Untreated 

 soil 



Partially 

 sterilised 

 by toluol 



Partially 

 sterilised 

 by heat 



Partially sterilised 

 by toluol 



Untreated Partially sterilised 



soil by carbon 



disulphide 



Fig. 1. Crops grown on untreated and on partially sterilised soil 



