CROPS ON ALKALI LAND, HUNTLEY PROJECT, MONTANA. 



11 



year. This practice was continued during the season of 1912 from 

 May until September, the land being cultivated and irrigated at 

 about 10-day intervals. The cultivating was done with a beet 

 cultivator equipped with bull-tongue shovels, and the ground was 

 leveled with a float before each irrigation. 



Effect on the salt content. — Determinations, by means of the elec- 

 trolytic bridge, were made of the total salts in the soil on these plats 

 during the seasons of 1911, 1912, and 1913. Samples were taken at 

 irregular intervals in 1911 and 1912. In 1913 complete sets of 

 samples were taken in May, June, July, September, and October. 

 In 1911 and 1912 samples of the following layers of soil were taken: 

 Top 3 inches, 3 to 6 inches, 6 to 12 inches, 12 to 24 inches, and 24 

 to 36 inches. In 1913 samples were taken of the same layers and 

 also of the 36 to 48 inch layer. It was found, however, that the salt 

 content at 48 inches did not differ materially from that at 36 inches, 

 so that only the surface 36 inches of soil are considered in the com- 

 parisons here given. Table VI shows the average salt content at 

 specified depths in 1911, 1912, and 1913 expressed as percentages 

 of air-dry soil. 



Table VI. — Average total salt content of soil to a depth of 3 feet on plats which had 

 received treatment according to the second method in 1911, 1912, and 1913. 



Year. 



Number 

 of borings. 



Top 3 



inches. 



3 to 6 



inches. 



6 to 12 

 inches. 



Average, 

 .first foot. 



12 to 24 Average, 

 inches, top 2 feet. 



24 to 36 

 inches. 



Average, 

 top 3 feet. 



1911 



1912 



1913 



32 

 36 

 40 



0.31 

 .26 

 .25 



0.36 

 .33 



.34 



0.54 

 .51 

 .60 



0.43 

 .40 

 .44 



1.30 



.89 



1.01 



0.86 

 .64 

 .72 



2.07 

 1.68 

 1.75 



1.26 



.99 



1.07 



A study of Table VI shows that there was a reduction of 0.27 per 

 cent in the average salt content of the upper 3 feet of soil from 1911 

 to 1912 and that there was an increase in 1913 over 1912 of 0.08 per 

 cent. This increase occurred mainly in the second and third feet 

 and accompanied the rise of the ground-water table during 1913. 



In Table VII the average salt content to a depth of 4 feet in 1913 

 on these plats is compared with the average salt content of adjacent 

 virgin soil in the same year. The samples were taken in May, June, 

 July, September, and October, and the results are expressed in per- 

 centages of air-dry soil 



Table VII. — Average total salt content of soil to a depth of 4 feet on plats which had 

 received treatment according to the second method and of adjacent virgin soil in 1913. 



Treatment. 



Num- 

 ber of 

 borings. 



Top 3 

 inches. 



3 to 6 

 inches. 



6 to 12 

 inches. 



Aver- 

 age, first 

 foot. 



12 to 24 

 inches. 



Aver- 

 age, top 

 2 feet. 



24 to 36 

 inches. 



36 to 48 

 inches. 



Aver- 

 age, top 

 4 feet. 



Second method. 

 Virgin soil 



Difference. 



0.25 

 .65 



0.34 

 .92 



.58 



0.60 

 1.54 



0.44 

 1.16 



1.01 

 1.83 



0.72 

 1.49 



1.75 



2.08 



.94 



1.45 

 1.79 



.34 



1.16 

 1.71 



