CROPS ON ALKALI LAND, HUNTLEY PROJECT, MONTANA. 5 



GROUND WATER. 



For the purpose of deteraiinirig the depth of ground water at dif- 

 ferent times of the year, four wells have been made on the experi- 

 ment tract, and measurements were made biweekly during 1913. 

 The results of these measurements are shown in figure 1. The aver- 

 age depth to ground water during 1913 was 3.14 feet. This ranged 

 from 3.76 feet on March 6 to 2.02 feet on October 2, the most rapid 

 rise occurring during the latter part of the irrigation season. 



y.o 



%3* 



TiG. 1. — Diagram showing the depth to ground water on the Worden tract during the year 1913. 



Samples of the ground water were taken from each of these wells 

 during the season of 1913 from June to November, and nine samples 

 from each well have been analyzed. The average results of these 

 analyses are given in Table I. 



Table I. — Results of analyses of ground vjater from the Worden tract in 1913, shoiving 

 the percentages of the substances indicated. 



oAM 



FEB. 



MAP. 



APP. 



MAY 



UUNE 



uuiy 



AUG. 



SEPT 



OCT 



/V<5>K 



DEC. 





































































































/f£AM 















































Well No. 



Total 



salts. 



CaO. 



MgO. 



Na^O. 



C0 3 . 



HCO3. 



CI. 



S0 4 . 



A-l 



A-2 



B-l 



B-2 



1.383 

 2.829 

 1.512 

 1.165 



0. 0549 

 .0737 

 .0178 

 .0193 



0.0719 

 .1289 

 .0521 

 .0268 



0.437 



1.001 



.566 



.431 



None. 



None. 



0.0026 



.0096 



0. 0277 

 .0381 

 .0169 

 .0370 



0. 0136 

 .0294 

 .0109 

 .0098 



0.952 

 1.901 

 1.027 



.788 



Average 



1. 722 



1 



.0414 



.0699 



.609 



.0030 



.0299 



.0159 



1.167 



Table I shows that the water contained an average of 1.722 per 

 cent of total salts and that these consisted chiefly of sulphates. This 

 amount is equal to 1.07 pounds per cubic foot of water. Analysis of 

 the soil showed that it contained an average of 1.77 per cent of total 

 salts. Assuming that a cubic foot of the soil weighs 75 pounds and 

 that it contained an average of 15 pounds of water, this amount would 

 be equal to 1.32 pounds of soluble salts per cubic foot of moist soil, or 

 the concentration of salts in the soil water would be about 9 per cent. 

 This concentration is about five times as great as that of the ground 

 water. 



