Soil salinity (due to ingress of excess amounts of dissolved salts in soil pores) and soil sodicity (due to excess amounts of sodium ions attached to the clay surface) are significant forms of land degradation in many parts of the world in particular in arid and semi arid regions. In Australia, soil salinity has long been identified as the major form of land degradation and the greatest environmental threat. Saline soils cover almost 6% of Australia’s land mass and impose severe threats on agricultural productivity and built infrastructure with an estimated annual loss of $250 million. In recent years, ‘soil sodicity’ is recognised as a far more significant form of land degradation and a severe environmental problem both in terms of affected land area and impact on the environment than is salinity as a problem in Australia. One third of Australian land mass is occupied by sodic soils costing an estimated $2 billion each year in lost production alone, with further significant impacts on the economy due to extensive damage to infrastructure facilities and the environment. [...] / Doctor of Philosophy

Thesis (Ph. D.)--University of Adelaide, Dept. of Soil Science, 1996. / Copies of author's previously published articles in pocket inside back cover. Includes bibliographical references (leaves 147-160).

Thesis (M. Ag. Sc.)--University of Adelaide, Dept. of Soil Science, 1997. / Includes bibliographical references (leaves 159-177).

Thesis (M.Ag.Sc.) -- Dept. of Soil and Water, Waite Agricultural Research Institute, University of Adelaide, 2002? / Bibliography: leaves 105-129.

Made available in DSpace on 2014-06-11T19:27:22Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-16Bitstream added on 2014-06-13T18:31:27Z : No. of bitstreams: 1 badin_f_me_jabo.pdf: 588683 bytes, checksum: 95acfa363bf6d9a1c4fd8c48c39fdd26 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / As indústrias sucroenergéticas têm como preocupação o controle de contaminantes da fermentação, responsáveis por afetar a viabilidade da levedura, provocando diversos transtornos no processo, comprometendo a eficiência fermentativa e o rendimento industrial. Dentre as alternativas para o controle das contaminações, destacam-se o uso de antimicrobianos sintéticos. Sua utilização continua pode favorecer o desenvolvimento de cepas resistentes, contribuindo para o incremento do custo de produção, além da possibilidade de incorporação de resíduos no produto final. Objetivou-se avaliar o efeito do biocida convencional (monensina sódica) e biocidas naturais preparados à base de própolis (Extrato Hidroalcoólico de Própolis - EHP e Extrato Oleoso de Própolis- EOP) sobre a fisiologia das leveduras, o controle dos contaminantes do processo fermentativo e composição do destilado. O delineamento experimental utilizado foi o Inteiramente Casualizado com parcelas subdivididas, com 4 repetições. Os Tratamentos Principais foram: Testemunha, EOP, EHP e monensina sódica (Kamoran WP). Os Tratamentos Secundários constituíram-se nos 10 ciclos fermentativos. Avaliaram-se as características químico-tecnológicas do caldo, mosto e vinho, parâmetros microbiológicos das leveduras e composição do destilado obtido. Os resultados obtidos demonstraram que os biocidas avaliados apresentaram efeito similar, sendo efetivos no controle dos contaminantes da fermentação, não afetando negativamente suas características fisiológicas. Não afetaram a composição a composição do destilado final obtido / The control of fermentation contaminants is one of the sugar mills concerns. The fermentation contaminants are responsible to affect the yeast viability, generating several overturns to the process, compromising the fermentative efficiency as well the industrial yield. Among the alternatives to control contamination, the use of synthetic antimicrobials can be highlighted. Its progressed use may favor the development of resistant strains, contributing in production cost improving, besides the possibility of residues incorporation into the final product. This work aimed evaluate the effect of conventional biocides (sodic monensin) and natural ones based on propolis (Propolis Hydroalcoholic Extract – EHP and Propolis Oily Extract – EOP) under the yeasts physiology, the fermentative process contaminants control, and the distilled composition. The experimental design used was the split-plot with four replications. The main treatments were: Control, EOH, EHP, and sodic monensin (Kamoran WP). The secondary treatments were the 10 fermentative cycles. The evaluated characteristics were: juice, must, and wine chemical-technical characteristics, yeasts microbiologic parameters, and the distillated obtained composition. The results obtained showed that the evaluated biocides presented similar effect, being effectives to control the fermentation contaminants, not affecting negatively its physiologic characteristics. They did not affect the composition of the distilled obtained

