CEEEAL EXPEEIMEISTTS AT JUDITH BASIN SUBSTATION. 



given for the seven years from 1909 to 1915, inclusive. This table 

 also gives the total and average precipitation and evaporation in this 

 period, with the ratio of the total precipitation to total evaporation. 



Table VI.- — Monthly precipitation and evaporation [in inches) from, a free water surface 

 at the Judith Basin substation, Moccasin, Mont., from April to September of each year 

 from 1909 to 1915, inclusive. 



[Data from the records of the Biophysical Laboratory of the Bureau of Plant Industry.] 





April. 



May. 



June. 



July. 



August. 



September. 



Total. 







Year. 



Pre- 

 cipi- 

 ta- 

 tion. 



Evap- 

 ora- 

 tion. 



Pre- 



cipi- 



ta- 



tion. 



Evap- 

 ora- 

 tion. 



Pre- 

 cipi- 

 ta- 

 tion. 



Evap- 

 ora- 

 tion. 



Pre- 



cipi- 



ta- 



tion. 



Evap- 

 ora- 

 tion. 



Pre- 

 cipi- 

 ta- 

 tion. 



Evap- 

 ora- 

 tion. 



Pre- 



cipi- 



ta- 



tion. 



Evap- 

 ora- 

 tion. 



Pre- 



cipi- 



ta- 



tion. 



Evap- 

 ora- 

 tion. 



Ratio. 



1909 



1910.... ■ 



1911 



1912.... 



1913 



1914.... 

 1915 



1.03 

 1.31 

 1.66 

 1.43 

 .79 

 1.19 

 1.43 



3.00 

 5.18 

 4.10 

 2.62 

 3.89 

 3.21 

 4.70 



1.34 

 2.40 

 2.98 

 3.94 

 2.64 

 2.91 

 2. 12 



4.66 

 5.61 

 5.94 

 4.14 

 4.23 

 4.85 

 4.61 



5.99 

 1.69 

 2.55 

 .64 

 4.77 

 4.64 

 3.97 



6.00 

 , 7.21 

 5.13 

 6.39 

 4.90 

 4.43 

 4.35 



2.54 

 1.10 



.50 

 1.92 

 1.12 



.64 

 3.54 



7.22 

 8.28 

 7.31 

 5.97 

 6.37 

 7.45 

 4.89 



4.21 

 2.02 

 6.34 

 1.27 

 .51 

 .65 

 .92 



7.06 

 7.38 

 6.35 

 6.23 

 7.35 

 7.24 

 6.51 



4.47 

 2.54 

 1.37 

 1.63 

 1.01 

 1.11 

 2.65 



4.67 

 6.48 

 3.41 

 3.42 

 5.83 

 5.10 

 3.43 



19.58 

 11.06 

 15.40 

 10.83 

 10.84 

 11.14 

 14. G3 



32.61 

 40.14 

 32.22 

 28. 77 

 32.58 

 32.27 

 28.49 





1.6 

 3.6 

 2.1 

 2.6 

 3.0 

 2.8 

 1.9 



Average 



1.28 



3.81 



2.92 



4.86 



3.04 



5.49 



1.82 



6.78 



2.27 



6.87 



2.11 



4.62 



13, 35 



32.44 



1:2.4 



The greatest evaporation in any one year, as shown in Table VI, 

 was 40.14 inches (1910). Wliile the seasonal precipitation (Apr. 1 

 to Sept. 30) in 1910 was not quite as low as in some of the other 



Fig. 2. — Map of Montana, showing the average annual precipitation (in inches) at the Judith Basin sub- 

 station and at 24 other poiats in the State. These averages, for the most part, are for 16 years (1898 to 

 1915, inclusive). 



years, the ratio between the precipitation and evaporation was 

 wider than in any other year. The average ratio for the seven years 

 is 1:2.4. A comparison of this ratio with the ratios for the different 

 years gives a very fair basis for judging the seasonal conditions under 

 which the experiments for each year were conducted. 

 48601°— Bull. 398—16 2 



