No abstract available / Dissertation (MSc)--University of Pretoria, 2013. / am2013 / Genetics / unrestricted

Long-term food security and environmental quality are closely linked to maintaining soil quality. Therefore, the assessment of the effect of agricultural management practices on soil chemical, physical and biological parameters provide fundamental information about sustainability. An agricultural management practice which has received much attention in the last decade is tillage. The loss of topsoil due to erosion and a reduction of soil organic matter under conventional tillage practices, together with escalating fuel prices, have lead to the increased implementation of conservation tillage practices. However, the response of soil to a reduction in tillage is dependent on the inherent soil properties, environmental conditions, crop type and the land management practices. The successful implementation of conservation tillage practices is thus site specific. Furthermore, the effect of fertilizer application on soil quality is affected by tillage regime and therefore has important implications for recommendations of fertilizer application rates. The objectives of this study were to investigate the effect of tillage regime at three rates of nitrogen fertilization on soil microbial activity and selected soil physical properties in the Loskop area of KwaZulu-Natal, South Africa. Based on the outcomes of these investigations, recommendations regarding sustainable tillage practice and nitrogen fertilizer application rate are made. A field trial was initiated in 2003 on Gourton Farm in the Loskop area of KwaZulu-Natal on an area that was previously under annual conventional tillage and is currently planted to dry-land maize. The trial was arranged as a split plot experimental design with tillage regime (whole plots) replicated three times, and fertilizer type and application rate forming randomized subplots within the whole plots. The trial was on a clay loam soil type (Hutton soil form). The effects of annual conventional tillage (CT1) and no-till (NT) at three rates of nitrogen (N) fertilizer (as limestone ammonium nitrate (LAN)) applied at rates of 0 kg N ha-1 annum-1 (0N), 100 kg N ha-1 annum-1 (100N) and 200 kg N ha-1 annum-1 (200N) were evaluated for their effects on soil organic carbon (SOC), microbial activity, bulk density (ñb), water retention characteristics, saturated hydraulic conductivity (Ks), micro-aggregate stability and soil penetration resistance. Undisturbed soil cores were taken from three inter-rows in triplicate from each sub-plot for the A horizon (0 to 20 cm) and from three inter-rows in duplicate for the B horizon (20 to 40 cm). These undisturbed soil cores were used to determine the ñb, water retention characteristics and Ks. Bulk soil samples were collected from three inter-rows in triplicate from each sub-plot for the A (0 to 20 cm) and B (20 to 40 cm) horizons. The bulk samples from each horizon in each sub-plot were thoroughly mixed and halved. One half was used to determine microbial activity as measured by the hydrolytic and cellulolytic activity and the other half was used to determine SOC content, particle size distribution and aggregate stability. Penetration resistance was taken in duplicate in three rows in each sub-plot at 1 cm increments to a depth of 50 cm or until an instrument limiting penetration resistance of 5000 kPa was reached. Tillage regime and N application rate considerably affected soil microbial and physical properties in the A horizon (0 to 20 cm). The SOC, hydrolytic activity and ñb are significantly greater (P 0.05) effect on the soil microbial activity and physical properties except for Ks, where the Ks is significantly (P 0.05) in the B horizon on the measured soil microbial activity and physical properties except for the penetration resistance. Increasing levels of fertilizer resulted in increased penetration resistance throughout the soil profile under NT. Under CT1, this same trend is evident from below the plough layer. These results indicate that the microbial activity, as measured by hydrolytic and cellulolytic activity, is improved under NT compared to CT1. Furthermore, the soil under NT retains more plant available water (PAW) and although the ñb and penetration resistance are greater there was no obvious adverse effect on maize growth. In addition, a high rate of LAN fertilizer adversely affected soil microbial and physical properties, especially under NT. Therefore, it is proposed that NT is the preferred tillage practice in providing long-term sustainability and soil health without causing negative soil structural properties for crop productivity in the short-term. In addition, it is recommended that although increased levels of nitrogen fertilizer results in higher yielding maize plants it is unsustainable to apply high applications of LAN due to the negative effect on the soil microbial and physical properties and thus there is a need to re-evaluate the sustainability of using high rates of LAN to increase crop yields, especially under NT systems. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.

