16 THE RUBBER TREE BOOK 



many to be excretory, although this is denied by other chemists 

 invariably affects the second crop. This is one of the reasons 

 why crop rotation is found so desirable by farmers. Fortu- 

 nately, good drainage, cultivation and the addition of lime will 

 improve almost any soil, just as bad drainage and neglect of 

 cultivation will cause soils to deteriorate. There is good reason 

 for coming to the belief that the character of the bacteria 

 present in the soil becomes altered when the lime contents are 

 reduced below a certain limit and the organisms which prey 

 upon them become unduly multiplied. 



The rubber planter having thus realized that the soil is not 

 a mass of dead material, but although the surface may appear 

 to the limited range of our eyesight bare is yet covered and 

 intermingled, to a depth of several feet in many cases, with 

 millions of minute plant organisms upon whose healthy exist- 

 ence his crops must ultimately depend, intelligent cultivation 

 should surely follow as a matter of course. 



