RUBBER PLANTING 95 



C is the "cabooky" soil at Henaratgoda, Ceylon, 

 analysed by Bruce. 



D is an analysis by Dyer of soil at Rothamsted 

 upon which wheat had been grown continuously for 

 fifty years without manure. The low percentages of 

 organic matter and nitrogen are to be associated with 

 the exhaustion produced by this continuous cropping. 

 Nevertheless this soil is still much richer in mineral 

 constituents than either of the three examples of 

 tropical soils. Even the Malay soil, rich as it is in 

 organic matter and nitrogen, is very poor as regards 

 phosphoric acid, and by no means rich in potash. In 

 spite of such deficiencies the warm moist climate of 

 the tropics gives rise to an abundant growth of vege- 

 tation. 



In short, it may be asserted that Hevea can be 

 grown to a profit on almost any soil in the latitude 

 of Ceylon up to an elevation of 2000 feet, provided 

 the rainfall exceeds 75 inches a year, and provided a 

 situation is chosen which is not exposed to strong 

 winds, especially at the dry season of the year. On 

 the other hand, the richer the soil and the lower the 

 altitude the better, provided that on swampy lands 

 good drainage be provided. The best test of a soil 

 much better than the test of chemical analysis is the 

 character of the vegetation growing upon it. If the 

 growth of forest over a given area is luxuriant, other 

 conditions being favourable, then a good growth of 

 rubber is assured when the forest is cleared. And if 



