PARA RUBBER. 27 



and thus makeroom for the further development of the remain- 

 ing plants. It should be mentioned that there are trees which 

 have been grown in moderately rich soil for over twenty years , and 

 though they are still only from eight to ten feet apart they have a 

 circumference of from forty to over eighty inches, and a branch and 

 foliar system measuring less than thirty feet in diameter. I have 

 frequently seen Para trees which, though planted the same distance 

 and over 10 years old, did not appear to be too crowded. 



Close Planting and Available Tapping Area. 



The main justification for closely planting Para rubber trees is 

 the increased tapping area which is available from the fourth year 

 onwards ; the disadvantages are in connection with the spreading 

 of diseases, and possibly checking the growth by not thinning-out 

 at the proper time. 



The object of most persons who are only just planting this pro- 

 duct is to place their rubber on the market as early as possible, in 

 order to benefit by the high prices and to obtain quick returns. The 

 results obtained by close planting can be made clear by calculat- 

 ing the available tapping area from the data previously given. 

 The table given below shows the tapping area per acre when the 

 plants are distanced from 10 to 20 feet apart : — 



Available tapping Area 

 per Acre at the End of 

 Distance of Trees Number of Trees the 4th or 5th Year 



in Feet. to the Acre. in Square Inches ; 



Base to 5 Feet. 

 10 by 10 . . 435 . . 522,000 



10 by 15 . . 290 . . 348,000 



20 by 20 .. 109 ... 130,800 



From this table it is obvious that by planting 20 by 20 feet the 

 available tapping area at the end of the 4th or 5th year is reduced 

 to about one-quarter of what it would be if planted 10 by 10 feet. 

 On an estate planted 10 by 10 about 5 per cent, of the trees could 

 be killed out at the end of the 4th year, and a larger proportion 

 dealt with likewise in succeeding years, until by the end of the 8th 

 year an average of about 250 trees per acre would remain. 



The distance of 10 feet by 10 feet suggested on the above 

 calculations is still open to the objection that the soil will be consider- 

 ably exposed during the first few years, but this can be overcome by 

 the interplanting of cuttings or plants of Erythrina lithosperma 

 (Dadap), a species which can be made to afford shade for the first 

 few years and at the same time provide a rich mulch for the bene- 

 fit of the young Para rubber plants. 9 



On several estates the rubber trees have been planted 8 by 8 feet 

 and even closer, on the assumption that half of them would die from 

 one cause or another or could be cut out when the growth became 

 too dense. 



