336 SCIENCE IN AFRICA 



collected. For example, in Uganda, when the locust invasion came 

 in 1 93 1, it was possible for the agricultural department to recom- 

 mend the extensive planting of locust-proof crops such as ground- 

 nuts, cassava, and sweet potatoes. Owing to co-operation between 

 field officers of the administrative and agricultural departments 

 this campaign was so successful that no famine reserves had to be 

 drawn on throughout the locust invasion. 



Passing to cash crops, it would appear possible at first sight to 

 distinguish those grown by European settlers from those produced 

 by natives. But recently so many crops established at first by settler 

 planters have been adopted by native cultivators, that the distinc- 

 tion can no longer be made, except in so far as the investment of 

 capital enables the European or Asiatic settler to employ methods 

 which are not available to the native. 



In some cases these economic crop-plants have been introduced 

 from outside Africa within recent years; in other cases indigenous 

 plants have been improved, often as a result of interbreeding with 

 introduced strains of the same species. As examples of recent 

 introductions, cacao in West Africa, and tea and wheat in the 

 East, may be cited. 



In view of the risk from variations in market or in climatic con- 

 ditions, which is involved by dependence on a single crop, as 

 well as the creation of an unbalanced agriculture, it has been felt 

 desirable to establish alternative crops wherever possible. Develop- 

 ments in Uganda may be quoted as an example. This territory at 

 one time concentrated on the cultivation of cotton, of which 

 approximately 300,000 bales are produced annually by native 

 cultivators. In Uganda this crop is comparatively safe owing to 

 climatic conditions and the relative absence of pests. It was real- 

 ized, however, that a slump in cotton prices would be disastrous, 

 and also that soil erosion was becoming a serious menace in areas 

 where this crop was grown in excess of its legitimate acreage. 

 Efforts have therefore been made to stimulate native production 

 of coffee, and lately also of tobacco. Difficulties in marketing the 

 variable quality of native-grown coffee have been overcome by 

 recent coffee-grading ordinances, and the native production in 

 Uganda now includes 4,500 tons of coffee and 1,000,000 lb. of 

 tobacco in addition to the cotton. A similar policy of creating a 



