An investigation into land capability classification in Eritrea : the case study of Asmara city environs.

Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.The problems of land resources degradation as a result of misuse of arable land for non agricultural development and lack of appropriate methods and guidelines for land resources assessment are currently evident in Eritrea. These problems, have called for an urgent need for an appropriate land resources assessment in Eritrea. In response to this, a land capability classification in the areas around Asmara city that covers about 11742.7 ha was conducted. The intended aim was to properly assess the potential of the land resources in the study area and classify the capability of the land so as to designate the land according to its capability and foster appropriate land use. All the available natural resources in the study area were carefully assessed. A detailed soil survey was conducted and soil units were examined, described, classified and mapped out. Several criteria for the limitations were selected from the reviewed literature mainly USDA and RSA Land Capability Classification systems and in consultation with the soil survey and natural resources experts of the Ministry of Agriculture in Eritrea. In formation on land and soil characteristics, and the specified limitations and criteria were captured in a spatial digital format and then analysed within a GIS. Based on the specified parameters, different land capability units, subclasses, classes and orders were identified and mapped out. Finally, the sub classes were grouped to create,land capability classes ranging from Class I to Class VII and consequently the capability classes were grouped and mapped out at the level of land capability orders. The results revealed seven land capability classes (Class I to VII). Class III land in the study area covers 4149.43 ha (36.9 percent of the total area). The largest portion of this class is found in the central, southern and south eastern parts of the study area. However, classes I and II are very limited and cover 1562.95 ha (13.9 percent) of the study area. These classes are found mainly in the southern and central parts of the study area. Most of the gentle and steep sloping lands in the north and north eastern parts of the study area are classified as classes IV and VI. These classes have an area of 2652.08 ha (23.6 percent) and 2594.87 ha (23.1 percent) of the study area, respectively. Classes V and VII are very limited. These classes cover 221.53 ha (2 percent) and 57.55 ha (0.5 percent), respectively. The largest portion of class V land is found in the central part of the study area. Class VII land is mainly confined to the north eastern, western and southern corners of the study area. Four land capability orders were arrived at ranging from (high to moderate potential to non-arable land). The high to moderate potential arable lands are largely found in the southern and central parts of the study area. These lands cover 5715.39 ha (50.8 percent) of the study area. However, low potential arable (marginal productive) and non-arable lands have a considerable area of 2652.08 ha (23.6 percent) and 2652.42 ha (23.1 percent) of the study area, respectively. The largest portion of these lands is found in the north, north eastern and eastern parts of the study area. A small portion of the lands in the study area is classified as seasonally wetland. This land has an are~\ of 221.53 h~{2 percent) of the study area and is mainly found in the central part of the study area. It was concluded that nearly 50 percent of the land in the study area is classified as of moderately to high agricultural potential whereas the rest of the land is classified as marginal to non-arable land. However, the steady growth of demand for land for nonagricultural development due to the increasing population that depend on farm production in the study area, renders the prime arable lands as too limited to support the current population in the study area. Hence, protecting the prime arable lands and properly using such lands based on their sustained capacity can only secure the livelihood of the community

The effects of silicon level in nutrient solution on the uptake and distribution of silicon in zucchini and zinnia, and its interaction with the uptake of selected elements

The beneficial role of silicon (Si) in the growth of some plants is linked to its uptake and accumulation inside their tissue. However, the optimum level of Si in the nutrient solution that can provide maximum benefits and its interaction with other elements is less understood. A study was conducted to evaluate the impact of different levels of soluble Si in nutrient solutions on the uptake and distribution of Si and other elements into different parts of zucchini and zinnia, and its effects on the growth of these two plants. Increasing the concentrations of Si in the nutrient solution increased the accumulation of Si (in leaves and roots) and potassium (in stem and petiole) and reduced calcium without affecting the levels of magnesium and phosphorus in different organs of both plants. Application of Si at 50 mg L-1 resulted in maximal accumulations of P, Ca and Mg in both plants and increased their growth. However, the application of higher levels of Si caused stunting. For optimal benefits, application of Si at 50 to 100 mg L-1 is recommended for these plants.Keywords: Accumulation, distribution, growth, silicon, uptake, zinnia, zucchiniAfrican Journal of Biotechnology Vol. 12(14), pp. 1617-162

Economic evaluation of anaerobic digestion technology

Abstract: This paper evaluates the viability of anaerobic digestion technology as a treatment process for organic waste with an intention of solving the landfill crisis as well as mitigation of greenhouse gases. The proposed technology consists of two digesters system using soaking as a pre-treatment method, and with recirculation of the process water and digested sludge. A financial model was developed to evaluate the economic feasibility of this technology as a renewable energy. Instead of the waste decomposing at local landfills, is converted into a source of energy while the byproducts of the process are treated and used as fertilizers. This technology will require a capital investment of R 2, 2773,900 with a capacity to treat 730000 kg of waste annually. The annual production cost of R1, 269,138 was calculated. The proposed model has debt repayments of R 2,478,551. The total revenue from year 2 – 5 was R 2,360,800, R 2,930,158, R 3,457,314.6 and R 3,988,407.6, respectively. These AD facilities can produce up to 110960 kWh per annum of biogas fuel. The net present value of R3, 042,592, internal rate of return (IRR) of 33% and (BCR) of 1.96 shows that the technology is economically feasible

