THE SUBSTITUTION OF SODA FOR POTASH IN 
PLANT GROWTH* 
WW. H. Jorpan anno C. G. JENTER. 
SUMMARY. 
Experiments relating to the possibility of substituting soda 
for potash 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 sufficient 
for the plant’s needs seemed to have no deleterious effect what- 
ever upon 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. 
