SOIL ORGANISMS 413 



blood was ammonified more rapidly than was cottonseed meal, 

 while in other soils the reverse was true. 



While the soil fungi have been but little studied, the litera- 

 ture available seems to indicate that they take an important 

 part in all soil processes, except possibly the fixation of at- 

 mospheric nitrogen and the formation of nitrates. Most soil 

 fungi produce ammonia readily. Waksman x found such 

 forms as Mucor racemosus, Pencillium lilacinum, and Bhiz- 

 opus sp. II compared, favorably in capacity to produce am- 

 monia with Bacillus mycoides when grown in artificial cul- 

 ture, blood and cottonseed meal being the sources of nitrogen. 

 Kopeloff 2 found that certain fungi seemed to prefer an acid 

 medium for their ammonifying activities. This suggests that 

 a natural provision is thus made for ammonification, no mat- 

 ter what the soil reaction may be. 



Among the bacteria producing ammonification are B. my- 

 coides, B. subtilis, B. mesentericus vulgatus, B. janthinus, 

 and B. proteus vulgaris. Of these, B. mycoides has been very 

 carefully studied, and the findings of Marchal 3 may be taken 

 as representative of the process of ammonification. He found 

 that when this bacterium was seeded on a neutral solution of 

 albumin, ammonia and carbon dioxide were produced, to- 

 gether with small amounts of peptone, leucine, tyrosine, and 

 formic, butyric, and propionic acids. He concludes that in 

 the process atmospheric oxygen is used, and that the carbon 

 of the albumin is converted into carbon doxide, the sulfur 

 into sulfates, and the hydrogen partly into water, and partly 

 into ammonia by combining with the nitrogen of the organic 



1 Waksman, S. A., Soil Fungi and Their Activities; Soil Sci., Vol. 

 II, No. 2, pp. 103-155, 1916. See also, McLean, H. C, and Wilson, 

 G. W., Ammonification Studies with Soil Fungi; N. J. Agr. Exp. Sta., 

 Bui. 270, 1914. 



a Kopeloff, N., The Effect of Soil Beaction on Ammonification by 

 Certain Soil Fungi; Soil Sci., Vol. I, No. 6, pp. 541-573, 1916. 



3 Marchal, E., Sur la Production de VAmmoniaque dans le Sol par 

 les Microbes; Bulletins de PAcad. Koyale de Belg., 3 series, T. 25, pp. 

 727-776 j 1893. 



