The Golden Age of Soil Microbiology 



17 



by Winogradsky in 1891, and by Winogradsky and Beijerinck in 1893 

 and 1901. 



The fixation of nitrogen by the association of bacteria and legu- 

 minous plants formed an important chapter of its own which was 

 begun in the previous period and which has continued to the present. 



Fig. 10. S. N. Winogradsk>' first isolated in pure culture the bacteria concerned 

 w itli the processes of nitrification and nitrogen fixation, and later made a com- 

 prehensive study of the microbiological population of the soil. 



The brilliant contributions of the earlier investigators were followed 

 by numerous studies that led to the solution of this important prob- 

 lem, which has a significant bearing upon microbiology, plant physi- 

 ology, and agronomy. 



Among the most interesting investigations carried out during this 

 period should be listed the attempts to coordinate the activities of 

 bacteria with soil fertility. It was believed that a full appreciation 

 of this relationship not only would modify our outlook upon soil 

 economy, but also might revolutionize the whole agricultural prac- 

 tice. The agriculturist, as typified by Caron in 1895, believed that 

 knowledge of the soil bacteria would do for soil management what 

 knowledge of disease-producing bacteria had done for medicine. 