Understanding relationships between large herbivores and plant species diversity in dynamic riparian zones, and more specifically sodic zones, is critical to biodiversity conservation. Sodic patches form an integral part of savanna ecosystems because of the ecosystem services and functions they provide, i.e. accumulation of nutrients, provision of open spaces for predator vigilance and formation of wet season wallowing points. Furthermore, these key resource areas sustain body condition for dry season survival and support reproduction through nutritional benefits, making them „nutrient hotspots.‟ The Nkuhlu research exclosures in the Kruger National Park (KNP) provide a unique opportunity to investigate spatial and temporal heterogeneity patterns within riparian zones, and how these patterns are affected by fire and herbivory. A monitoring project was initiated to answer questions pertaining to the dynamics of the herbaceous layer and was aimed at determining (a) whether there exists meaningful variance in herbaceous plant species richness and diversity across different treatments of fire and herbivory in the ecologically sensitive sodic zone, (b) if temporal shifts in plant species composition and diversity occurs, (c) whether an increase in herbaceous biomass, an artifact of herbivory and fire exclusion, suppresses herbaceous plant species diversity and richness, and (d) whether there exists a significant relationship between herbaceous biomass and species richness/diversity. The Nkuhlu exclosures consist of three herbivory treatments, each divided into a fire and no-fire treatment, hence six treatment combinations overall. Herbivory treatments consisted of, (1) a partially fenced area designed to specifically exclude elephants (giraffes are also excluded due to body size), (2) an open, unfenced area and (3) a fully fenced area, designed to exclude all herbivores larger than a hare. Herbaceous vegetation was sampled in two 1 m2 circular sub-plots in the eastern and western corners of each of the 82 fixed plots. Biomass of each plot was estimated with a Disc Pasture Meter (DPM) by sampling ten points diagonally within each plot. DPM-readings were converted to kg/ha according to latest conversions for the Lowveld Savanna. Species richness and biomass showed significant variance across treatments for the 2010 dataset, whereas no significant variation in herbaceous species diversity was perceived. Combined treatment of fire absence and herbivore presence contributed to higher forb species richness in the sodic zone. Biomass was significantly higher in fully fenced areas where herbivores were excluded, opposed to the open and partially fenced areas. Although no significant variation was recorded for diversity across treatments, lowest diversity was recorded in the absence of all herbivores, especially in combination with fire treatment. After nine years of herbivory exclusion, diversity of herbaceous species varied significantly. Herbaceous species composition changed over time in areas exposed to herbivory, while composition of fully fenced treatments did not reveal change. A hump-shaped relationship exists between herbaceous species richness/diversity and field biomass, at least for areas with biomass levels not exceeding 2500 kg/ha. Herbivores are therefore considered essential in sustaining herbaceous plant species richness and system heterogeneity in the sodic zone, since herbaceous species richness/diversity was higher in herbivore presence and herbaceous species composition changed over time in areas exposed to herbivory. Although statistically non-significant, fire seems to suppress species richness. Conservation implications: This study could be used as framework to advance and develop sciencebased management strategies for, at least, the sodic zones of the KNP. Research in these exclosures contributes to our understanding of these landscapes and benefit ecosystem conservation planning. It also provides valuable long-term data for key ecological processes. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Understanding relationships between large herbivores and plant species diversity in dynamic riparian zones, and more specifically sodic zones, is critical to biodiversity conservation. Sodic patches form an integral part of savanna ecosystems because of the ecosystem services and functions they provide, i.e. accumulation of nutrients, provision of open spaces for predator vigilance and formation of wet season wallowing points. Furthermore, these key resource areas sustain body condition for dry season survival and support reproduction through nutritional benefits, making them „nutrient hotspots.