498 



PRINCIPLES OP SOIL MICROBIOLOGY 



Nitrogen transformation in the rotting of manure. About half of the 

 nitrogen in manure is in the form of ammonia (and urea) and half is 

 in the form of proteins and other complex nitrogen compounds. The 

 first part of the nitrogen rapidly changes into nitrates before the micro- 

 organisms, using the constituents of the straw and other undecom- 

 posed materials, have a chance to absorb it and change it into organic 

 complexes. The second part has to be gradually decomposed before 

 the nitrogen can be made available; for this a considerable period of 

 time is required. 72 The final product in the decomposition of the 

 proteins, of the urea and of the other nitrogen compounds of the manure 

 is chiefly ammonia. A small part of it may be lost to the atmosphere 



TABLE 44 



Transformation of nitrogen in the composting of manure under aerobic and 



anaerobic conditions 7 ^ 



NHrN 



NO3-N 



NO2-N 



AMIDE-N 



OTHER N 

 COM- 

 POUNDS 



(proteins) 



Anaerobic conditions 



Start 



6°C for 50 days, 

 26°C for 50 days 



Start 



15°C 



26°C 



per cent 



100 

 95 

 98 



Aerobic conditions 



100 

 72 

 69 



through volatilization 73 but a much greater part is retained in the 

 manure, as such, by physical or chemical agencies. A part of the 

 ammonia is nitrified and a part is reabsorbed by the bacteria and fungi 

 in the manure in the process of their metabolism for which the straw 

 of the manure is used as a source of energy. Another source of loss, 

 in the decomposition of manure, is the evolution of gaseous nitrogen, 

 either through denitrification or through the chemical interaction of 



72 Barthel, Chr. Neuere Untersuchungen iiber die Ausniitzung des Stall- 

 miststickstoffs im Ackerboden. Fortschr. der Landwirtsch., 1: H. 2. 1926. 



73 Ehrenberg, P. Die Bewegung des Ammoniakstickstoffs in der Natur. P. 

 Parey. Berlin. 1907. 



