142 SCIENCE IN AFRICA 



protozoa in the soil has been stressed by workers in England, but 

 the group has not been studied in tropical conditions. 



One way in which such biological studies may give fruitful 

 results is in relation to the use of mulches and manures. In Uganda 

 for example, marked success has been achieved by using cut grass 

 as a mulch for coffee. This effectively prevents erosion and soil 

 deterioration, but the reason is not known. A comparative study 

 of the biological and chemical changes occurring when the mulch 

 is, and is not used, would be of value, and might be undertaken at 

 Amani in collaboration with the technical staff of the territories 

 interested. 



One particular group of animals, the termites or white ants, of 

 which many species are abundant in Africa, deserve special atten- 

 tion. The ground formxs are certainly agents in soil evolution since 

 they are continually occupied in bringing to the surface quantities 

 of subsoil, or partly weathered rock, in order to build their termi- 

 taria, but the effect on fertility is not yet known. Vageler (1933) 

 states that in tropical Africa termitaria directly enrich the soil, 

 and experience in Nyasaland at the Zomba Experimental Station 

 also seems to indicate that their effects are beneficial; but Dr. A. L. 

 du Toit (1934) writing on South Africa, suggests that termites do 

 immense harm by cutting up, consuming, or storing grasses and 

 other growth, and thereby prevent the formation of humus. Dr. 

 T. J. Naude (1934), in one of the few studies so far published on 

 termites in relation to agriculture, also stresses the effect of these 

 insects in pastoral areas in South Africa. He considers that drought 

 conditions favour termites, and that, in the recent succession of dry 

 years which South Africa has suffered, the denudation occasioned 

 by termites has had a considerable bearing on soil erosion and the 

 loss of storm water by increasing the run-off. 



In arid regions, where wood and green vegetation are scanty or 

 lacking, termites are still numerous and must have food. The 

 habit which many species have, of cultivating fungi in their nests, 

 may provide this to some extent, but it has been suggested also 

 that they can feed directly on humus, and thus may be in part 

 responsible for the poverty of so many soils. In many parts of 

 Africa there are huge extinct termitaria, which are used by natives 

 for cultivation. These insects are considered more fully in Chapter X. 



