HISTORY OF SOIL MICROBIOLOGY 843 



3. Transformation of organic matter in the soil, both as to the 

 chemical processes involved and organisms concerned, also the role 

 of these transformations in soil fertility. 



4. The energy balance in the soil as well as the balance between 

 the soil constituents, largely the carbon and nitrogen. 



5. A better understanding of the role of cultivated higher plants 

 in soil transformations and the influence that they exert upon the 

 activities of soil microorganisms. 



6. Methods of modifying the soil population and its activities with 

 a better understanding of the processes of partial sterilization, applica- 

 tion of lime and fertilizing materials, soil inoculation, as well as soil 

 fallowing. 



7. The physical, chemical, and physico-chemical condition of the 

 soil (reaction, buffer content, moisture holding capacity, temperature) 

 and the occurrence and activities of soil microorganisms. 



These as well as a host of other problems to which attention has 

 been called in the previous pages will not only throw light upon the 

 different phases of soil microbiology, little understood at the present 

 time, but will place the science where it should be, namely in the 

 front rank of agricultural sciences. 



Depending as he does upon the contributions of the protozoologist, 

 mycologist, bacteriologist, nematologist, etc., for a better understand- 

 ing of the organisms inhabiting the soil and their activities, the soil 

 microbiologist is in a position to correlate the sum total of the knowledge 

 gained from these investigations and throw light upon the chemical 

 processes in the soil. The soil physicist and the soil chemist do and 

 will contribute definitely to the understanding of the nature of the 

 medium in which these organisms act and of the soil solution, which 

 receives, on the one hand, the waste products of their activities and 

 which supplies nutrients to the plants and frequently to the micro- 

 organisms. It is to the development of the science of soil microbi- 

 ology as much as to any other science that we must look for the 

 proper understanding of the soil as to its ability to supply the 

 nutrients necessary for the growth of higher plants 5 



5 Further information on the history and development of soil microbiology is 

 found in the following papers and books: Fischer, 1909 (p. 712); Lohnis, 1910 

 (p. xiii); Lohnis, F. Ergebnisse amerikanischer, britischer und franzosicher 

 Arbeiten auf dem Gebiete der landwirtschaftlichen Bakteriologie aus den Jahren 

 1915 bis 1920. Centrbl. Bakt. II, 54: 273-307. 1921; Winogradsky, S. La 

 m^thode directe dans l'etude microbiologique du sol. Chimie et Industrie., 

 11: No. 2. 1924; Waksman, S. A. Soil microbiology in 1924; an attempt at an 

 analysis and a synthesis. Soil Sci., 19: 201-249. 1925. 



