PLANT INDUSTRY 38 1 



material referring to the results, except scattered references in 

 annual reports of agricultural departments. 



Perhaps the most obvious solution to the problem of erosion is to 

 transfer populations from mountainous or sloping land to the 

 plains and river valleys at lower levels, and this has been done 

 with success in parts of the continent where pressure of population 

 does not yet exist. This, however, is seldom practicable on a large 

 scale; accordingly it is also necessary to find means of extending 

 the period of fertihty of cultivated land. The ideal, of course, is to 

 render soil permanently fertile by instituting methods of manuring 

 to counterbalance the strain on fertility which results from con- 

 tinuous cropping. But this ideal is not often to be achieved with- 

 out a series of intermediate stages by which the period of cropping 

 in systems of shifting cultivation is increased, and the period of 

 reversion to natural vegetation is reduced. This, as the central 

 problem of agriculturalists in many native areas throughout the 

 continent, deserves discussion in some detail. 



Nigeria contains the densest agricultural population in Africa, 

 especially in the areas surrounding the large cities, and since there 

 is no European community, agricultural studies have been directed 

 entirely to the problems of native cultivation. Mr. O. T. Faulkner, 

 until recently Director of Agriculture, in collaboration with Mr. 

 J. R. Mackie, who has now succeeded him, has written a valuable 

 book (1933) describing the agricultural situation in West Africa 

 with particular reference to Nigeria. The following account is 

 based on that work, together with information provided more 

 recently by members of the department. For agricultural purposes 

 the country can be divided into the Northern Provinces, with an 

 arid climate and one rainy season, where cattle are farmed in 

 large numbers, and the Southern, with a damper climate, two 

 rainy seasons and very little stock on account of widespread tsetse 

 fly. The south, however, must itself be divided into eastern and 

 western regions, owing to the differences in soil. The east is cov- 

 ered with acid soils which are generally similar for agricultural 

 purposes, although, on geological grounds, they are divided into 

 Benin sands and alluvium. In the west, however, the soils are 

 much richer and less acid. Hence, though every crop of the east 

 will grow in the west, the converse is not true. Cocoa and cotton 



