434 SOIL FUNGI 



unsterilized soil, so that the application of Coleman's findings to 

 conditions in the field is difficult or even impossible of accom- 

 plishment. 



Waksman (1922) applied several treatments to soils to determine 

 their influence upon the numbers of fungi and obtained the results 

 shown in Table 31. 



Ammonium sulphate and lime 6.2 39,100 



In general, it would be expected that soils rich in organic matter 

 would support the most abundant fungus population. Jensen 

 (1931) is among those who hold this belief, for he concluded that 

 the application of barnyard manure to soils results in increased 

 numbers of fungi. 



The kind of organic matter, through its correlation with the 

 kind of cleavage products resultant from decomposition, may 

 well be a factor of consequence in determining the kind of fungi 

 that predominate. Species of Penicillium and Trichoderma were 

 noted by Jensen (1931) to prevail in acid soils. In this instance 

 carbohvdrates may have constituted the source from which the 

 acids were derived. On the other hand, Jensen (1931) also made 

 the observation that My co gone nigra and Coccospora agricola 

 prevailed in alkaline soils that may be assumed to have derived 

 their alkalinity bv ammonification of proteins. 



BIOCHEMICAL ACTIVITIES OF SOIL FUNGI 



The purpose of this discussion is to stress the role that soil fungi 

 play in the transformation of organic matter into humus and into 

 other material necessary for the nutrition of green plants. The 

 impact of bacteriologic study and teaching has resulted in estab- 

 lishing the impression that bacteria constitute the organisms most 



