Properties and indigenous knowledge of soil materials used for consumption, healing and cosmetics in KwaZulu-Natal, South Africa

Ethnopedological studies focus on agricultural soils resulting in undervaluation of non-agricultural soil materials during land classification. In this study, ethnographic and ethnopedologic methods were used to obtain local knowledge and gain in-depth understanding of non-agricultural soils, their mineralogical and elemental composition relating to application in geophagy, healing and cosmetic purposes in two villages in KwaZulu-Natal, South Africa. In each village a questionnaire was administered to fifty randomly selected individuals from which ten knowledgeable volunteers (including eight geophagists from two villages) provided details on the selection criteria, the desired properties and why the soils performed the claimed role. Users based their selection on macromorphological features (e.g. colour, texture and location within the soil) and indigenous knowledge. Geophagic materials were mainly sourced from C horizons. They were mostly fine-grained with mica, kaolinite and quartz, and elements such as copper (Cu), zinc (Zn), cobalt (Co) and lead (Pb). Natural pigments, such as iron oxides in highly weathered soils, were recognised as sunscreen materials. Although the mechanisms were not understood by users, laboratory analyses showed that the mineralogical and chemical properties of the soil materials played a crucial role. The sunscreen and healing capabilities of these soils were related to high contents of titanium (TiO2) and iron (Fe2O3) and the presence of kaolinite. Further appraisal of these soil materials is necessary for their conservation and inclusion in land classification.

Automated summary

This study used ethnographic and ethnopedological methods to explore the properties and applications of non-agricultural soils in two villages in KwaZulu-Natal, South Africa. The research found that these soils are commonly used for geophagy, healing, and cosmetic purposes. Users selected soils based on their macroscopic features and indigenous knowledge, and laboratory analysis showed that the mineralogical and chemical properties of the soils played a crucial role in their functionality.