As part of a vegetation survey program for the newly acquired farms incorporated into the Loskop Dam Nature Reserve, the vegetation of the Hondekraal Section was investigated. The study provides an ecological basis for establishing an efficient wildlife management plan for the Reserve. From a TWINSPAN classification, refined by Braun-Blanquet procedures, 12 plant communities, which can be grouped into eight major plant communities, were identified. A classification and description of the major plant communities are presented as well as a management plan. Descriptions of the plant communities include characteristic species as well as prominent and less conspicuous species of the tree, shrub, herb and grass strata. This study proves that the extended land incorporated into the Reserve contributes to the biological diversity of the Reserve. / Environmental Sciences / M. Tech. (Nature Conservation)

A population survey was conducted on Galago moholi along the road system at Loskop Dam Nature Reserve, Mpumalanga province, South Africa. The data were analyzed using the maximum perpendicular distance, mean perpendicular distance, and maximum reliable perpendicular distance methods. Vegetation sample plots were constructed at the location of each individual sighted in order to analyze the species’ habitat use. The results indicate that the species density of G. moholi is significantly lower at Loskop Dam Nature Reserve than previously reported at other sites within South Africa. G. moholi was found to prefer areas with high concentrations of Dichrostachys sp., Combretum sp., or Acacia sp. One individual was observed consuming vegetative matter, which may indicate that the population within the reserve is utilizing available resources in a different way than populations in other parts of southern Africa. / Department of Anthropology

As part of a vegetation survey program for the newly acquired farms incorporated into the Loskop Dam Nature Reserve, the vegetation of the Hondekraal Section was investigated. The study provides an ecological basis for establishing an efficient wildlife management plan for the Reserve. From a TWINSPAN classification, refined by Braun-Blanquet procedures, 12 plant communities, which can be grouped into eight major plant communities, were identified. A classification and description of the major plant communities are presented as well as a management plan. Descriptions of the plant communities include characteristic species as well as prominent and less conspicuous species of the tree, shrub, herb and grass strata. This study proves that the extended land incorporated into the Reserve contributes to the biological diversity of the Reserve. / Environmental Sciences / M. Tech. (Nature Conservation)

M.Sc. / Please refer to full text to view abstract

The principal reason for the construction of Loskop Dam was to provide irrigation water to wheat farmers settling in the Olifants River valley in the 1920s. Agriculture has since developed in the area and today, the Loskop Irrigation Board supplies water to > 700 properties with an area of 25 600 ha farming cotton, wheat, citrus and grapes near the town of Groblersdal. Serious concerns were raised about deteriorating water quality when the crocodile population began to decline and the frequency of large fish kills increased from 2006. Crocodile (Crocodylus niloticus) and Mozambique tilapia (Oreochromis mossambicus) mortalities were linked to pansteatitis which is characterised by obesity and lipid peroxidation. Known impacts on water quality include eutrophication and acid mine drainage from coal mining with associated increases of soluble metals. The aims of this study were to: i) determine whether pansteatitis could be linked to any specific parameters in the water chemistry and limnology of Loskop Dam; ii) measure concentrations of aluminium, copper, iron, manganese, selenium and zinc in various tissues of O. mossambicus to determine whether bio-accumulation was occurring and could be related to pansteatitis; iii) assess the metazoan parasite communities of O. mossambicus to determine whether they are effective indicators of ecosystem health in Loskop Dam. Four established sampling sites were used at Loskop Dam and a reference site was located at neighbouring Kranspoort Dam. Surface water quality samples were collected monthly between July and December 2010 from each site and analysed for 27 constituents including nutrients, major ions, total metals, pH and dissolved oxygen using standard methods. Orthophosphate and total inorganic nitrogen results frequently categorised Loskop Dam as eutrophic and the transitional zone of the dam was characterised by very alkaline conditions resulting from algal blooms (median pH 9.67) which increase the solubility of metals like Al. A combination of active and passive biomonitoring techniques were used for fish collection. Fish gills, brain, muscle, liver and bone were analysed for Al, Fe, Mn, Zn, Cu and Se concentrations. The most striking result was an unanticipated significant deficiency in liver Cu concentrations of fish from Loskop Dam (mean 3.4 mg kg-1) compared to fish from Kranspoort Dam (mean 62 mg kg-1). Both endo- and ectoparasites were identified and enumerated on the fish and infection rates were calculated as mean intensity (I), mean abundance (A) and prevalence (P). Fish from Loskop Dam had extremely low infection rates and two fish had no parasites whatsoever. The ratio between monoxenous and heteroxenous parasites was calculated and was very high in fish from Loskop Dam compared to fish in Kranspoort Dam and Tompi Seleka, indicating a degraded aquatic ecosystem. While no single factor was outstanding as a possible cause of pansteatitis in this study, these findings provide a good foundation from which to formulate further research questions. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Paraclinical Sciences / unrestricted

