NITRATE OF SODA. 95 



with the peculiar acid each plant contains, and 

 the carbon thus set free, performs the functions 

 attributed to it in a preceding chapter. 



But if the soda is applied in the state of a 

 nitrate, as is now generally the case, especially 

 as a top dressing for white crop, its action is 

 somewhat different. 



In this state the salt, after having been dis- 

 solved and absorbed by the roots, is decom- 

 posed, but in this latter case, nitrogen is assi- 

 milated to form the gluten in the seed, and to 

 enter into the other parts of the plant. 



It is a popular opinion that these salts act on 

 the various soils as stimulants, and that al- 

 though they may increase the vegetation for a 

 season, still that their use is injurious, as they 

 exhaust the soil in the same degree in which 

 the crops are improved. A greater fallacy 

 than this it is scarcely possible to conceive, and 

 even had we not the experience of facts to fall 

 back on, it could be satisfactorily proved that 

 the action of soda and potash, and especially 

 of the nitrates of these salts, are of themselves 

 the cause of the increased luxuriance, and that 

 the soil is, and must be benefited by their ap- 

 plication. Thus, when the nitrate of soda is 

 applied as a top dressing, it is absorbed and 

 decomposed, as already seen ; and, of itself is 

 the cause of the increased weight of the crop 

 and the luxuriant vegetation. It may possibly, 

 and does by giving increased vigour to every 

 part. of the plant, enable it thereby to absorb 

 more nutriment from the air, but it has been 

 already, and it is hoped, sufficiently explained, 



