NURSERY PRACTICE FOR PRAIRIE-PLAINS PLANTING 



45 



Alkalis can be grouped for practical purposes into two classes, viz: 

 White and black alkalis. White alkalis include rather loosely all 

 sulfates and chlorides of sodium, magnesium, and potassium, as well 

 as calcium chloride. These alkalis leave a white crust on the surface 

 of the soil and along irrigation ditches whenever they become concen- 

 trated by surface drying. Black alkali consists of sodium carbonate, 

 leaves dark spots on the surface of the soil, and causes it to become 

 cloddy. The blackish, greasy-looking spots on the surface are caused 

 by action of sodium carbonate in dissolving humus in the soil. 



Alkalis are harmful in several ways. If present in sufficient 

 quantity they reduce or prevent the absorption of water by the plant 

 roots, owing to the high concentration of salts in the soil solution. 



Figure 11. — Failure of Chinese elm due to localized patch of saline soil. 



The result is malnutrition of the plant because of a poor balance of 

 available plant food. Black alkali creates an unfavorable physical 

 condition of the soil known as " puddling." 



The alkalis vary in their toxicity to plants, but all sodium salts are 

 relatively quite toxic. Hilgard (16) states that one-tenth of 1 percent 

 of sodium carbonate, one-fourth of 1 percent of sodium chloride, or 

 one-half of 1 percent of sodium sulfate is the limit of tolerance of some 

 agricultural plants. 



Scofield 03) in discussing alkali problems indicates that, when 

 the total quantity of mixed salts in the soil solution exceeds 1.5 per- 

 cent, plants show injury and it is necessary to leach out the root zone to 

 reduce the amount of alkali. 



Experience in growing deciduous nursery seedlings in the plains 

 indicates that with the exception of some alkali-tolerant species, the 

 trees are less tolerant of alkalis than most agricultural crops. Green 

 ash was found to be seriously stunted in soils where the total soluble 

 salts ran 5,675 pounds per acre or 1,550 parts per million. 11 American 



» Refer? to amount per acre of soil to a depth of 12 

 from 3,430,000 to 3,770,000 pounds in mosl plains nurseries. 



An aere of soil to a depth of 12 inches will weigh 



