Nitrogenous Fertilizers 49 



quantity now made is increasing annually, largely be- 

 cause of the improved methods used in the manufacture 

 of coke, which permit the saving of the ammonia. 

 Its chief advantages are that it is very concentrated, 

 therefore reducing the cost of handling; it is always in 

 the same form, a distinct and definite product, thus render- 

 ing its purchase a safe proceeding; and it is very quick 

 to act, thus making it a very useful form, especially for 

 quick-growing crops. Its physical character is such as to 

 permit its ready distribution in a mixture. On the other 

 hand, it should not be mixed with an alkaline material, 

 in which case the ammonia is liberated. Such substances 

 are wood-ashes, basic-slag, potassium carbonate and slaked 

 or burned lime. 



Calcium cyanamid is not an ammonia compound, but 

 it is thought wise to consider it here because it is believed 

 that it undergoes a gradual change when brought in 

 contact with soil moisture and forms ammonia. It is a 

 comparatively new product made possible by the develop- 

 ments in the world of electricity. This material, some- 

 tunes called lime-nitrogen, is now being manufactured, 

 by two plants in this country. In its manufacture 

 finely divided calcium carbide is placed in a heated 

 retort, into which nitrogen, obtained by liquefaction of 

 air and distillation, is passed. The resultant material 

 is removed in the form of a hard cake which is finely 

 ground, and after thorough aeration is ready for distribu- 

 tion. When calcium cyanamid is free of impurities 

 it contains 35 per cent of nitrogen, but the commercial 

 product seldom exceeds 15 per cent. While its avail- 

 ability ranks with other ammonium salts it has the 

 disadvantage of causing injury to young plants unless 

 it is distributed in the soil some time before planting. 



