96 NITRATE OF SODA. 



that plants after a certain stage, derive their 

 principal nutriment from the atmosphere, and 

 not from the soil; and the increased action 

 that is given to plants from the supply of ni- 

 trogen and soda, enables them to assimilate 

 more carbon from this source. 



A farther proof that the application of -ni- 

 trate of soda has a contrary effect, is known 

 from the circumstance, that crops growing on 

 land that had been dressed during the pre- 

 ceding year with this manure, have during 

 the second season showed the beneficial result 

 of the application, in increased luxuriance, 

 and by their rank deep colour ; a circumstance 

 entirely to be attributed to a portion of the 

 manure still remaining in the soil. Another 

 circumstance corroborative of the truth of these 

 opinions may be collected by reflecting on the 

 routine that is too frequently observable on 

 farms, where a judicious system of agriculture 

 is overlooked ; for instance, many crops are an- 

 nually removed from a certain pasture, and no 

 manure applied until the land becomes entirely 

 exhausted, and w^hen in this state, the applica- 

 tion of the nitrate of soda or potash, at once 

 restores abundance and a rank vegetation. In 

 such instances as these, it cannot force the soil, 

 because on all hands it must be admitted that the 

 land was entirely exhausted; any increase, there- 

 fore, must be entirely attributable to the efforts 

 produced by the presence of these salts. The 

 same remarks will apply to other manures, 

 such as chalk, lime, &c. and will be mentioned 

 under their respective h^ads. 



