MANURING 61 



Calculations have been made showing the large amount 

 of phosphates annually carried away by the cacao crop, 

 and deductions from these figures have been drawn to 

 show that the necessary supply must in the end run short, 

 and that the lands will become barren unless it is artificially 

 supplied. 



Such conclusions are probably based upon an insufficient 

 knowledge of the conditions actually existing, for it is 

 a fact that there are now estates which have been con- 

 tinuously cropped for fifty years or more, without any 

 apparent diminution in the production of the trees. It 

 has, therefore, been shown that the phosphates are either 

 in the land, or are supplied to the land in some way not 

 as yet generally recognised — such as an incidental incre- 

 ment of plant-food furnished by agencies coincident with 

 animal and plant life. The annual loss of phosphates 

 when stated in tons appears to be large, but when the 

 annual loss per tree is shown as being somewhat over 

 three drachms, it does not then appear so formidable a 

 proposition, as it could clearly be supplied by the existing 

 animal life. If, however, crops can be increased by the 

 application of phosphates, it would tend to show a further 

 want of this constituent ; but if the crop is not increased 

 it would be strong evidence that sufficient is at hand, a 

 point which can easily be proved by a suitable course of 

 field experiments. 



Well-made farmyard manure is, however, well adapted 

 for the cacao estate, especially if sufficient animals can be 

 kept to maintain a constant supply. 



Cacao-planting and stock-farming are industries which 

 can be profitably run side by side, as the manure from 

 the latter — now practically wasted in many colonies — 

 could be utilised for increasing the output of cacao to an 

 extent not as yet fully realised. 



There can be no doubt whatever that the natural 

 incidental increment of plant-food is very high in the 

 western tropics, and must be considered on quite a different 

 basis to the conditions existing in temperate climates. 



