NITROGEN, NITRIFICATION, NITROGENOUS MANURES 135 



NITRIFICATION 

 i 



146. Former Views regarding Nitrification. - - The 



presence of nitrates and nitrites in soils was formerly 

 accounted for by oxidation. The theory was held that 

 the production of nascent nitrogen by the decomposition 

 of organic matter caused a union between the oxygen 

 of the air and the nitrogen of the organic matter. Fer- 

 mentation studies by Pasteur led him to suggest in 1862 

 that possibly the formation of nitric acid in the soil 

 might be due to fermentation. It was, however, fifteen 

 years later before the French chemists, Schlosing and 

 Muntz, established the fact that nitrification is pro- 

 duced by a living organism. They passed diluted sew- 

 age through a glass tube filled with sand to which a 

 little lime was added. The first portions of sewage 

 contained nitrogen in the form of ammonia, but after a 

 number of days nitrates appeared, and the ammonia 

 diminished. When the soil was treated % with chloro- 

 form vapor, nitrates ceased to be formed ; when fresh 

 garden soil was added, nitrates again appeared in the 

 leachings. The bacteria were destroyed by the chloro- 

 form, and the medium was reseeded from the garden 

 soil. 



147. Nitrification caused by Micro-organisms. --Nitri- 

 fication is the process by which nitrates and nitrites are 

 produced in soils by the workings of organisms. Nitri- 

 fication results in changing the complex organic nitro- 



