n6 RUBBER AND 



of rocks or other obstructions, or by excessive gradients. 

 Later on it is probably better to conserve the mulch of 

 fallen leaves and to imitate forest conditions as closely 

 as possible. 



With regard to the use of manures, no really reliable 

 experimental work has yet been published, and opinions 

 can only be based on general principles and on 

 .plantation experience. The latter shows considerable 

 unanimity in favour of the use of artificial manures 

 on the poorer classes of soils. Such manures, especially 

 those containing nitrogen and potash, are said to exert 

 a markedly beneficial effect on growth, yield and renewal 

 during the earlier stages of the life of the tree. The 

 application of potash is said to be specially beneficial in 

 connection with renewal of bark. Phosphorus is found 

 in practice to have less influence on the functions 

 named ; and this is what would be expected on general 

 agricultural principles, since the use of phosphates is 

 generally closely associated with the formation of seed. 

 The application of phosphates may therefore perhaps be 

 suggested in connection with seed-bearers. Manures 

 containing potash have the advantage of being consider- 

 ably cheaper than nitrogenous and phosphatic manures. 

 An excess of nitrogen is to be avoided, as it is said to 

 make the trees top-heavy and brittle. Such an excess 

 is well known to lead to an extravagant production 

 of foliage in the majority of plants. Apart from this, 

 it does not seem likely that the application of artificials 

 in moderate quantities can have any deleterious effect 



