40 NATURE OF ALKALI INJURY TO THE PLANT 



alkaline and yet there may be a gradual accumulation of 

 salt at the surface of the soil. This condition has the 

 effect of corroding the plant and it often destroys the bark 

 so thoroughly that the passage of elaborated food from 

 leaves to roots is prevented. This injury is rather limited 

 in the total damage done and may be overcome without 

 great expense. 



Formerly it was thought that the principal injury to 

 vegetation by alkali resulted from a corroding action. 

 This is probably not the case, with the possible exception 

 of the carbonates. The carbonates, in addition to any 

 direct action on the plant itself, make the soil hard and a 

 poor medium for the plant. 



REFERENCES 



1. BREAZEALE, J. F. Effect of Sodium Salts in Water Cultures on the 



Absorption of Plant-food by Wheat Seedlings. Jour. Agr. Res. 7 

 (1916), pp. 407-416. 



2. DUGGAR, B. M. Plant Physiology, pp. 64-83. (New York, 1911.) 



3. HARRIS, F. S. Effect of Alkali Salts in Soils on the Germination and 



Growth of Crops. Jour. Agr. Res. 5 (1915), pp. 1-52. 



4. HARTER, L. L. Influence of a Mixture of Soluble Salts, principally 



Sodium Chloride, upon the Leaf Structure and Transpiration of 

 Wheat, Oats, and Barley. U. S. D. A. Bur. PL Ind. Bui. 134 (1908), 

 19 pp. 



5. HICKS, G. H. The Germination of Seeds as Affected by Certain Chemi- 



cal Fertilizers. U. S. D. A. Div. Botany, Bui. 24 (1900), 15 pp. 



6. HILGARD, E. W. Soils, pp. 326-428. (New York, 1906.) 



7. KEARNEY, T. H., and CAMERON, F. K. Some Mutual Relations be- 



tween Alkali, Soils, and Vegetation. U. S. D. A. Rpt. 71 (1902), 

 60 pp. 



8. JOST, L. Plant Physiology, pp. 11-35. (Oxford, 1907.) 



9. KEARNEY, T. H. Plant Life in Saline Soils. Jour. Wash. Acad. of 



Sci. Vol. 8 (1918). 



10. MICHEELS, H. The Mode of Action of Weak Solutions of Electro- 

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