(7) 



I)e.}|j(ii'jjji{ ■ 

 ■ifffiol) lo rf' 



^■!the feetility of some colonial soils, as 

 r' influenced by geological conditions. 



By Chas. F. Jueitz, M.A., F.I.C., 



Senior Oovermnent Analyst. 



^"' (Eead at a Meeting of the S.A. Philosophical Society held on 



March 27, 1907.) 



About seven years ago it was my privilege to read before this 

 Society a paper embodying some results of investigations made in 

 the Government Analytical Laboratory with regard to the pro- 

 portions of plant food in a number of soils collected within the 

 South-western Districts of the Colony.''' I then endeavoured, as far 

 as available information would permit, to refer each sample analysed 

 to the underlying geological formation, with a view to deducing such 

 conclusions as it would be permissible to draw respecting certain 

 phases of the agricultural capabilities of soils derived from this or 

 that series of rocks. It was at that time found practically impossible 

 to suggest any deductions in respect to the relationship between the 

 geology of a district and the agricultural potentialities of its soils, 

 based upon the results of chemical analyses of the latter, which 

 could not have been equally well arrived at by comparing the 

 geological features with nothing more than the practical experience 

 of local agriculturists. Family resemblances between soils over- 

 lying one and the same series of rocks were not sufficiently evident, 

 and, as far as the investigations in the Government Laboratory had 

 proceeded, similarities between soils were apparently due more to 

 geographical than to geological causes. 



The reasons for this will become clearer as we proceed, but for the 

 present they may be summarised in two words — insufficient data. 



It is an essential preliminary to an adequate comprehension of the 

 figures which I propose to place before you that I should explain 

 precisely what is meant by the term ''soil analysis" as employed 

 and implied in this paper. The expression has a variety of significa- 

 tions ; hence it is not surprising to find that it has been subjected to 

 much misuse, as the operations it represents have been to much 

 ,«iJOiydo a^m^^rrj^^ans. S.A. Phil. Soc, vol. xi., pt. 2, pp. 125-160. 



