Soil Microbiology as an Independent Science 21 



and correlated \\ ith erop yields, the arbitrary conditions of the tests 

 were found to limit their value, and the methods have now been 

 largely abandoned. 



The appearance in 1910 ot Lohnis" monumental work, Ilandbiich 

 der landwirtschaftlichen Bakteriologie, tended to summarize the 

 developments in this subject and to point a way to futiue investiga- 



FiG. 14. Jacob G. Lipnian first initiated in tlie United States a comprehensive 

 study of the microbiological population of the soil and its role in soil processes. 



tions. This book was followed in 1911 by Lipman's somewhat dif- 

 ferent volume, Bacteria in Relation to Country Life. 



Soil Microbiology as an Independent Science (1911-1940) 



The thirty-year period from 1911 to 1940 brought forth extensive 

 developments in the field of soil microbiology. Particular emphasis 

 was laid not only on the bacterial population of the soil, but also on 

 the other groups of microorganisms inhabiting the soil, notably the 

 fungi, actinomycetes, algae, protozoa, nematodes, and insect larvae. 

 Attention was also focused upon the complex interrelationships among 

 the various groups of microorganisms and their significance in soil 

 fertility. 