Magister Scientiae - MSc (Environ & Water Science) / The upper Olifants River catchment, situated in Mpumalanga Province, South Africa, is one of the main sources of water for this region. This region face challenges to guarantee future water security due to intensive land use activities e.g. mining, energy production, and agriculture activities. South Africa is the sixth largest producers of coal in the world and the Witbank (eMalahleni) coal fields, situated in the catchment, represents the largest conterminous area of active coal mining in South Africa. The second largest irrigation scheme (Loskop dam Irrigation Board) is also found below the Loskop Dam in the upper Olifants River catchment. The irrigation scheme of + - 480 km of irrigation channels provides water for a R1 Billion export industry of citric fruits to the European Union. Furthermore, the Olifants River in Mpumalanga is also a trans-boundary river that initially flows northwards before curving in an easterly direction through the Kruger National Park and into Mozambique where it joins the Limpopo River before discharging into the Indian Ocean. Although the Olifants River is one of the main river systems in South Africa, it has been described as one of the most polluted rivers in southern Africa, with Loskop Dam acting as a repository for pollutants from the upper catchment of the Olifants River system. Because Loskop Dam is of strategic important for the whole region the aim of the study was to show the implications of poor water quality on the local communities down stream of Loskop Dam that depend on water usage for their livelihood. (1) Developing a modified pollution index for the Loskop Dam, Mpumalanga Province using bioindicator algae species in relationship with water column physico-chemical parameters and national water guidelines as indication of pollution. (2) Analysing the threat of cyanobacteria, microsystin contaminations to crops irrigating by water from the Loskop Dam irrigation canals. (3) Discussing the social economic implication of water pollution on the Loskop Irrigation scheme and its stakeholders.

The vegetation of the Nooitgedacht section of the Loskop Dam Nature Reserve resembles Bankenveld vegetation and differs from the other areas of the reserve. This study was undertaken to identify, classify, and describe the plant communities present on this section, and to determine their veld condition. The Braun-Blanquet approach was followed to classify the different plant communities. A total number of 170 sample plots (100m2) were placed in all homogeneous vegetation units in a randomly stratified basis. The Ecological Index Method (EIM) was used to determine the veld condition. Data were collected using the steppoint method and incorporated into the GRAZE model from where the veld condition was calculated. A minimum of 400 step points were surveyed in each community with more points in the larger communities. Plant community data was analysed using the JUICE software program. A total of 11 plant communities were identified. The overall veld condition score indicates the vegetation to be in a good condition, resulting in a high grazing capacity. / Environmental Sciences / M. Sc. (Nature Conservation)

The vegetation of the Nooitgedacht section of the Loskop Dam Nature Reserve resembles Bankenveld vegetation and differs from the other areas of the reserve. This study was undertaken to identify, classify, and describe the plant communities present on this section, and to determine their veld condition. The Braun-Blanquet approach was followed to classify the different plant communities. A total number of 170 sample plots (100m2) were placed in all homogeneous vegetation units in a randomly stratified basis. The Ecological Index Method (EIM) was used to determine the veld condition. Data were collected using the steppoint method and incorporated into the GRAZE model from where the veld condition was calculated. A minimum of 400 step points were surveyed in each community with more points in the larger communities. Plant community data was analysed using the JUICE software program. A total of 11 plant communities were identified. The overall veld condition score indicates the vegetation to be in a good condition, resulting in a high grazing capacity. / Environmental Sciences / M. Sc. (Nature Conservation)