24 PRESIDENTIAL ADDRESS SECTION B. 



be said to have given, within a brief compass, an illuminating 

 reView of the present-day phases of an ever-developing and ever- 

 progressing industry, no longer a gamble for sudden and for- 

 tuitous wealth, but now a fine example of the strenuous applica- 

 tion of science by man in his endeavour to earn an honest liveli- 

 hood. In short, gold-mining on the Rand has become a settled 

 industry, as settled as agriculture, although in many respects the 

 conditious under which these industries are practised are widely 

 different. 



•In dealing with the question of soil analysis, the chemist is 

 Struck by the contrast between the attitude of the farmer towards 

 chemical analysis in general compared with that of the miner 

 towards assaying. The agriculturist is in most cases content to 

 proceed in his own way and, in most countries, not merely in 

 South Africa, frequently this means that he takes little or no 

 account of chemical analysis. The miner, again, or, to be more 

 precise, the metallurgist, continually employs most exact chemical 

 methods for testing his ore and the various products derived 

 from it. The position of the prosperous farmer appears to be 

 that he does not see the need of analyses when he can get on well 

 enough without them. On the other hand, when crops fail and 

 the earth does not yield an increase, it is easy for the farmer to 

 lay all the blame on some cause, drought for instance, which may 

 plausibly be considered a matter beyond human control. No 

 doubt there are occasions when the most capable and progressive 

 farmer has reverses of a serious nature. With regard to drought, 

 it may be as well to recall the remarks made by Ingle * : — 



" In some countries of limited rainfall it is found that the crop which 

 can be raised from soil extending over large areas is mainly conditioned 

 by the amount of water which the plants are able to get rid of by trans- 

 piration from their leaves, and this in turn depends chiefly upon the 

 amount and distribution of the local rainfall during the period of growth. 

 If. however, one soil is richer in plant food than another, it will be able 

 to simply a crop with sufficient nutriment with the consumption of much 

 less water than would be necessary for the same yield in the case of the 

 second soil. Thus the maintenance of a sufficient supply of plant food 

 in the soil may be of more importance in countries of limited rainfall than 

 in wetter climates." 



The question then arises. What constitutes this sufficient 

 supply of phut food in South Africa for any particular crop in 

 any given soil ? How is the soil-chemist to answer this question 

 It is true that we have at our disposal, thanks chiefly to Dr. 

 Juritz in Cape Colony, and to Mr. Ingle in the Transvaal, a certain 

 amount of valuable information. Dr. Turitz's book, "A study 

 of the Agricultural Soils of Cape Colony," teaches us that the 

 virgin soils of the more humid districts of Cape Colony are 

 usually poor in plant-food, as judged by European standards, 

 while Mr. Ingle's papert indicates that the same general statement 



* " The Soils of the Transvaal from their Chemical Aspect," B. Ass. 

 Rep., 1905, p. 118. 



1 Brit, and S. Afr. Assns. for Adv. of Sc. Reports, iqo^, vol. i., 

 pp. 115-152. 



