Time filter

Source Type

Palmer B.J.,Oceanographic Research Institute | Van Der Elst R.,Oceanographic Research Institute | MacKay F.,Oceanographic Research Institute | Mather A.A.,EThekwini Municipality | And 5 more authors.
Journal of Coastal Research | Year: 2011

The KwaZulu-Natal (KZN) coast is a popular tourist zone and therefore one of the most important assets underpinning the economic activities of this South African Province. As with many coastal regions, the disproportionately large human settlement at the coast has led to increased pressure on the coastal zone. Development increases bio-physical changes, leading to an escalation in environmental risks affecting coastal populations, infrastructure and natural coastal environments. The events induced by a rapidly changing climate added to coastal zone development potentially introduce synergistic negative responses that might or might not be predictable. Therefore there is a need to develop methods that assess coastal vulnerability, and determine how best to managed this risk. This paper reports on the development of a technique that investigated the relative coastal vulnerability of the KZN coast to erosion and extreme weather events. A Coastal Vulnerability Index (CVI) was developed based on remotely sensed data whereby a set of physical coastal parameters, which serve as indicators of risk or vulnerability, were captured. The CVI scores were used to rank the coast, based on its relative degree of vulnerability into five classes ranging from very low to very high and highlights what proportion of coast falls within each class. Coastal vulnerability must inform management, thus this assessment attempts to address social, economic and ecological factors by identifying indicators and assessing them in relation to the finding of the CVI to determine what structures and features are within areas of very high CVI scores. The information presented provides input into a decision support tool that will facilitate the effective and user-friendly transfer of this important information.

Miles N.,South African Sugarcane Research Institute | Miles N.,University of KwaZulu - Natal | Manson A.D.,Environmental Affairs and Rural Development | Rhodes R.,South African Sugarcane Research Institute | And 3 more authors.
Communications in Soil Science and Plant Analysis | Year: 2014

Reports of sugarcane yield responses to silicon (Si), coupled with mounting evidence that elevated crop Si levels reduce both biotic and abiotic stresses, account for the interest in the Si nutrition of this crop. In terms of managing Si supplies to sugarcane in South Africa, uncertainties exist regarding, first, the reserves of plant-available Si in soils, and second, the reliability of soil-test methods for predicting Si availability. In this study, extractable Si was measured in 112 soils collected from sugarcane-producing fields in South Africa. Soils were selected on the basis of dominant soil types and included Inceptisols, Alfisols, Mollisols, Vertisols, Oxisols, Entisols, and Ultisols, varying widely in chemical properties, texture, and extent of weathering. Extractants employed were 0.01 M calcium chloride (CaCl2) and 0.02 N sulfuric acid (H2SO4). Silicon extracted with 0.02 N H2SO4 ranged from 2 to 293 mg kg−1, whereas with 0.01 M CaCl2 the range was 5 to 123 mg kg−1. With both extractants, extractable Si decreased significantly with decreasing pH, exchangeable calcium (Ca), and total cations. In soils with potassium chloride (KCl)–extractable Al+H levels of greater than 0.5 cmolcL−1, extractable Si levels were consistently low, suggesting that soluble Al is implicated in reducing plant-available Si levels. Extractable Si levels were not related to the Bache and Williams P-sorption indices of soils. In the second part of the investigation, sugarcane leaf Si concentrations from 28 sites were related to soil extractable Si levels. The CaCl2 soil test proved markedly superior to H2SO4 as a predictive test for leaf Si levels. ©, © Taylor & Francis Group, LLC.

Dugmore T.J.,Environmental Affairs and Rural Development | Nsahlai I.V.,University of KwaZulu - Natal
South African Journal of Animal Sciences | Year: 2010

Digestion trials using sheep and voluntary feed intake (VFI) trials using long yearling heifers in Calan gates were conducted in the spring, summer and autumn over 5 years. These data and the chemical composition of the herbage were regressed on DMD and VFI. Excluding the mineral fractions, only three of the chemical components of the herbage emerged as important, namely, the DM content of the herbage as fed, accounting for 32% of the variance in DMD, the NPN content of the herbage accounting for only 12.2% of the variance and the ash content of the herbage accounting for 15.9% of the variance in digestibility. Of the macro-mineral components, Ca, Mg and P tended to be positively associated with DMD, while Na and K were significantly related to DMD. NDF was positively correlated to VFI, accounting for 37% of the variability in intake, while non-protein nitrogen was negatively correlated to VFI, although it did not account for much of the variability (11%) in VFI. Ca was also positively correlated to VFI, also accounting for very little of the variation in VFI (11.7%). Herbage Mg had a positive influence on VFI, accounting for 24% of the variation in VFI. Both DMD and VFI were highly negatively influenced by the moisture content of the herbage. © South African Society for Animal Science.

