148 BOARD OF AGRICULTURE. [Pub. Doc. 



cannot be performed by sodium, and hence sodium cannot 

 be made to fully replace potassium in the manures. 



3. It appears that, in the absence of sufficient potassium, 

 sodium in excess of that existing naturally in the soil may 

 be helpful to certain plants, but not to all. 



4. In some instances it seemed possible that sodium might 

 have been helpful by virtue of its indirect action in liberat- 

 ing phosphoric acid and magnesia, but other instances of 

 benefit do not seem to admit of such an explanation. 



5. At the Rothamstead station the beneficial action of 

 sodium salts, which has been frequently observed, is attrib- 

 uted to the advantage of the presence of nitric acid in com- 

 bination with soda rather than with potash, by virtue of the 

 greater solubility of the former salt, on which account the 

 nitrogen was supposed to be more assimilable by plants. 

 The data already at hand at the Rhode Island station do not 

 seem to support this view, for equally as good crops have 

 been secured where no extra sodium was used, thus show- 

 ing the ability of the crops to take up all of the nitrogen 

 they required, even where sodium was not especially applied ; 

 and it seems more probable that where the supply of potas- 

 sium is limited the sodium may, for example, act as a base 

 in the neutralization of acids which are produced within the 

 plant during the synthetical processes, thus perhaps per- 

 forming a part, only, of one of the functions of potassium. 

 This seems more probable than that the sodium was neces- 

 sary in maintaining the turgidity of the plant cells, or in 

 efiecting the translocation of starch, or in promoting other 

 ph3^siological functions. 



(3. There seem to be some plants in connection with whic-li 

 the OTOwth is not beneficiallv influenced bv sodium salts, 

 even in the absence of a sufficient supply of the salts of 

 potassium. 



7. Certain plants, on the other hand, which, like turnips, 

 beets and radishes, arc capable of taking up large amounts 

 of sodium, appear to be directly helped l)y it when the })otiis- 

 sium supply is limited ; while others, such as common millet 

 and oats, which take up only minute (juantities of sodium, 

 exhibit no benefit, under such circumstances, from its use. 



