 to 1919, inclusive. The " useful " 
precipitation shown is the total precipitation in rains of 0.3 inch 
or more during the period between the emergence and ripening of the 
Kubanka wheat each year. When the rains occurred during a period 
of two, three, or four consecutive days the total amounts for the 
72 
08 '03 70 7/ 72 73 74- 75 76 77 78 79 
l~~~U<S£FUL lsS/?io/V^L P/?EC/P/T/9T/OA/ 
Y/ELD PET? &C&E (&V&rt£Ldi) 
BU 
60 
Fig. 3. — Diagram showing the relation between the annual useful seasonal precipitation 
and the yields per acre of Kubanka durum spring wheat on dry land at the Belle Fourche 
Experiment Farm for the 12-year period from 1908 to 1919, inclusive. The broken line 
shows the useful precipitation and the solid line the yields of Kubanka wheat. 
period were included even though less than 0.3 inch fell on some 
of these days. The Kubanka variety of wheat was selected be- 
cause it was the leading variety, was grown each year, and w T as not 
seriously affected by rust. 
In figure 3 it will be seen that the yields of Kubanka wheat are 
closely associated with the useful seasonal precipitation during most 
of the years. In 1909 and 1914 the wheat was on poorer soil than 
usual. In 1912 most of the rains came just before the wheat was ripe 
and too late to be of benefit. The crop was a complete failure in 
