250 THE SMALL GRAINS 



mentioned (246) . So long as these substances do not occur 

 in extreme amounts, they are very beneficial in furnishing 

 plant-food, and in their good effects on the physical condi- 

 tion of the soil. In the drier portions of prairie regions 

 near the mountains, these substances occur in excess, 

 producing alkali lands. As the cereals are adapted to 

 prairie lands, one would also expect them to be rather 

 tolerant of alkali. This is true to a considerable degree. 



267. Alkali tolerance in cereals. While all the small 

 cereals are somewhat alkali-resistant, they differ con- 

 siderably from each other in that respect. Barley is the 

 most resistant, according to field experiments of Lough- 

 ridge (1901, pp. 26-27). Barley was grown to a height of 

 4 feet in land containing 12,000 pounds of carbonate of 

 sodium to the acre, in 4 feet depth, and produced more 

 than one ton of hay in presence of over 5000 pounds of 

 common salt to the acre. It is better adapted for alkali 

 land than wheat. 



The limit of tolerance in wheat reached 1480 pounds of 

 sodium carbonate to the acre. Common salt began affect- 

 ing wheat injuriously at a concentration of 3920 pounds 

 to the acre-4 feet. So-called gluten wheat made excel- 

 lent growth in the presence of 24,300 pounds of alkali to 

 the acre, of which nearly 1500 pounds was common salt. 

 From all results so far, the conclusion was drawn that 

 wheat should do well in deep loose soils, having not more 

 than 20,000 pounds total alkali to the acre-4 feet, if 

 there is not over 1200 pounds of common salt or sodium 

 carbonate. Rye, although grown at the same time, was 

 not fairly tested as to alkali tolerance. 



268. Pot experiments on cereal tolerance of alkalies. 

 Leather found in pot experiments that maize was least 

 affected of all cereals by alkalies. Analyses of soil sam- 



