KARROO SOIL, LUCERNE AND THE OSTRICH 

 FEATHER. 



IBy Professor Paul Daniel Hahn, M.A., Ph.D., and the late 

 Donald Sinclair Stevenson. 



The first analyses of soils in the Cape Colony were made 

 in 1879 and 1880. These investigations were, however, 

 limited to vineyard soils in the south-western part of the 

 Colony. The results revealed the fact that there was a re- 

 markable difference in the principal features of the vineyard 

 soils of the coast districts and the inland districts. The 

 former, mostly stiff clays, which were formed by the disintrega- 

 tion of metamorphic slate, of granite, or of both, are poor, 

 very poor, in lime, but do not require irrigation during the 

 summer season, whereas the vineyards of the inland districts 

 are on a porous, loose loam, which is fairly calcareous; the 

 grapes in these vineyards do not come to perfection unless 

 the ground has been irrigated two or three times during the 

 summer season. These investigations were made in connec- 

 tion with the work of the first Phylloxera Commission. The 

 report of this Commission includes an interesting sketch-map 

 showing the districts of the Colony which had clay and lime 

 soils. 



After the establishment of the Agricultural Department the 

 analyses of the soils in the agricultural districts of the Colony 

 was vigorously taken up by Dr. C. F. Juritz, who published 

 in 1909 the results of his own and his associates' labours in one 

 volume, the study of which is most instructive. It is an 

 excellent work and full of valuable information. I only 

 regret that the matter of the book is not arranged according 

 to some scientific principle, such as the geological structure of 

 the country, but in alphabetical order of the districts. It so 

 happens that the report on the soils of the Oudtshoorn dis- 

 trict is followed by the report on the soils of the Paarl dis- 

 trict. I recommend to the reader the study of these two 

 reports and the analyses given, which show in a striking 

 manner the contrast which exists between the two principal 

 kinds of soil of the Colony : the stiff clay soil, formed from 

 clayslate, or granite, or both, and poor in lime and other 

 plant-food, and the loose Karroo soil — frequently an alluvial 

 soil — abounding in plant-food and particularly in calcareous 

 ■constituents. 



On the former we have frequently the sour veld, and on 

 the Karroo soil the sweet veld. There are of course many 

 varieties of each of these principal soils, and in a dry 

 ■climate like ours " brack " plays an important part in the com- 

 position of the soils. 



The farmer in the Karroo district attaches much importance 



to the occurrence of the Mimosa or Thorn-Tree (Acacia 



horrida), which is a sure indication of rich and deep soil. If 



w^e examine the composition of the mineral ingredients of this 



"tree we come to the conclusion that it can only grow on a 



