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THE PROBLEM OF MANURING IN CONNECTION 

 WITH THE CULTIVATION OF THE PARA 

 RUBBER TREE. 



The question of the application of artificial fertilizers in the culti- 

 vation of the Para rubber tree is closely connected with the value of 

 plantation Para rubber and the yield. 



Manurial treatment which would be profitable with a product 

 yielding a profit of $1.50 per pound might not be so with rubber at a 

 profit of 50 cents or less per pound. 



It can be safely asserted that no agricultural product either in 

 temperate or tropical countries at present yields such a handsome 

 return on expenditure. 



This state of affairs is not without its attendant disadvantages, 

 as with such a handsome profit as say $1.50 to $2 per pound of rubber, 

 there is a tendency in many cases to underrate the value of obtaining 

 an extra profit, either by preparing better rubber or by increasing the 

 yield, which may one day represent the difference between success and 

 failure on an estate. In connection with the question of increased 

 yields by cultivation or the application of manures the same remarks 

 apply. 



Manurial treatment costing say $30 per acre would be justified by 

 any increase of yield of rubber per acre over and above an increase of 

 20 lbs. per acre with rubber yielding a profit of $1.50 per pound, i.e., 

 an increase of 10 per cent, on a yield of 200 lbs. per acre, whereas with 

 rubber yielding only half this profit an increase of more than 40 lbs. 

 of rubber per acre, i.e., an increase of over 20 per cent, would have to 

 be obtained to justify a similar expenditure under such circumstances. 

 This applies to the output for one year only — a smaller increase 

 extended over two or more years would equally justify the application 

 of manures at the above cost. 



The value of various agricultural products in most cases may be 

 stated to have reached a level, with only occasional fluctuations due 

 to shortage or other causes, so that the profits are more or less fixed. 



It is extremely probable however — one might almost say cer- 

 tain — that the normal level of price has not yet been reached in the 

 case of rubber, and till this is so, the question of extra expenditure on 

 cultivation and manuring is by no means an easy problem except in 

 special cases. 



An illustration of how not to conduct such manurial treatment 

 was recently brought to my notice by seeing an advertisement in this 

 country of a certain fertilizer of which a planter had applied 20 lbs. 

 per tree. Assuming even only 100 trees per acre this would mean 

 about 2000 lbs. per acre or say I ton per acre, costing in this particular 



