74 AMERICAN MANURES. 



in large quantities by the decomposition of com- 

 mon salt. 



Nitrate of Soda, like that of potash, occurs as 

 an incrustation on the surface of the earth, in 

 some places, especially in Chili and Peru, where 

 it is found in beds of considerable thickness. 

 Large quantities of this nitrate are used as ma- 

 nure to furnish nitric acid and soda to the soil. 

 But as most soils contain soda in sufficient quan- 

 tity for the wants of vegetation, the chief value 

 of this product is due to the nitric acid which it 

 contains, and which is a source of nitrogen. 



Soda enters into the composition of plants, 

 but in much less quantity than potash. Some 

 think that if there is a deficiency of potash, soda 

 may wholly take its place ; but this opinion has 

 not, so far as we are informed, been verified in 

 practice. The cheapest mode of furnishing soda 

 to soils is in the form of common salt. 



Common Salt occurs abundantly in nature, 

 both in the earth and in sea water. It is com- 

 posed of chlorine and sodium; 100 parts, when 

 pure, containing 60.68 of chlorine, and 39.32 of 

 sodium. Salt has been applied as manure in all 

 ages and countries ; and yet there is no substance 

 used as manure that has been the subject of so 

 much controversy among practical farmers, some 

 denying that it exerts any beneficial influence, 

 while others ascribe to it wonderful manurial 



