CHAPTER XVII 

 COMMERCIAL SOURCES OF PLANT-FOOD 



Acquaintance with Terms. The hesitation 

 of many users of commercial fertilizer to master 

 the few technical terms used in analyses of the 

 goods, for which over one hundred million dollars 

 annually are expended in this country, is to be 

 deplored. The number of the materials avail- 

 able for any large use as sources of plant-food in 

 a commercial fertilizer is small, and something 

 of their characteristics should be known. Every 

 farmer should have a working knowledge of these 

 materials their sources, the percentage of plant- 

 food carried by them, and their probable avail- 

 ability. He should know in a general way their 

 advantages and disadvantages in comparison 

 with each other. 



Nitrate of Soda. One of the best carriers of 

 nitrogen is nitrate of soda, which is imported from 

 Chili, South America, where great beds exist. 

 The most of the impurities are removed, and the 

 nitrate of soda comes to us in bags holding 200 



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