THE SUBSTITUTION OF SODA FOE POTASH IN 



PLANT GROWTH.* 



W. H. Jordan and C. G. Jenter. 



SUMMARY. 



Experiments relating to the possibility of substituting soda 

 for p'otasli in plant growth have been carried on during two 

 years, with the following results: 



(1) A deficiency of available potash greatly depressed the 

 growth of the plant even in the presence of an abundant supply 

 of soda salts. A lack of soda in the presence of potash sufQcient 

 for the plant's needs seemed to have no deleterious effect what- 

 ever npon growth. 



(2) Plants to which the necessary supply of potash was not 

 accessible took up more soda than when potash was present in 

 abundance. Soda may be substituted for potash in quantity 

 when the latter is lacking. 



(3) While the substitution may take place in quantity, it evi- 

 dently cannot do so in function, as is shown by the limited 

 growth when the plants were deprived of potash, even though 

 soda was appropriated in increased proportions. 



(4) The experiments incidentally suggest the view that the 

 real need of plants for certain essential mineral constituents is 

 not even approximately measured by the proportions of these 

 constituents which the plant takes up. 



♦Reprint of Bulletin No. 192. 