‟ The Nkuhlu research exclosures in the Kruger National Park (KNP) provide a unique opportunity to investigate spatial and temporal heterogeneity patterns within riparian zones, and how these patterns are affected by fire and herbivory. A monitoring project was initiated to answer questions pertaining to the dynamics of the herbaceous layer and was aimed at determining (a) whether there exists meaningful variance in herbaceous plant species richness and diversity across different treatments of fire and herbivory in the ecologically sensitive sodic zone, (b) if temporal shifts in plant species composition and diversity occurs, (c) whether an increase in herbaceous biomass, an artifact of herbivory and fire exclusion, suppresses herbaceous plant species diversity and richness, and (d) whether there exists a significant relationship between herbaceous biomass and species richness/diversity. The Nkuhlu exclosures consist of three herbivory treatments, each divided into a fire and no-fire treatment, hence six treatment combinations overall. Herbivory treatments consisted of, (1) a partially fenced area designed to specifically exclude elephants (giraffes are also excluded due to body size), (2) an open, unfenced area and (3) a fully fenced area, designed to exclude all herbivores larger than a hare. Herbaceous vegetation was sampled in two 1 m2 circular sub-plots in the eastern and western corners of each of the 82 fixed plots. Biomass of each plot was estimated with a Disc Pasture Meter (DPM) by sampling ten points diagonally within each plot. DPM-readings were converted to kg/ha according to latest conversions for the Lowveld Savanna. Species richness and biomass showed significant variance across treatments for the 2010 dataset, whereas no significant variation in herbaceous species diversity was perceived. Combined treatment of fire absence and herbivore presence contributed to higher forb species richness in the sodic zone. Biomass was significantly higher in fully fenced areas where herbivores were excluded, opposed to the open and partially fenced areas. Although no significant variation was recorded for diversity across treatments, lowest diversity was recorded in the absence of all herbivores, especially in combination with fire treatment. After nine years of herbivory exclusion, diversity of herbaceous species varied significantly. Herbaceous species composition changed over time in areas exposed to herbivory, while composition of fully fenced treatments did not reveal change. A hump-shaped relationship exists between herbaceous species richness/diversity and field biomass, at least for areas with biomass levels not exceeding 2500 kg/ha. Herbivores are therefore considered essential in sustaining herbaceous plant species richness and system heterogeneity in the sodic zone, since herbaceous species richness/diversity was higher in herbivore presence and herbaceous species composition changed over time in areas exposed to herbivory. Although statistically non-significant, fire seems to suppress species richness. Conservation implications: This study could be used as framework to advance and develop sciencebased management strategies for, at least, the sodic zones of the KNP. Research in these exclosures contributes to our understanding of these landscapes and benefit ecosystem conservation planning. It also provides valuable long-term data for key ecological processes. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2014

Includes bibliographical references (leaves 78-86) In the Herrmanns sub-catchment in the Mt. Lofty Ranges (near Mt. Torrens) soil sodicity was the dominant factor in causing clay to disperse in the eroded area along the foot slopes, wheras in non-eroded areas of the mid-slopes and on the stream banks, the dispersive power of sodicity was attenuated by the flocculative power of other soil properties.

Bibliography: leaves 105-129.

Copies of author's previously published articles in pocket inside back cover. Bibliography: leaves 147-160. This thesis outlines the factors affecting soil strength and structural stability and their interrelationship in salt-affected soils. The objectives of this study are to investigate the influence of clay particles on soil densification and mellowing, the mellowing of compacted soils and soil aggregates as influenced by solution composition, the disaggregation of soils subjected to different sodicities and salinities and its relationship to soil strength and dispersible clay and the effect of organic matter and clay type on aggregation of salt-affected soils.