448 PRINCIPLES OF SOIL MICROBIOLOGY 



Under aerobic conditions, Koch 63 obtained a more favorable nitrogen 

 fixation by Azotobacter. 



Koch found stronger cellulose-decomposing bacteria in manure than 

 in normal soil and, therefore, suggested that the beneficial effect of 

 stable manure is due to the introduction of strong cellulose decomposing 

 bacteria, as shown by the increased action of green manure when it is 

 inoculated with a small amount of stable manure. The more rapid 

 decomposition of the green manure results in an increased nitrogen 

 fixation. Similar ideas on the favorable influence of small amounts 

 of stable manure have been expressed by Lipman and associates. 64 

 Their ideas were not confirmed by a careful analysis of the processes of 

 cellulose decomposition. It was found 65 that the favorable addition 

 of small amounts of stable manure is due to the nutrients, especially 

 the nitrogen that it contains. 



Nitrogen-fixation as a result of symbiotic action of nitrogen-fixing 

 and cellulose-decomposing bacteria, with cellulose as the only source 

 of energy, has also been demonstrated by other investigators. 66 Peat 

 is very resistant to the action of cellulose decomposing bacteria, but 

 this resistance can be overcome by preliminary treatment of the peat, 

 as boiling, steaming, or grinding. It is claimed that it may then 

 become a source of energy for nitrogen fixing microorganisms. 67 

 The importance of this process in increasing the supply of soil nitrogen 

 is, however, still questionable. 



Influence of soil conditions upon cellulose decomposition. The exist- 

 ence of thermophilic bacteria in the soil indicates that a high tempera- 

 ture is not injurious to cellulose decomposition but may even be 

 highly beneficial. According to Bertrand and Compton, 68 46° is the 



63 Koch, A. Die Luftstickstoffbindung im Boden mit Hilfe von Cellulose 

 als Energiematerial. Centrbl. Bakt. II, 27: 1-7. 1910; Jour. Landw., 55: 355- 

 416. 1907. 



64 Lipman, J. G., Blair, A. W., Owen, I. L., and McLean, H. C. The influ- 

 ence of bacteria supplied in manure on the decomposition of green manure 

 (legume and non-legume). N. J. Agr. Exp. Sta. 25th. Ann. Rpt.: 24S-260. 

 1912; 26th: 474-478. 1913; 27th: 223-226. 1914. 



65 Barthel, Chr., and Bengtsson, N. Action of stable manure in the decom- 

 position of cellulose in tilled soil. Soil Sci., 18: 1S5-200. 1924; Medd. No. 300, 

 Centralanst. forsoks. jordbruks. Bakt. avd. 40. Stockholm. 1926. 



66 Hutchinson and Clayton, 1918 (p. 195). Groenewege, 1920 (p. 436). 



67 Schmidt, E. W. Torf als Energiequelle fiir die stickstoffassimilierende 

 Bakterien. Centrbl. Bakt. II, 52: 281-289. 1920. 



68 Bertrand, G., and Compton, A. Influence de la temperature sur l'activite 

 de la cellase. Bull. Soc. chim. France, (4), 9: 100. 1911. 



