SOIL SCIENCE 13^ 



would certainly be a valuable addition to the published Atlas of 

 the Gold Coast. 



Sierra Leone was the first British colony to have a soil survey 

 completed in outline; it was clone by Martin and Doyne (1932) 

 and was based on the analysis of 1,500 samples, each taken to a 

 depth of four feet. Problems here are relatively simple since con- 

 ditions are similar over most of the territory. Laterite or lateritic 

 soilsi predominate, with a resultant lack of lime and prepon- 

 derance of acidity; phosphorus and potassium contents are low, 

 and humus is high before cultivation, but very low afterwards. 

 Surveys such as this provide a useful basis for further study, but 

 the authors would be the first to point out that additional informa- 

 tion is necessary in order to determine the areas suitable for dif- 

 ferent crops. Studies of the relation between the vegetation dis- 

 tribution and soil types are required and then the agricultural 

 significance of soil type and soil change should be worked out, but 

 the agricultural department no longer includes a chemist who 

 could undertake such work. 



FRENCH 



In French territory studies of this and of other subjects have 

 been carried further in Indo-China and Madagascar than in 

 Africa. The laboratory of agricultural chemistry at Tananarive in 

 Madagascar for example, has published during the past few years 

 numerous soil studies, some of which are important in relation to 

 work on the African continent. In French West Africa there are 

 now agricultural chemists at the chemical laboratory of the 

 Office du Niger at Segou in the Sudan, at the experimental 

 station for groundnuts at M'Bambey in Senegal and in the Ivory 

 Coast. Wide-scale soil survey has not been attempted, but impor- 

 tant researches have been carried out, in connection with the cul- 

 tivation of the banana in French Guinea, and of the oil palm in 

 the Ivory Coast, and others in the Sudan in connection with the 

 Niger irrigation works. The laboratory attached to the botanic 



* The terms laterite and lateritic have been used somewhat loosely by some authors. 

 Martin and Doyne (1932) laid down precise definitions based on the silica-alumina 

 ratios : soils with a ratio less than i -33 are laterite, from i •33-2-0 lateritic, and above 

 2-0 non-lateritic. That definition has been used in their soil survey of Sierra Leone, 

 but most workers now incline to the view that though the ratios may be used to 

 define the terms, they have little relation to any soil property. 



