THE FERTILITY OF SOILS IN THE TROPICS 365 



accumulation of organic matter affords an explanation 

 of the high fertility typical of newly cleared forest land 

 in the tropics, since considerable accumulations of nitro- 

 gen are apparently likely to take place as the result of 

 the action of nitrogen-fixing bacteria, while the reserves 

 of other plant foods remain undepleted. 



Tne question of the relationships existing between the 

 content of organic matter, the bacterial population, and 

 the fertility of tropical soils is of considerable interest; 

 owing to the high and equable temperature the various 

 processes are enabled to proceed with much greater 

 regularity and at a much higher speed than under tem- 

 perate conditions. Considerations such as these indicate 

 that the tropics present special facilities for the study 

 of certain soil problems and it would seem that the further 

 investigation of the subject would be likely to yield in- 

 formation of value and facilitate the elucidation of 

 important points which are at present obscure. 



