ANAEROBIC BACTERIA 179 



from proteins is very active under anaerobic conditions. 82-84 Two 

 maxima were found for nitrogen-fixation in the soil, one under aerobic 

 and another under anaerobic conditions; 83 - 86 a higher fixation may 

 actually be obtained anaerobically. 87 The decomposition of cellulose 

 under anaerobic conditions is carried on entirely by bacteria. The 

 phenomena of reduction under anaerobic conditions, especially that of 

 nitrates, may become an important economic factor. 



It is important to point out, in this connection, the active role 

 which anaerobic bacteria play in the rotting of manure. As a matter of 

 fact, the lowest loss of nitrogen and the most efficient conservation of the 

 important elements of the manure is accomplished by keeping it com- 

 pact and moist, so as to prevent the action of aerobic fungi and bacteria 

 and stimulate the action of anaerobic bacteria. As far back as 1889, 

 Schloesing 88 pointed out that under anaerobic conditions there is no 

 loss of nitrogen. The gases were found to consist of equal volumes of 

 methane and carbon dioxide, when the manure is incubated at 52°C. 

 Water takes part in the reaction supplying some oxygen for the forma- 

 tion of C0 2 and some hydrogen for the methane. The amount of gas 

 produced per hour rapidly increases until it reaches a maximum on the 

 6th day, when it begins to diminish. At 42°C, 850 cc. of gas collected 

 from the decomposition of 100 gm. of manure consisted of 713.6 cc. 

 C0 2 , 97.6 cc. methane and 38.8 cc. hydrogen. 



Further information on the decomposition of proteins and carbo- 

 hydrates under anaerobic conditions and on the nature of soil gases is 

 given elsewhere (p. 638). 



» 2 L6hnis, 1905 (p. 120). 



83 Traaen, A. E. Uber den Einfluss der Feuchtigkeit auf die Stickstoff um- 

 setzungen im Erdboden. Centrbl. Bakt. II, 45: 115. 1916. 



84 Murray, T. J. The oxygen requirements of biological soil processes. Jour. 

 Bact. 1: 597-614. 1916. 



85 Greaves, J. E. Azofication. Soil Sci. 6:163-218. 1918. 



86 Lipman and Sharp, 1915 (p. 584). 



87 Panganiban, E. H. Rate of decomposition of organic nitrogen in rice paddy 

 soils. Phillip. Agriculturist, 12: 63. 1923; Temperature as a factor in nitrogen 

 changes in the soil. Jour. Amer. Soc. Agron. 17: 1-31. 1925. 



88 Schloesing, 1889 (p. 62). 



