Foundation of Soil Microbiology 



11 



The use of legumes for enriehment of the soil was knowu to the 

 ancient Romans. Berthelot was the first to suggest that nitrogen 

 fixation may be accoinphslicd also l^y uonsymbiotie l)acteria. The 



Fig. 6. Louis Pasteur established the role of microorganisms as causative agents 

 of diseases and fermentations. 



organisms concerned both in nitrification and in nitrogen fixation 

 were not isolated until toward the close of the last century. 



Thus, the work of the bacteriologists and chemists, of plant physi- 

 ologists and agricultural chemists, contributed to the understanding 

 of the cycle of life in the soil and laid the foundation for soil micro- 

 biology. Microbes, especially bacteria, were found to occur abun- 



