220 MOVEMENTS OF SALTS IN THE SOIL 



The next soil, containing 2-358 per cent, of soluble salts in 

 the first 3 inches, failed entirely to yield a growth of barley. 



The last-named soil in the table proved equally sterile ; it 

 contained however a much smaller quantity of alkali salts 

 than the two previously named, but these salts were very 

 rich in sodium carbonate. 



In judging the character of alkali land it is very useful, as 

 pointed out by Hilgard, to ascertain the total quantity of 

 soluble salts in the first 4 ft. of soil ; such a figure represents 

 in fact the whole amount which the agriculturist has at any 

 time to deal with. On the basis of a few such determinations 

 Hilgard concludes that the maximum quantity of alkali salts, 

 consistent with the production of a full crop of barley hay, 

 is from 25,000 Ib. to 32,000 Ib. per acre in 4 ft. of soil, the 

 salts being supposed to contain not more than one-half their 

 weight of sodium carbonate. 



Whitney and Means, in their investigation of the alkali 

 soils in the Yellowstone Valley, take 15,000 Ib. of soluble 

 salts per acre in the surface foot of soil as the limit of possible 

 plant production. The salts in this case were free from alkali 

 carbonates. 



In a report on the salt lands of Habra in Algeria, Berthault 

 and Paturel state (Ann. agronomiques, 1889, xv. 35) that the 

 cultivation of the vine is not hindered by the presence of 0-06 

 per cent, of alkali salts in the soil. When the amount reaches 

 0-08 per cent, in the surface soil, and 0-37 per cent, in the 

 subsoil, the vine languishes, and becomes unprofitable. With 

 0-17 per cent, in the surface soil, and 0-37 in the subsoil, the 

 vine dies. Cereal crops yield a normal harvest with 0-20 per 

 cent, of alkali salts in the soil. All these determinations of 

 saline matter were made in May, when the salts had not fully 



