THE GERM LIFE OF THE SOIL 



127 



take in soil fertility some further description of their oc- 

 currence in soils will be given. 



156. Numbers of bacteria in soils. — It is naturally to 

 be expected that soils differ greatly in the number of bac- 

 teria that they possess. Where there is a large amount of 

 easily decomposable organic matter,- the number is great, 

 and consequently in rich garden soils that have been heavily 

 manured, or where the carcasses of animals have been buried 

 the bacterial flora is dense. On the other hand, in very 

 sandy soils, desert soils and water-logged soils, bacteria are 

 few in number. 



While there are usually many bacteria in fertile soil, it is 

 not always the case that there are more in such soils than 

 in less productive ones. The number of bacteria that a 

 soil may contain cannot be considered a measure of its pro- 

 ductiveness. The numbers of bacteria found in one gram 

 of soil of different kinds and treated in different ways are 

 given in the following table : 



Table 29. 



-Number op Bacteria to a Gram op Soil During 

 Some Period of the Growing Season 



