133 MANURES . 



where it has given great value to land that was pre- 

 viously not fit for cultivation. Quite recently, com- 

 panies have been formed for its shipment to other 

 places near the coast, and it promises to become 

 of great importance wherever it can be cheaply 

 procured. 



An analysis of this manure is given in Section V 



SODA. 



Soda, the requirement of which is occasioned by 

 the same causes as create a deficiency of potash, 

 and all of the other ingredients of vegetable ashes, 

 may be very readily supplied by the use of common 

 salt (chloride of sodium), which is about one-half 

 sodium (the base of soda). The best way to use 

 salt is in the lime and salt mixture, previously 

 described, or as a direct application to the soil. If 

 too much salt be given to the soil it will kill any 

 plant. In small quantities, however, it is highly bene- 

 ficial, and if six bus/iels per acre be sown broadcast 

 over the land, to be carried in by rains and dews, it 

 will not only destroy many insects (grubs and worms), 

 but will prove an excellent manure. Salt acts direct- 

 ly in the nutrition of plants, as a source of necessary 

 chlorine and soda. There is little doubt, however, 

 that its chief value as a manure in most instances arises 

 from the fact that it renders other plant foods more 

 soluble, and assists in preparing them for use. Salt, 

 even in quantities large enough to denude the soil of 

 all vegetation, is never permanently injurious. After 



