Fertility of some Colonial Soils. 29 



They show considerable variety, both in texture and in chemical 

 composition. The proportions of lime, potash, and phosphoric oxide 

 average as follows : — 



Lime '584 



Potash -153 



Phosphoric oxide '106 



I append, in tabular form, a summary of the average results 

 obtained from the various types of soil reviewed during the course 

 of these remarks; this may serve to bring out more clearly the 

 characteristic differences in respect of plant food. The average 

 amounts of water contained in each class of soil when air-dry have 

 also been added ; the low water-retentive capacity of the soils of the 

 Malmesbury and Table Mountain series will be noted, as also the 

 large amounts of moisture retained by the Upper Karroo soils of 

 the Burghersdorp-Stormberg type. 



Geological Formation. 



Number 



of Soils 



Analysed. 



Water. 



Lime. 



Potash. 



Phos- 

 phoric 

 Oxide. 



Pre-Cape Rocks ... 



Malmesbury series 



Granite 



Campbell Rand series... 

 Olive shales 



14 

 9 

 7 



21 



46 

 18 



11 

 4 



2 



24 

 21 



2 

 11 



•94 

 119 

 3-99 



208 



1-08 

 1-27 



•93 



3'49 



2-44 

 4^29 

 1-44 



2^86 



•039 



•049 



4-169 



•310 



•034 

 •387 



•042 

 ■051 



1013 



•233 



•299 



•078 



•584 



•039 

 •069 



•048 

 •067 



•031 

 •231 



•141 



■058 



•138 

 •172 

 •181 

 •030 

 •153 



•039 

 ■048 

 •057 

 ■051 



Cape System - 



, Table Mountain series 

 Bokkeveld series 



•036 

 •118 



Common horizon of 

 Table Mountain and 



Bokkeveld series 



^Witteberg series 



Dwyka series 





Karroo System 



Cretaceous System. 

 Recent deposits ... 



•075 

 •065 



•059 



Burghersdorp beds and 

 Stormberg series 



..Uitenhage series 



Sand Downs 



•078 

 •087 

 •027 



■ Alluvial silts and river 

 deposits 



•106 







In placing these results of some of our work before you, I must 

 again express my sense of their meagreness. These investigations 

 have now been in progress for some twelve years, or rather, they 

 were started twelve years ago, but it must be confessed that, when 

 the period of time is taken into account, there is very little to show. 

 The Director of the Geological Survey of the Colony, in his Eeport 

 for 1904, remarks that, at the rate his work of mapping the Colony 

 geologically is progressing, the task will take over thirty years to 

 complete. I have a similar plaint to utter, but on our side a century 

 will probably be the minimum limit, unless an earnest attempt be 

 made to tackle one of the most important investigations that can be 

 undertaken in the interests of the country's agriculture. 



