CROP-PLANTS 343 



much to improve the yield of maize in the case both of settler and 

 native production. 



Rice [Oryza sativa and 0. glaberrima) is a crop of increasing impor- 

 tance, particularly in West Africa. In Sierra Leone, for example, 

 rice forms a staple food of practically all the population, and 

 although large quantities are produced on the upland rice farms, 

 an import of 10,000 tons per year was necessary until recently. The 

 problem has been to increase production without affecting ad- 

 versely the fertility of the upland rice farms, and the solution 

 appeared unattainable until about ten years ago, when swamp- 

 growing rice was developed in the Scarcies area. By 1935 some 

 30,000 acres of mangrove swamp had been converted into rice- 

 fields and a small export had actually been started. Varieties have 

 been introduced from India, Ceylon, British Guiana, and Indo- 

 China, and strains have been selected suitable for the peculiar 

 local conditions, as for example, 'deep-water rice', and one form 

 has been acclimatized which will grow in as great a depth as 

 eight feet. The type known as G.E.B. 24, an introduction from 

 Madras, tested and multiplied at the experimental station at 

 Rokupr, has proved most successful. Through examination of the 

 product brought to the government rice mill, it is possible to ascer- 

 tain the areas where diseases occur, and where methods of cultiva- 

 tion require improvement. 



In Nigeria the pressure of population in the neighbourhood of 

 the large native towns of the Southern Provinces has compelled 

 the agricultural department to consider the development of new 

 areas where food crops can be grown. Accordingly an investiga- 

 tion into the possibilities of developing rice-fields in the mangrove 

 swamps in the neighbourhood of the Niger Delta has been made 

 recently with encouraging results. Although such cultivation is 

 rendered difficult by the proximity of salt water, so that only 

 restricted areas of mangrove swamp can be used, it has the great 

 advantage that the soil fertility is continually being replenished 

 by the rise and fall of the water due to tidal action, so that its 

 productivity is apparently inexhaustible. 



In Tanganyika the department of agriculture has investigated 

 the rice-growing area of the Pare district, where the native methods 

 of cultivation have been found to be wasteful. Already a good in- 



