6 BULLETIN 297, U. ,S. DEPARTMENT OF AGRICULTURE. 



Fort Meade is only about 25 miles south of Newell, but the eleva- 

 tion is 675 feet greater. Its proximity to the Black Hills apparently 

 influences the rainfall to a considerable extent, as the annual precipita- 

 tion is greater at Fort Meade than at Newell in those years for which 

 the rainfall records of both are available. A comparison of Tables II 

 and III, however, will indicate to some extent the frequency with 

 which conditions of precipitation similar to those prevailing from 1908 

 to 1913 are to be expected. 



The mean annual rainfall at Fort Meade, as shown by Table III, is 

 19.86 inches for the 33 years from 1881 to 1913. The maximum rain- 

 fall for the period, 30.37 inches, was recorded in 1905. The minimum 

 rainfall, 8.40 inches, was recorded in 1911. For practically all of this 

 year, however, there are no records at Fort Meade, so that the rainfall 

 at Vale, S. Dak., has been substituted. The rainfall at Vale is usually 

 considerably lower than at Fort Meade, though the two points are 

 only about 16 miles apart. The lowest annual rainfall actually re- 

 corded at Fort Meade is 13.25 inches, the record for 18S5. 



The rainfall during the growing period for cereals (March to July) 

 also shows a wide variation. The average seasonal rainfall for the 

 33-year period is 13.45 inches. The maximum rainfall for the five 

 months, 26.43 inches, was recorded in 1907; the minimum (except 

 that of 1911 at Vale), 7.36 inches, was recorded in 1885. In the six 

 years covered by the experiments at Newell the rainfall at Fort 

 Meade during the growing season has exceeded the normal only in 

 1909. 



EVAPORATION. 



The seasonal evaporation probably ranks next in importance to 

 seasonal precipitation among the factors which influence the growth 

 of crops at Newell. The daily evaporation has been recorded at the 

 Belle Fourche Experiment Farm, and the total amount in inches by 

 months from April to July is shown in Table IV. The record of 

 evaporation was not kept for the month of March, but at Newell crops 

 ordinarily make little growth during that month and hence this omis- 

 sion is not of importance. The evaporation is determined from a 

 free water surface, the method being that employed at all of the 

 stations where the Biophysical Laboratory of the Bureau of Plant 

 Industry has been cooperating. 1 



The average evaporation for the four months from April to July, 

 inclusive, for the six years from 1908 to 1913 was 27.620 inches. The 

 lowest total evaporation, 23.627 inches, was recorded in L909, the 

 year of the greatest rainfall during the same months. The highest 

 total evaporation, 33.906 inches, was recorded in 1011, the year of 

 the lowest seasonal rainfall. Thus, the evaporation usually varies 

 inversely with the precipitation, though this is not always the case. 



1 Briggs, L. J., and Belz, J. O. Dry farming in relation in rainfall and evaporation, CJ. S. Dept. \ ■> .. 

 Bur. Plant Indus. Bill. 188, p. 16-20. 1910. 



