PART III. -THE MANUFACTURE OF 

 FERTILIZERS 



SECTION I.-INORGANIC NITROGEN 

 FERTILIZERS 



THE nitrogen fertilizers differ from one another in chemical 

 and physical properties to a remarkable extent. Such 

 fertilizers as ammonium sulphate, sodium nitrate, calcium 

 cyanamide and protein exhibit no physical resemblance to 

 one another, and no chemical resemblance, excepting that 

 they all contain between 15 % and 20 % of nitrogen. That 

 such a varied assortment of materials should exhibit similar 

 effects on plant growth is due to the fact that they all decom- 

 pose in the soil with the production of calcium nitrate. 

 Ammonium sulphate, (NH 4 ) 2 SO 4 , contains nitrogen in the 

 form of an alkaline substance ammonia ; sodium nitrate, 

 NaNO 3 , contains its nitrogen 'in the fully oxidized form of 

 nitric acid : both these materials are nearly pure chemical 

 compounds very stable and easily soluble in water. Calcium 

 cyanamide, CaCN 2 , is a very peculiar organic compound. In 

 the crude form of the fertilizer as manufactured, only 50 % 

 of pure calcium cyanamide occurs. Calcium cyanamide is 

 not very stable, and dissolves very easily in water. Protein 

 contains its nitrogen in the form of complex amino acids. 

 As a rule, the protein is insoluble in water when it may be 

 regarded as a colloidal " gel." When the protein is soluble 

 it forms a colloidal solution. Protein forms an excellent 

 food for most forms of soil organisms, and is broken down by 

 them into simpler nitrogen compounds. 



Sulphate of Ammonia. The ammonia liquor obtained 

 from gas works, coke ovens, blast furnaces, etc., as described 

 on p. 48, is used for the manufacture of ammonium 

 sulphate b}^ a process of distillation. Other methods which 