Effect of particle size on anaerobic digestion of different feedstocks

The speed and stability of anaerobic digestion depends mainly on the particle size of the input material. In this paper, particle sizes of 500μm, 250μm, 100μm and 25μm were investigated to evaluate the effects of particle size on biogas production and identify the most suitable size that would improve the efficiency of anaerobic digestion. The study was conducted using anaerobic digestion batch scale tests and gas chromatography to investigate the quality of the gas produced and the optimum particle size to maximise methane production. Prior digestion, the distributions of particle sizes of all samples were determined using single and double pass distribution techniques. 59%, 53%, 33% and 39% of CD, CM, PM and SW were recovered, respectively. In both techniques, the weight of the feed recovered reduced as the sieve became smaller. Decreasing the particle size of the feedstock significantly increased the amount of biogas. At 25μm particle size, 583ml, 569ml, 538ml and 398ml of methane was produced on the 4th day of gas production for CD, PM, CM and SW, respectively. At optimal particle size (25μm) methane was 3 – 30 % higher as compared to that of 100μm, 250μm and 500μm particle size in mesophillic batch digestion tests

Economic evaluation of anaerobic digestion technology

Abstract: This paper evaluates the viability of anaerobic digestion technology as a treatment process for organic waste with an intention of solving the landfill crisis as well as mitigation of greenhouse gases. The proposed technology consists of two digesters system using soaking as a pre-treatment method, and with recirculation of the process water and digested sludge. A financial model was developed to evaluate the economic feasibility of this technology as a renewable energy. Instead of the waste decomposing at local landfills, is converted into a source of energy while the by-products of the process are treated and used as fertilizers. This technology will require a capital investment of R 2, 2773,900 with a capacity to treat 730000 kg of waste annually. The annual production cost of R1, 269,138 was calculated. The proposed model has debt repayments of R 2,478,551. The total revenue from year 2 – 5 was R 2,360,800, R 2,930,158, R 3,457,314.6 and R 3,988,407.6, respectively. These AD facilities can produce up to 110960 kWh per annum of biogas fuel. The net present value of R3, 042,592, internal rate of return (IRR) of 33% and (BCR) of 1.96 shows that the technology is economically feasible

Alternative application methods of antagonists to avocado flowers to control stem-end rot pathogens

Biological pre- and postharvest disease control strategies depend on successful colonisation and survival of the introduced antagonists on the infection court. Effective and economical applications involve targeting the antagonists where they are critically needed i.e. the infection court. Honeybee dispersal is one method of antagonist application to such specific sites. In view of this, an in vitro experiment was conducted to investigate attachment, colonisation and survival of Bacillus subtilis on avocado flowers. Scanning electron microscopy studies showed that the bacterium could attach and colonise avocado flower surfaces. It can also survive on the flowers for longer periods of time. In vivo mode of action of the antagonist against stem-end rot (SER) pathogens was also studied where results showed lysis and degradation of hyphae and conidia. However, no viable colonies were retrieved from bee antagonist dispersal under field conditions. Bee antagonist dissemination was compared with antagonist and fungicide spray applications in terms of SER control and the added effect on other diseases such as Cercospora spot and anthracnose. Spray applications of the antagonist were more effective in reducing the incidence of SER than bee dissemination. Integrated sprays of the antagonist and fungicides significantly reduced the incidence of both pre- and postharvest diseases. The identity of Dothiorella aromatica, one of the most important SER pathogens, was investigated at a molecular level. RAPD techniques using the discriminatory OPC02 primer successfully separated isolates into three groups based on banding profiles. A further study using RFLP identified the pathogen as a Botryosphaeria spp. The most dominant specie was B. parva followed by B. rhodina. Further studies should focus on assessing the distribution of these pathogens within avocado-growing regions of South Africa.Dissertation (MSc (Plant Pathology))--University of Pretoria, 2006.Microbiology and Plant Pathologyunrestricte

Chemical absorption of carbon dioxide in biogas purification

Abstract: Biogas is produced from anaerobic digestion of organic biodegradable materials. However, its application is limited as it contains impurities such as carbon dioxide (CO2), hydrogen sulphide (H2S), and other trace gases. Chemical absorption is capable of producing gas of high methane content above 95% and has no methane losses hence it’s widely used on large scale applications. Sodium hydroxide was used for cleaning the biogas in this study at a concentration of 1M, 2M, and 3M. The effect of concentration on absorption and CO2 removal efficiency was studied. It was observed that an increase in concentration lead to an increase in the absorption rate and the removal efficiency respectively. The highest removal efficiency was recorded to be 66%

Meningeal B cells in central nervous system autoimmunity: Their phenotype and susceptibility to therapeutic depletion