Dugmore T.J.,Environmental Affairs and Rural Development | Nsahlai I.V.,University of KwaZulu - Natal
South African Journal of Animal Sciences | Year: 2010

Digestion trials using sheep and voluntary feed intake (VFI) trials using long yearling heifers in Calan gates were conducted in the spring, summer and autumn. Five years of digestibility data, amounting to 82 digestion trials, was pooled for this study. Voluntary intake data was pooled for the three years of intake trials, amounting to 38 intake trials. These data and the daily maximum temperatures, rainfall and evaporation recorded at and prior to the digestion and intake trials at Cedara were pooled, analysed using multiple regression techniques, and regressed on dry matter digestibilty and VFI, to examine the influence of environment on the nutritive value of the herbage and to develop simple linear regression models for predicting kikuyu quality and intake. Rainfall and temperature in the period of cutting (plot preparation) and fertilization had a negative effect on digestibility, irrespective of the stage of re-growth at harvesting, 20, 30 or 40 days later, and a combination of the two proved significant, accounting for the most variance in DMD. Temperature depressed DMD by 28.1 g/kg DM per degree rise in temperature (°C). Temperatures recorded during the cutting and fertilization phase were highly negatively correlated to VFI, irrespective of stage of re-growth. © South African Society for Animal Science.

Taylor T.S.,University of KwaZulu - Natal | Titshall L.W.,University of KwaZulu - Natal | Titshall L.W.,Institute for Commercial Forestry Research | Hughes J.C.,University of KwaZulu - Natal | Thibaud G.R.,Environmental Affairs and Rural Development
South African Journal of Plant and Soil | Year: 2012

The effects of agricultural management practices on soil physical and biological parameters provide fundamental information for assessing sustainability. Tillage (annual conventional tillage and no-till) and nitrogen fertiliser (limestone ammonium nitrate at rates of 0,100 and 200 kg N ha -1) were evaluated for their effects on bulk density, water retention characteristics, saturated hydraulic conductivity, soil penetration resistance and microbiological activity (hydrolytic and cellulolytic) on a clay loam soil (Typic Haplustox) at a field experiment initiated in 2003 and planted to dryland maize. Tillage regime and nitrogen application rate significantly (p < 0.05) affected soil physical properties and microbial activity in the 0-5 cm layer. Under no-till the saturated water content and saturated hydraulic conductivity were significantly lower than under annual conventional tillage while plant available water was greater under no-till. Penetration resistance, bulk density and microbial activity were greater under no-till than annual conventional tillage. At 200 kg N ha-1 microbial activity, bulk density, water retention and saturated hydraulic conductivity were significantly lower than at the lower rates of application, especially under no-till. These results indicate that no-till improved soil physical properties and suggest there is a need to re-evaluate the sustainability of using high rates of nitrogen to increase maize yields, especially under a no-till system. Copyright © Combined Congress Continuing Committee.

Vatta A.F.,Ross University School of Medicine | de Villiers J.F.,Environmental Affairs and Rural Development | Harrison L.J.S.,University of Edinburgh | Krecek R.C.,Ross University School of Medicine | And 5 more authors.
Small Ruminant Research | Year: 2011

A series of studies were conducted, over a 10-year period (1998-2008), in KwaZulu-Natal, one of the poorest provinces in South Africa, involving on-farm research and extension and small-scale goat farmers. Initially, two farmers in the Impendle region participated, followed by nine farmers in Bulwer and latterly, 15 farmers in Bergville. The general aim was to develop an appropriate approach to improve goat health and productivity in the areas. A flexible framework for the acquisition of skills and knowledge was developed, which incorporated the use of the on-farm research project as a training vehicle. The farmers were trained in basic health care techniques such as drenching, injections and the use of the FAMACHA© system, a simple method for determining anaemia, a symptom of gastrointestinal nematode infection. Community-based workshops were used to strengthen the farmers' knowledge of animal diseases and their treatment. Extension materials were developed, including a "Goatkeepers' Animal Health Care Manual" The degree to which these participatory approaches helped increase community awareness of, and ability to deal with, goat health and management problems was assessed through questionnaire surveys conducted with participating and non-participating farmers and the general community. This new framework could equally well be applied more widely and to other agro-ecological zones. © 2011 Elsevier B.V.

Loading Environmental Affairs and Rural Development collaborators
Loading Environmental Affairs and Rural Development collaborators