416 



THE FERTILITY OF SOILS IN THE TROPICS 



These lands are characterized by being very clayey but 

 containing a considerable quantity of organic matter, 

 rendering them almost black in appearance. They are 

 well supplied with nitrogen, and with potash and phos- 

 phate, both in the total and " available " forms. 



Observations go to show that if badly drained they are 

 infertile; but that for coconuts the drainage need be 

 less deep and thorough than for rubber. 



Instances can be pointed to in which coconuts and 

 rubber are growing side by side, the former yielding 

 magnificently, the latter hardly at all. 



Inland the tree seems to prefer a soil of good open 

 texture just as does Hevea, and on the heavy clays 

 yields are poor, only twenty to thirty nuts per annum. 



The writer has not yet had an opportunity of visiting 

 or examining any of the east coast soils, on which the 

 tree is reputed to give phenomenal yields when growing 

 apparently in pure sand. Such very sandy soils as have 

 come under notice have been associated with extremely 

 low yields, unless heavily manured. 



The following percentage analyses represent some of 

 the best west coast soils : 



Coarse sand 

 Fine sand 

 Silt 



Fine silt 

 Clay 

 Humus 



Nil 

 10-9 

 25-2 



21-4 

 7 '4 



Mechanical Analyses. 



Chemical Analyses. 



It is not possible to draw comparisons between these 

 soils; as far as estimate is possible, owing to different 