B cell depleting therapies have been effective in the treatment of Multiple Sclerosis (MS), yet to date little is known about how B cells promote disease pathogenesis. B cells can be found invading the meninges around the brain and spinal cord in MS, where they cluster in association with T cells. These meningeal B cells clusters are often adjacent to demyelinating lesions suggesting this may be a site where B cells are exerting their pathogenic effects. The purpose of this thesis was to understand the contribution of meningeal B cells to central nervous system (CNS) autoimmunity, by characterizing their phenotype and determining their susceptibility to B cell depletion. Using an animal model of MS, immunofluorescence analysis, flow cytometry, or single-cell sequencing analysis was used to analyze B cells within the inflamed CNS. Interestingly, while anti-myelin T cells were readily identified in the inflamed CNS, anti-myelin B cells were excluded from this site. Non-specific B cells within the CNS were phenotypically unique from naïve B cells, exhibiting a non-classical activation status. Following treatment with anti-CD20, B cells were rapidly depleted in peripheral tissues such as the blood, lymph node and spleen, while depletion in the CNS was delayed. Following treatment there was minimal evidence that anti-CD20 accessed meningeal B cells directly, but rather that depletion was indirect and the result of ongoing turnover of the meningeal population and elimination of the peripheral pool from which it is sustained. Depleting B cells from the CNS resulted in significantly less demyelination and T cell accumulation within meningeal clusters. This suggests that B cells may be required to help with T cell reactivation within the meninges, and that depletion of B cells over time prevents ongoing local pathology. Collectively, this thesis elucidates the phenotype of B cells within the inflamed CNS of anti-myelin autoimmunity, supporting a role for their involvement in disease pathogenesis. By selectively targeting pathogenic populations of B cells this will help minimize the adverse effects that exist with current complete B cell depletion therapies

Evaluation of Germplasm of Pearl Millet (Penissetum glaucum L.) for Agronomic, Physiological and Biochemical Traits under Semi-arid Conditions of Hamelmalo

A field experiment was conducted at the experimental farm of Hamelmalo Agricultural College during summer 2017, to evaluate the agronomic, physiological, and biochemical performance of the collected Eritrean germplasm of pearl millet. A total of 16 accessions were tested, out of which 2 were improved varieties included as a check. The experiment was laid out in 4 x 4 Simple Lattice Design with Randomized Block using 4 replications with a gross plot size of 3.0 m x 1.2 m, row to row spacing of 75 cm and plant to plant spacing of 30 cm. The data collected were Agronomic parameters (growth, development, yield, and yield contributing characters); Physiological parameters (Relative water content and Water Use Efficiency); and Biochemical parameters (crude fat, crude fiber, protein content, TSS, and ash content). The data were analyzed using GENSTAT software and correlation analysis was worked to see the positive and negative contribution of agronomic, physiological, and biochemical attributes. The results of the study showed that Bariyay908 and Kona being statistically at par with Bariyay 910, Hagaz, Zibedi, Shleti, Delkata, Tokroray, and Kunama produced significantly higher grain yield. However, among these Baryay908 because of its superior agronomic characteristics, lower incidence of downy mildew, relatively higher water use efficiency and higher crude protein content were found to be comparatively superior to the check improved varieties Kona and Hagaz. Grain yield has shown a positive and significant correlation with harvest index, number of seeds per panicle, panicle length, leaf area and water use efficiency. These promising accessions need to be further tested for future breeding programs to develop varieties higher in productivity and resistant to downy mildew under semiarid conditions of Eritrea

Value creation and enhancement : case study of Red Sea Bottlers Share Company in Eritrea.

Thesis (MBA)-University of Natal, 2004.The problem addressed in this research is to assess and analyse what actions lead to value creation and enhancement in Red Sea Bottlers Share Company. This research problem is broken down into three basic objectives namely: determining the value drivers of the company, evaluating how and to what extent the company is creating or destroying value, and evaluating what the management is doing in enhancing the value of the company. Company annual financial statements and other secondary documents were used to collect data for the second objective and Questionnaire was used for the first and third objectives. Seven Value drivers of Rappaport's framework are used to ascertain what managers are doing to enhance the value of the company. According to the study to increase revenue managers will increase local sales, strengthen marketing, establish local sales offices and advertise the products. Similarly to increase the profit margin building employees' morale by increasing wages and salaries, being more selective to suppliers, effectively use of resources, increasing product quality and improving production efficiency are being undertaken by managers. There is no visible attempt to reduce the tax expense. As far as the investment decision is concerned, renovating and maintaining the fixed assets has been done. There is no visible value enhancing measure in the working capital management except in inventory management. In relation to the financing decision the company is not using any long-term liability and is lacking the advantage of its gearing effect. Last, as to the growth duration of the value the company's brand name, high capital investment and established distribution channels could be mentioned as entry barriers to potential entrants and become factors of lengthening the value growth duration. Overall what the managers are doing in enhancing the company's value is positive and is to be promoted and encouraged. The main performance measurement tools recommended to determine whether the company is creating value or not are the multi-period measurement tool Total Business Return and the single period tool Economic Value Added. According to these measurements the company is creating value as per the measure of Total Business Return and destroying value as per the measure of Economic Value Added