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demand on the soil ; people generally wish to plant rubber and 

 nothing else, they do not care to be troubled with anything but 

 rubber trees, and they are prepared to wait for their returns from 

 such a cultivation. It cannot be doubted that there is something 

 in these contentions. 



What are the results which have been obtained with intercrops 

 in widely planted rubber ? Probably the most successful combi- 

 nation we know of at the present time is Cocoa and Rubber, 

 though tea and coffee deserve consideration. An estate planted 

 with rubber 20 x 20 feet and cacao 20 x 20 feet, possesses approx- 

 imately 100 trees, per acre, of each kind. The interplanted cacao 

 trees will probably give f to lib. of dried cacao each during the 

 fifth or sixth year, which, valued at an average price of about 60s. 

 per cwt. means that each tree only gives, in gross returns, about 

 4 id. to 6jd. of produce per year ; each rubber tree may, at present 

 prices, be expected to yield about 4 to 5 shillings worth of produce 

 at the same period. The fact that approximately ten cacao trees 

 will be required to produce the equivalent of a single rubber tree, 

 leads one to question whether it is financially sound to give up 

 such a large area of soil to such an intercrop, and many have 

 decided, on this ground alone, to plant their rubber trees closer 

 and elimate all intercrops. 



The occupation of such a large proportion of the soil by inter- 

 crops among the rubber, must lead to a certain amount of inter- 

 ference in root development of the rubber trees, and partial soil 

 exhaustion may be expected. Furthermore, such intercrops are 

 usually only transitionary, they do not last for very many years, 

 though the original expenditure in planting them is much the same 

 as when the intercrop is planted alone ; cocoa appears to be an 

 exception to a certain extent, as it lasts for many years under 

 widely planted rubber, if properly attended to. 



INTERPLANTING WITH HERBACEOUS AND ARBORESCENT 



SPECIES 



Lastly we are left to consider the interplanting of rubber 

 estates, no matter what distance the rubber plants are from one 

 another, with species which are of value for shading, manuring, 

 and other purposes. 



The broad casting of seeds of Crotalaria striata, Vigna species, 

 or i nterplanting the rubber trees with plants of Albizzia moluccana, 

 or cuttings or plants of Erythrina species (Dadaps) has been 

 frequently recommended for experiment. It is obvious that such 

 a system checks, to some extent, the loss of soil ingredients, the 

 ground is shaded during the various seasons, a more uniform con- 

 dition of soil temperature and moisture is maintained, the weeds are 

 kept in check, the roots of the plants break up the soil, and a 

 large amount of organic matter is available for manuring the 

 rubber plants. On the other hand, it can be argued that the inter- 

 planting of such species often interferes with the growth of the 

 roots of the rubber plants, the dense growth harbours por- 

 cupines, hares, pigs, and other rubber pests, large stumps of 



