CHAPTER V 

 TOXIC LIMITS OF ALKALI 



Numerous attempts have been made to determine the 

 approximate quantity of the different alkali salts, both 

 singly and in various combinations, which may be with- 

 stood successfully by crops. Some experimenters have 

 confined their- work almost entirely to field observations. 

 Others have worked with natural alkali soils from the 

 fields or soils made alkaline by the addition of salts in 

 definite quantities and sown to crops under laboratory 

 conditions. Still others have used different solutions 

 containing salts as the medium for determining the toxicity 

 of salts to plants. Each method has both advantages and 

 disadvantages. 



The field work has often been done by sampling soils 

 showing injury to plants and also adjoining soils where 

 the effects of the alkali could not be detected. These 

 observations are usually taken after the crop has made 

 considerable growth, when the extent of injury may be 

 estimated by the appearance of the plants. Such deter- 

 minations may not take into consideration conditions pre- 

 vailing during the earlier stages of growth. The vigor and 

 delicacy of the plant at the time the alkali comes in contact 

 with it appear to have much to do with its tolerance. 

 Alfalfa, sugar-beets, and a number of other plants do not 

 withstand alkali well in their seedling stages, but are 

 among the most tolerant during later stages of growth. 

 Most plants do better under alkali conditions as maturity 



