t7 6 



" Potash, one of the chief mineral constituents required for 

 plant growth, is frequently deficient, though a few of the river 

 deposits are rich in this constituent, and the subsoil is usually 

 richer than the surface soil especially if of a clayey nature. 



" The proportion of phosphoric acid is also variable, ranging 

 from 0.012 to 0.13, the average being about 0.76 per cent, on the 

 air-dried soil. 



"All this class of soil requires very efficient drainage as it 

 has often been more or less under water for years, so that air 

 has been excluded, resulting in a rather high proportion ot he 

 lower oxide of iron, which in excess is poisonous to many culti- 

 vated plants. The vigorous growth of rubber on this class 

 soil after drainage is unequalled elsewhere during the first years 

 of growth. 



" Upland Soils.— These soils have a larger P ro P ortio " ° f 

 sand and coarser particles in their composition which renae 

 them more open, and drainage, except for saving wash, les* 

 necessary. 



" They are richer in nitrogen than the proportion of organic 

 matter would indicate, but are usually a little deficient in totai 

 potash and to some extent in phosphoric acid. 



" Their free character and suitability for root growth makes 

 the proportion of these constituents ample for present requ 

 ments, and it is evident from the growth of Para on these 

 that there is no deficiency in any respect. 



