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University of KwaZulu-Natal (2018)

Application of soil indigenous knowledge in rural communities of eastern South Africa.

Buthelezi, Nkosinomusa Nomfundo

Titre : Application of soil indigenous knowledge in rural communities of eastern South Africa.

Auteur : Buthelezi, Nkosinomusa Nomfundo.

Université de soutenance : University of KwaZulu-Natal

Grade : Doctor of Philosophy in Soil Science 2018

Résumé
This study investigated ethnopedological knowledge related to classification, fertility and non-agricultural uses of soil in four villages in KwaZulu-Natal and the Eastern Cape, South Africa. Ethnographic methods elicited general soil indigenous knowledge. Ethnopedologic techniques gathered understanding of soil taxonomy, mapping and fertility, and selection and use of healing, cosmetic and geophagic soils. Local assessments of soil fertility and mapping were compared to scientific approaches. Soil samples were analysed for physicochemical properties. Soils used for non-agricultural purposes were analysed by X-ray diffraction and X-ray fluorescence spectrometry. Local classifications were based on observable soil morphological properties. Soil maps produced by farmers in areas with distinct geomorphic units closely correlated with scientific maps ; on a floodplain the correlation was poor. Farmers assessed soil fertility using both crop and soil variables. There was poor correlation between farmers’ fertility classes and laboratory data. Farmers understood soil-crop associations which formed the basis for their soil suitability assessment and have developed specific soil use and management practices. Two soil types were identified for non-agricultural uses. Ukhethe, used for agriculture, was also used for geophagy ; ibomvu for sun protection, healing and cosmetics. Geophagic soils were mainly saprolite from Leptosols. They were mostly fine-grained, had bright Munsell hues, contained mica, kaolinite, quartz and iron oxides, and elements such as Cu, Zn, Co and Pb. Ibomvu occurred in Ferralsols and was red to dark-red. Despite low sun protection factors, critical wavelengths >370 nm, the presence of TiO2 and high Fe2O3 explained its sun protection ability. The soil was fine grained, had low pH and exchangeable bases, and contained kaolinite that possibly explained its healing role. These communities applied their pedological knowledge to soil use and management. There were diverse non-agricultural uses and possible land use conflicts where a soil has more than one use. Farmers classified soils at levels that could be incorporated as higher categories in the current South African system. Farmer fertility assessment could benefit from laboratory data. Soil suitability classification systems should be used to assess both agricultural and non- agricultural uses. Valuing all local uses of soil will ensure fair and relevant land use planning.

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