COMMERCIAL FERTILIZERS 501 



This table, in addition to confirming the statements 

 already made in regard to the loss of nitrogen in drainage 

 water, also shows how closely the supply of available 

 nitrogen was used by the crops on those plats, which were 

 evidently in need of nitrogen fertilization as the plats 

 lost very little nitrogen during the growing season, while 

 during the remainder of the year they lost nearly as 

 much as did some of the nitrogen-manured plats. The 

 table also indicates that the loss when nitrate is used is 

 greater than when ammonium salts are applied, as the 

 amount of nitrogen in the 550 pounds of nitrate is really 

 eight pounds to the acre more than in the 400 pounds of 

 ammonium sulfate, which is not sufficient to account for 

 the difference in the loss. However, half of the nitrate- 

 treated plat received no other manure and produced only 

 a small crop, which would naturally result in a greater 

 loss by drainage. 



422. Fertilizers containing atmospheric nitrogen. 

 The vast store of atmospheric nitrogen, chemically un- 

 combined but very inert, will furnish an inexhaustible 

 supply of this highly valuable fertilizing element, when it 

 can with reasonable economy be combined in some manner 

 resulting in a product that will be commercially trans- 

 portable and that will, when placed in the soil, be or be- 

 come soluble without liberating substances toxic to plants. 

 The importance of the nitrogen supply for agriculture may 

 be appreciated when it is considered that nitrates are 

 being carried off in the drainage water of all cultivated 

 soils at the rate of twenty-five to fifty pounds, and even 

 more, to the acre annually, and that nearly as much 

 more is removed in crops. 



The exhaustion of the supply of nitrogen in most soils 

 may be accomplished within one or two generations of 



