380 SCIENCE IN AFRICA 



It is not intended to suggest that Africa is becoming overpopu- 

 lated, but simply that the population is becoming too concentrated 

 in certain areas for the primitive method of shifting cultivation. 

 In other parts there is danger in the artificial stimulation of native 

 production for export, which increases the amount of land under 

 cultivation and so adds to the strain on its fertility. The dangers 

 of the situation are fully realized by all agricultural departments, 

 and in some areas efforts are being made to prevent its intensifica- 

 tion by the two obvious methods of (i) redistribution of population 

 and (ii) improvement in methods of native cultivation. 



Some native agricultural systems include methods of protection 

 against soil erosion. The primitive pagan cultivators of the plateau 

 in Northern Nigeria pick stones from gently sloping land and 

 arrange them in rows along the contours, so that soil wash is held 

 up and the whole area of cultivation becomes terraced automati- 

 cally. The same result is brought about by different means in 

 some densely populated parts of Kigezi in Uganda (Thomas and 

 Scott 1935, p. 117). On the steep cultivated hill-sides terracing is 

 effected simply by leaving the weeds taken off the land in lines 

 along contours at suitable distances. Soil wash is arrested by the 

 weeds, and in course of time solid banks are formed, attaining in 

 places a height of five feet. Similarly in the Kikuyu country weeds 

 and crop residues are placed along contour lines. On flatter 

 country mound cultivation, of which an advanced example is the 

 mounding for yams, a common practice in many parts of East 

 and West Africa, serves the same purpose. The extension of such 

 practices to areas where they are not indigenous is one of the ways 

 in which erosion may be prevented. 



IMPROVEMENT OF NATIVE CULTIVATION 



The serious situations which have arisen through native agri- 

 cultural practice, outlined above and in the paragraphs devoted 

 to soil erosion and deterioration in Chapter V, are recognized by 

 agricultural authorities throughout the continent. Much work is 

 in progress on the prevention of further damage to the soil and 

 the improvement of native methods generally, but most of such 

 work is of recent origin and at present there is little published 



