328 THE PRINCIPLES OF SOIL MANAGEMENT 



evidently in need of nitrogen fertilization, as these 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. 

 It 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 per acre more than in the 400 pounds 

 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 a greater loss by drainage. 



195. Calcium cyanamid. The vast store of atmos- 

 pheric nitrogen chemically uncombined, but very inert, 

 will furnish an inexhaustible supply of this highly valu- 

 able fertilizing element, when it can be, with reasonable 

 economy, combined in some manner that will result 

 in a product commercially transportable, and that will, 

 when placed in the soil, be or become soluble without 

 liberating substances toxic to plants. The importance 

 of the nitrogen supply for agriculture may be appreciated 

 when we consider that nitrates are being carried off 

 in the drainage water of all cultivated soils at the rate 

 of from twenty-five to fifty pounds and even more per 

 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 men, unless a renewal of the supply be brought about 

 in some way. Natural processes provide for an annual 



