Establishment and Tending of Timber Plantations 149 

 (2) Soil. 



A careful examination of soil conditions, especially where the 

 rainfall is on the low side, is very important. 



Generally the soils in forest areas and areas of high rainfall 

 where afforestation is most feasible are poor in plant food, being 

 especially lacking in lime and phosphoric acid. On account of 

 the deficiency of lime, locally described as " sourness," these 

 soils have to be very thoroughly worked before they can be planted 

 successfully. Fortunately the chemical composition of a soil has 

 little effect on tree growth, and there are few soils too poor in 

 plant food to sustain trees. The physical properties of a soil, 

 viz., its depth, porosity and a proper degree of moisture, especially 

 depth, are, however, of paramount importance in affore- 

 station. Depth of soil varies rapidly even within limited areas, 

 and stretches of land which present a uniform appearance to the 

 eye may show variation in depth from a few inches to several 

 feet. On accoupnt of the long dry season depth of soil becomes 

 a factor of prime importance, and is one of the cardinal points 

 to be considered in deciding on the suitability of any area for 

 planting. Hardpan, or impervious pot-clay subsoils occur over 

 large tracts, and render many localities, otherwise suitable for 

 tree growth, of little or no value for that purpose. The depth 

 of the soil and nature of the subsoil should therefore be carefully 

 ascertained by examining any railway cuttings, quarries, dongas 

 or sluits that may happen to be situated in or in the vicinity of the 

 area, and whenever in doubt test pits should be sunk. Trees 

 often flourish for a number of favourable years even on shallow 

 soil, and then go off suddenly, and the error of planting in such 

 ground may therefore not be discovered for some years. Generally 

 speaking a depth of 4 to 5 feet will be found sufficient, although 

 a lesser depth may suffice in areas of high rainfall. 



The soils most suitable for afforestation appear to be those 

 derived from granites. Table Mountain Sandstone and dolerites, 

 but it may be stated that some trees thrive equally well on soils 

 of the most different geological origin. 



