NITRATE OF SODA. 97 



It is only necessary farther to remark, that 

 every crop removed from a soil contains these 

 salts, and unless they are again restored to 

 such soil in the state of manure, or as a pure 

 nitrate, the land must become impoverished 

 and eventually barren. 



In the few cases where the nitrate has failed 

 to produce the effect anticipated, it may pos- 

 sibly be attributed to the absence of the phos- 

 phates of lime and magnesia, and the silicate 

 of potash, all of which are essential to the 

 ffrowth of a white crop, and without which, 

 howsoever abundant the nitrate may be, no 

 crop could be produced. 



It may be, but of this further experience is 

 necessary, that the application of these salts, the 

 nitrates of soda and potash, stimulates peren- 

 nial plants to such an excess, that they are un- 

 able for a time after the action of the salt is 

 over, to compete with similar plants not ex- 

 posed to its action ; but this requires much more 

 observation to confirm the fact, and it does not 

 in any way apply to its use on those crops 

 where it is not only most needed, but at the 

 same time most beneficial. It is only men- 

 tioned here to explain how it is, that in one or 

 two cases where the nitrate of soda was applied 

 during the last spring (1841) to old pastures, 

 and where it produced the most marked and 

 decided effect, that, after the grass was cut and 

 the produce harvested, the after grass was a 

 long time before it came away, and that the 

 grass not manured with this soda then appeared 

 the most luxuriant. This effect however was 



