21 



soil together. The amount of earth lost from erosion is 

 larger than might be thought; it would cost some 

 hundreds of dollars per acre simply to replace by manure 

 the mineral matter washed away every year with the 

 surface soil. 



On the highland coffee plantations of Java this expe- 

 rience has been dearly paid for in early years of the 

 industry. Although coffee is different from Hevea, it is still 

 necessary with the latter to avoid from the beginning 

 the loss of the most valuable part of the estate the 

 surface soil. 



