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Accueil du site → Master → Afrique du Sud → 2022 → Soil erodibility indices affecting the development of gully erosion in highly erodible soils of the Tsitsa Catchment in T35D and T35E, Eastern Cape, South Africa

University of Fort Hare (2022)

Soil erodibility indices affecting the development of gully erosion in highly erodible soils of the Tsitsa Catchment in T35D and T35E, Eastern Cape, South Africa

Kanuka, Gcobisa

Titre : Soil erodibility indices affecting the development of gully erosion in highly erodible soils of the Tsitsa Catchment in T35D and T35E, Eastern Cape, South Africa

Auteur : Kanuka, Gcobisa

Université de soutenance : University of Fort Hare

Grade : Master of Science in Agriculture 2022

Résumé partiel
This study evaluated soil inherent properties for the development of gullies and their erodibility potential using the holistic field and laboratory sample investigation approach. The potential of negative impact of sedimentation on dam and water infrastructure performance has raised the need to evaluate the factors promoting soil erosion leading to land degradation. The study aimed to assess the relationship among the selected properties of soil and variability among various soil groups. A case study design approach was adopted at the T35D and T35E areas of Tsitsa hydrologic Basin, Eastern Cape, South Africa. The task was accomplished through detailed random soil sampling in the field, soil chemical analysis and comparative analysis of soil variables. Based on the scope of the study soil laboratory analysis included the following : particle size distribution, soil textural analysis, physicochemical parameters analysis, macro-and-micronutrient analysis, and micro-porosity analysis. Further spatial and scenario analysis of soil erodibility was done using selected erodibility indices such as Sodium Adsorption Ratio (SAR), Exchangeable Sodium Percentage (ESP), Dispersivity Ratio (DR), Clay Dispersion Ratio (CDR), Clay Flocculation Index (CFI), Water-Stable Aggregate analysis (WSA), and Soil Erodibility factor analysis (KEF). The findings of the study showed that the catchment hosts sixteen distinct soil forms categorized into seven unique soil groups. The results further indicated that the Katspruit soil form of the gleyic soil group has the highest clay-size particles and a considerably high clay dispersion attribute among others soil forms. It was further deduced that gleyic soil type exhibited the highest soil pH (6.36), a considerably low Ca:Mg ratio (1.43), a substantially high sodium ion (0.50 mg/kg), the highest SAR (0.5), lowest WSA (0.018percent) and a substantially high KEF (0.018ab). Similarly, saprolite soils exhibited the nature of the lixisol with a virtually equal amount of clay (43.63percent) and fine sands (41.68percent), the lowest amount of Ca:Mg ratio (1.35), the highest acid saturation (50.59), the highest ESP (8.39), and a considerably high WSA (38.75). Other remarkable problematic soils identified in the study include the lithic soil and the duplex soil.

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Page publiée le 16 janvier 2023