Agriculture and Soils op the Cape Province. 42'.> 



THE AGRICULTURE AND SOILS OF THE CAPE 



PROVINCE. 



By Arthur Stead, B.Sc, F.C.S., Research Chemist, Grootfontein 

 School of Agriculture, Middelburg, Cape. 



I. 



Witkop— Burghersdorp. 



{The previous instalments of this article ap-peared in the May and 

 July 7ium,bers of tJie Journal.— Acf/r/^' Editor.) 



Over the spruit there is a turf-looking soil whose reputation for 

 fertility is better than that of the adjacent higher-lying Molteno 

 beds " zandbult " soil. Sample No. 613 was taken here. The 

 natural vegetation of the soil consists mainly of " zuurgras " ; but 

 here and there is to be found a plant of " blamvzaadgras." The 

 soil is probably alluvial to some extent, because in the spruit were 

 a number of dolerite boulders, washed down, presumably, from the 

 dolerite-capped red beds on Kalkfontein. At the time the sample 

 was taken the land was being prepared for potatoes, a crop to w^hich 

 the soil is said to be well suited. 



Before discussing the analytical figures of this report, it is 

 considered advisable in the interests of the general reader to devote 

 a few pages to a consideration of the several factors which are 

 concerned in the growth of crops, giving at the same time some 

 indication of the bearing of the analytical figures on the estimation 

 of the fertility of the soil and its suitability for particular crops. 



Factors in Plant Growth.* 



Six principal factors are concerned in the growth of crops. They 

 are : — 



1. Light. 



2. Temperature. 



3. Air supply. 



4. Water supply. 



5. Food supply. 



6. Harmful factors. 



The first five factors must all be present for growth to be possible ; 

 if any of these five factors is present to an inadequate degree only, 

 crop yields will suffer accordingly. 



Harmful Factors. — Should any harmful factor be present, the crop 

 yields will be below normal in proportion to the intensity of the action 

 of the harmful factor. Attacks by insect pests, diseases, and so on 

 are harmful factors capable of untold dama_ge to crops. For instance, 

 rust now prevents the wheat crop from yielding grain' in the 



* The foUowmo: remarks are based to a considerable extent on the admirable account 

 given by E. J. Russell, F.R.S., in "Soil Conditions and Plant Growth." 



