No description available.

Thesis (M.S. - Watershed Management)--University of Arizona. / Includes bibliographical references.

Thesis (M.S.)--Humboldt State University, 2007. / Includes bibliographical references (leaves 100-103). Also available via Humboldt Digital Scholar.

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains viii, 122 p. : ill., maps. Includes abstract. Includes bibliographical references (p. 78-85).

Thesis (Ph.D.)--University of Adelaide, Dept. of Civil and Environmental Engineering, 1999? / Corrigenda pasted onto front end-paper. Bibliography: leaves 307-326.

Biochar production and application to soil can mitigate climate change and improve soil quality. This thesis investigated the influence of biochar preparation methods and application rates on the hydrological and erosional characteristics of biochars themselves and the soils to which they were applied. Biochar hydrophobicity was influenced by feedstock and decreased with increasing highest treatment temperature (HTT). Biochar did not influence soil wettability and the effect of HTT on biochar porosity was more important for soil water-holding capacity than its effect on hydrophobicity. HTT affected biochar yield, cation exchange-capacity and provision of fungal substrates. HTT also significantly influenced the effect of biochar on soil suction. Smaller feedstock particles produced biochars that were slightly more hydrophobic than those produced from larger particles. The effects of biochar application on the properties of sandy loam were influenced by biochar particle size, because larger particles had less effect on bulk density and had slower water uptake. A low biochar application rate (5 g kg-1) had no effect on the aggregate stability of a silt loam and did not affect the hydrological and erosional response of the soil under simulated rainfall. Application rates of 25 and 50 g kg-1 reduced aggregate stability, which led to surface sealing and overland flow generation occurring more readily. However, there was no more erosion of these soils than those with low or zero biochar content, and the crusts formed by seal drying were much weaker than those formed on soils with low or zero biochar. Biochar was preferentially eroded from the soils, regardless of the application rate used. HTT and particle size can have important implications both for the properties of biochar itself and for its effects on soil properties. However, biochar may only substantially influence soil hydrology and erosion when applied at sufficiently high rates.

This thesis concerns soil erosion and conservation in Zimbabwe. It is framed in the light of the contemporary heightened concern for the environment generally in Africa and the recent publication of the National Conservation Strategy for Zimbabwe (1987). Soil erosion is an archetypal interdisciplinary problem. This thesis complements and extends understanding of soil erosion and conservation in Zimbabwe via a methodological approach and a scale of analysis which have been under-represented in the literature to date. The research adopts a pluralist, regional political ecology approach (after Blaikie and Brookfield 1987) to soil erosion and conservation in Svosve communal area, combining political-economic understanding with case study analysis of changing social-environmental relationships. Plural problem definitions are constructed through interview and survey techniques, historical analysiso f archival sourcesa nd oral testimonies,a ssessmenot f contemporary policy and planning documents and via sequential air photograph analysis. The researchc hallengesa spectso f the colonial conservationislti terature to date for southernA frica andn ational level modelling of human-environmenrte lationshipsi n Zimbabwe. It presentsa quantitativea ssessmenotf the changei n symptomso f deterioration and in the nature and extent of soil erosion for the case study area. It operationalisesth e concepto f multiple problem definitions with implications for the contemporary model for conservation extension and for improving the role of local development institutions.

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published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy