I2 7 



periodical enrichment of these districts with fertilizing- 

 elements, under somewhat special conditions : direct enrich- 

 ment with nitrogen from the air (nitrogen-fixing bacteria) ; 

 enrichment with nitrogen, phosphoric acid, potash, lime and 

 humus, by means of various complex substances, carried down 

 by the river waters (manure from the flocks, drainage from the 

 villages, &c.). The secret of making this country of real value 

 lies in the close union of cattle-breeding with cultivation. 



DETERMINATION OF THE MANURIAL REQUIREMENTS CF 

 SOILS IN THE BELGIAN CONGO. 



By F. SMEYERS, 

 Director, Colonial Office, Brussels. 



[ABSTRACT.] 



The two following methods of investigation are used in, the 

 study of the soils of the Belgian Congo: 



(1) Mechanical and chemical analysis. 



(2) Physiological analysis by plants, either by means of pot 

 cultures or in field experiments. 



For mechanical and chemical analysis two laboratories have 

 been established in the Colony ; one of these was first situated 

 at Eala (Equator), but was transferred to Zambi (Lower 

 Congo) in 1913; the other was erected at Elisabethville 

 (Katanga) in 1912. 



The work of these two laboratories is devoted exclusively 

 to the study of soils. They both use the same methods of 

 analysis (Wohltmann Method), so that comparable results are 

 obtained. One hundred and twenty-seven analyses were made 

 in these two laboratories in 1913. A number of chemical 

 analyses of Congo soils were made also in Belgium in different 

 Government laboratories. 



This work is completed by physiological analyses of the soils 

 by means of plant cultures. The necessary appliances for this 

 study will be available before long in the Belgian Congo. In 

 the meantime Mr. Schreiber, General-Director of the Belgian 

 Agricultural Department, has conducted at the Hasselt experi- 

 mental station a series of physiological analyses on five samples 

 of soils taken at Zambi (Lower Congo), and four samples taken 

 at Ganda-Sundi (Mayumbe). The nine samples were sown 

 with maize and oats in pots. 



This experiment is now in progress, and is intended to 

 reveal, through the plant itself, the elements that should be 

 added to the soils to increase their productivity. The method 



