TILLAGE AND ROTATION EXPERIMENTS AT NEPHI, UTAH. 3 



normal in 1908 and 1909, with 16.66 and 16.19 inches, respectively; 

 while in 1910, 1911, 1912, and 1913 it was below normal, with 9.08, 

 10.11, 12.61, and 12.34 inches, respectively. The average annual 

 precipitation for these last four years was only 11.03 inches. 



Most of the annual precipitation of the past 16 years has fallen 

 during the months of March, April, and May, the latter month having 

 the highest average. The months of June and July have been by 

 far the driest months. A large part of the precipitation from Novem- 

 ber to March, inclusive, has fallen in the form of snow. 



Most of, the rainstorms at Nephi have been small and generally 

 almost negligible. This is especially true of the storms which have 

 occurred from March to August, inclusive. Such showers are of 

 little value to the crops, because they fall upon a hot, dry surface 

 and the moisture is soon lost by evaporation. It has been observed 

 that showers of less than 0.5 inch are of little value when considered 

 singly. When wet days follow each other consecutively, however, 

 thus reducing the evaporation and leaving the surface soil wet, a fall 

 of even 0.5 inch of rain is of value. 



EVAPORATION. 1 



The average evaporation at Nephi during the six months from 

 April to September, inclusive, has been about 45 inches. The lowest 

 total evaporation, 40.53 inches, was recorded in 1909; the highest, 

 50.26 inches, was recorded in 1910. The lowest average daily evapo- 

 ration has been recorded in April and the highest in July; however, 

 there was little difference in the evaporation of June, July, and 

 August. 



WIND. 



Strong winds or protracted hot winds are practically unknown in 

 the vicinity of the Nephi substation, while many summer days pass 

 without any appreciable movement in the atmosphere. When wind 

 does blow, it is usually from the south or southwest in the morning, 

 changing gradually during the day until by evening it is blowing from 

 the north or northwest. The average velocity for any one day sel- 

 dom reaches 10 miles an hour. 



TEMPERATURE. 



The highest mean and maximum monthly temperatures during the 

 growing season have been recorded in July, while the lowest have 

 been recorded in April and October. No records have been kept 

 from November to March, inclusive. Comparatively low tempera- 

 tures are reached in winter, sometimes as low as —20° F., but serious 

 injury to the fall-sown crops does not result if the ground is covered 



1 Instruments for measuring evaporation, wind velocity, and temperature, and the apparatus used in 

 making soil-moisture determinations were furnished by the Biophj'sical Laboratory of the Bureau of Plant 

 Industry, which is cooperating in the work at Nephi. 



