32 EXPERBIEXT STATION. [Jan. 



unbound nitrogen free. These bacteria act when the air is 

 excluded, deriving their supply of oxygen both from the nitrates 

 and from the protein and carbohydrates of the manure. 



4. Protein-forming bacteria. In order for bacteria to live 

 and multiply they must have as a food a certain amount of 

 nitrogen-containing matter. This they take from the ammonia 

 and nitrates (soluble compounds), and convert it again into the 

 insoluble proteid matter, which naturally does not become again 

 available, and then only gradually, until the bacteria cease to 

 live. Certain molds also act in a similar way. 



Bacteria, therefore, destroy the nitrogenous matter of the 

 manure by converting it into the volatile ammonia compounds 

 and nitrates, and then reconvert a small portion of the ammonia 

 and nitrates back into protein; they also destroy the nitrates 

 and set the elementary nitrogen free. 



If manure is allowed to remain in loose piles exposed to 

 the air for months, about 35 per cent, of its total nitrogen is 

 likely to be lost. The extremes are said to be from 20 to 50 

 per cent. Fully one-third of the total nitrogen lost has been 

 ascertained to be in the elementary form, i.e., uncombined. 

 No method is known for preventing the loss of the uncombined 

 nitrogen. 



Various chemical methods have been tried to catch that por- 

 tion of the nitrogen which escapes in the form of ammonia. 

 The results of the numerous experiments may be summarized 

 as follows : ^ 



Gypsum or Land Plaster. 



As early as 1860 ordinary land plaster or calcium sulfate 

 was recommended, particularly by the German investigator, 

 Grouven, as a substance suitable to catch and hold the volatile 

 ammonia. Later the French investigators, Miintz and Girard, 

 by means of carefully conducted experiments, demonstrated 

 that such material was of no particular value for such a pur- 

 pose. The reports of other investigators confirmed this and 

 showed that the plaster actually hastened the decomposition of 

 the manure. 



' After A. Stutzer, Behandlung und Anwendung der Stalldungera. 



