BULLETIN 291, U. S. DEPARTMENT OF AGRICULTURE. 



PRECIPITATION. 



The climate of western South Dakota is fairly typical of that of 

 the semiarid Great Plains, which extend from western Texas into 

 the prairie provinces of western Canada. The precipitation decreases 

 steadily from the eastern border of the State to the western, being 



least in the north- 

 /34//U/54/.Z /a/ /a/cms? west corner. 



? S ? -^ * The Black Hills 



modify the climate 



of the immediately 

 surrounding country 

 to a great extent, 

 mainly by increasing 

 the precipitation. 

 This effect extends 

 several miles beyond 

 the outlymgfoothills. 

 The Belle Four die 

 farm is situated about 30 miles from the foothills and, so far as known, 

 is not influenced to any extent by proximity to the Black Hills. The 

 annual and average precipitation by months at the Belle Fourche Ex- 

 periment Farm for the six years from 1908 to 1913 is given in Table 

 II. Except as noted, these data were recorded at the station. The 

 annual and seasonal rainfall is shown graphically in figure 1 . 



Table II .— Monthly , seasonal, and annual precipitation at the Belle Fourche Experiment 

 Farm for the six years from 1908 to 1913, inclusive. 



[Data (in inches) from the records of the Biophysical Laboratory of the Bureau of Plant Industry, except 



as noted.] 



Fig. 1.— Diagram showing the annual and seasonal precipitation at 

 the Belle Fourche Experiment Farm, for six years, 1908 to 1913, in- 

 clusive. Solid bars show the seasonal precipitation, while the total 

 length of the bars shows the annual precipitation. 



Year. 



Jan. 



Feb. 



Mar. 



Apr. 



May. 



June. 



July. 



Aug. 



Sept. 



Oct. 



Nov. 



Dec. 



Sea- 

 sonal. 



To- 

 tal. 



1908 



a0.20 

 a. 17 

 .73 

 .13 

 .24 

 .57 



o0.19 

 a. 23 

 .70 

 .05 

 .10 

 .24 



al.65 

 a. 19 

 .93 

 .09 

 .71 

 .99 



1.16 

 .84 



1.57 

 .17 



2.32 

 .25 



3.95 

 3.87 

 1.26 

 .45 

 2.26 

 1.98 



1.47 

 5.59 

 1.51 

 .50 

 .29 

 3.10 



1.26 

 2.45 

 1.42 



.so 



3.20 

 .35 



0.62 

 .55 

 1.03 

 L.86 

 2.80 

 .26 



0.52 

 1.07 

 2.92 

 .92 

 3.49 

 2.38 



a2. 10 



.76 

 .27 

 .39 

 .51 

 1.86 



a0.20 

 .73 

 .11 

 .98 

 .04 

 .10 



"0.91 

 1.28 

 .10 

 .30 

 .13 

 .45 



9.49 

 12. U4 

 6. 69 

 2.01 

 8.78 

 6.67 



14.23 



1909 



17.73 



1910 



12.55 



1911 



6.64 



1912 



16. 09 



1913 



12.53 



Average... 

 Maximum 

 Minimum. 



.37 

 .73 



.13 



.26 



.70 

 .05 



.76 

 1.65 

 .09 



1.05 

 2.32 



.17 



2.29 



3.95 



.45 



L'.IIS 



5.59 



.29 



1.58 



3.20 



.35 



1.19 



2.80 



. 26 



1.88 



3.49 



.52 



.97 



2.10 



.27 



.36 

 .98 

 .04 



.53 



1.28 



.10 



7.76 

 12.94 



2. 01 



111. 41 

 17.73 

 6.64 



a From records of the United States Weather Bureau al Vale and at < >rman, S. Dak. 



The average precipitation at the Belle Fourche Experiment Farm 

 during the 6-year period under discussion (190S-1913), as shown in 

 Table II, was 13.41 inches. Of this total, 7.76 inches fell during the 

 months from March to July, inclusive, or during the period when 

 small grains make most of their growth. The annual precipitation 

 varied from 6.64 mches in 1911 to 17.73 inches in 1909. The seasonal 



