THE PROBLEM OF MANURING IN CONNECTION 
WITH THE CULTIVATION OF THE PARA 
RUBBER TREE. 
The question of the application of artificial fertilizers in theculti- 
vation of the Para rubber tree is closely connected with the value ot 
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 rub >er 
there is a tendency in many cases to underrate the vame of obtaining 
an extra profit, either by preparing better rubber or by increasing the 
yield, which may one day represent the difference between success an 
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 ot 
20 lbs. per acre with rubber yielding a profit of $1.50 P-’r 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 cncumstances. 
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 oriels 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 m till 
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 
