It should be remembered that on the lalang grounds 

 of Deli, only tobacco has been grown and consequently 

 there has been no denudation from the rains, so that 

 there is not an exact parallel between these and the 

 old Cassava plantations of the Malay Peninsula. 



c. Soils in which other crops are grown. 



Finally there are some cases to be discussed where other 

 vegetation than the foregoing has to give place to Hevea 

 usually this is coffee. On the East Coast of Sumatra this 

 is still often the case, but in the Malay Peninsula it is not so 

 common now (see fig. 5). Hevea is frequently interplanted 

 with Liberian coffee. In such cases there should be no 

 hesitation about cutting the coffee back vigorously where 

 it encroaches on the Hevea (see fig. 6). Otherwise 

 the rubber grows but slowly while it stands between 

 the coffee, and only increases to any degree after its 

 crown has overtopped the coffee. Experience has taught 

 Straits planters that Hevea needs plenty of sun. I have 

 seen several Hevea plantations in the native states 

 interplanted with coffee. Although the girth of the rubber 

 trees may be somewhat less than trees of the same age 

 planted on jungle ground, the production of latex was quite 

 as good. It must be taken into consideration that coffee 

 crops are obtainable for some years during the growth 

 of the rubber, although they are of course a decreasing 

 quantity as the Hevea grows. Furthermore there is the 

 advantage that the ground remains covered and mainte- 

 nance accordingly is less, whilst there is an absence of 

 fungus. 



Sumatran experience is similar, I have seen several 



