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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
281

Effects of long- and short-term crop management on soil biological properties and nitrogen dynamics : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy at Lincoln University /

Stark, Christine, January 2005 (has links)
Thesis (Ph. D.) -- Lincoln University, 2005. / Also available via the World Wide Web.
282

Estimating the dry matter production, nitrogen requirements, and yield of organic farm-grown potatoes /

McQueen, John Paul Gainer. January 1900 (has links)
Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references. Also available on the World Wide Web.
283

Adoption of irrigation scheduling methods in South Africa

Stevens, Joseph Benjamin. January 2006 (has links)
Thesis (Ph.D.)(Agricultural Economics)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.
284

Dynamics of farmer adoption, adaptation, and management of soil conservation hedgerows in Haiti

Bannister, Michael E. January 2001 (has links)
Thesis (Ph. D.)--University of Florida, 2001. / Printout. Vita. Description based on print version record. Includes bibliographical references (leaves 218-234).
285

Saving Animals and the Land: Uniting the American Animal Rights and Environmental Movements of the Late Twentieth Century

Schmidt, Kelsey 01 August 2017 (has links)
The following research explores the growing stability of the relationship between the modern American animal rights and environmental movements in the aftermath of the 1960s counterculture. The movements have traditionally been considered by scholars in their separate contexts, because the movements had a tenuous and inconsistent relationship throughout their early histories. While the separate consideration of the movements may have been more appropriate for research prior to the 1960s, the movements became increasingly intertwined through various influences of the counterculture. The counterculture introduced new philosophies, utilitarianism and deep ecology, to the movements that united them through their mutual distaste for anthropocentrism and industrialization. The counterculture also provided animal rights and environmental advocates with alternative lifestyles with which to promote their goals and affect real change. The movements began to most clearly unite in their mutual campaigns against the intensive animal farming industry, more controversially and widely known as “factory farming.” Both movements utilized the philosophies introduced to their movements to argue against the moral ills of the industry. Hence, they identified a need to actively combat the effects of the meat industry and have since advocated a widespread adoption of the vegetarian lifestyle among the American public.
286

Local perceptions of environmental change in a tropical coastal wetland : the case of Koggala Lagoon, Galle, Sri Lanka

Samarasekara, Vidhisha Nayanthara January 1996 (has links)
Tropical coastal wetlands are under ecological stress, most notably due to accelerated development activities associated with these areas. Consequently, natural resource depletion and environmental problems in the coastal sector are increasingly serious issues, particularly in South and South East Asia, and have significant implications for their traditional resource-user groups. This thesis is primarily based on a detailed investigation of the inter-relationships between environmental change and local perception of change at Koggala, Galle, southern Sri Lanka, where six sample Divisions bordering Koggala Lagoon were selected for in-depth study. Multi-disciplinary techniques from both the natural and the social sciences were employed, focusing on the environmental changes involved and on the perceptions of these changes by local fishing and farming communities. Particular attention was paid to changes in agriculture, to the reconfiguration of a coastal sand bar, and to the development of a Free Trade Zone. Participatory techniques involved the experimental use of group discussions. Visits were made to Malaysia and Thailand for comparative study purposes. Results show that the fringing mangrove complex is currently threatened by a number of factors and that sand mining close to the lagoon outlet has severely disrupted water levels in the lagoon and ultimately rice-farming systems. The fishing community further perceives significant declines in their fish catch, attributing this to the loss of fishery nursery sites and to the seepage of agro-chemicals, some belonging to highly toxic groups, into the lagoon. It is clear that local communities display a high degree of awareness of environmental change, as well as of the causes of this change. Such understanding can be used to develop local-level adaptive planning for wetland management. The use of discussion groups is seen as a novel approach to such wetland management programmes in the tropics.
287

Agriculture and rural livelihoods in a South African 'homeland' : a case study from Venda

Lahiff, Edward Patrick January 1997 (has links)
This is a socio-economic study of agriculture and its contribution to livelihoods in Venda, one of the black 'homelands' created in South Africa under apartheid. It is based on a survey of households on the Tshiombo irrigation scheme, a project in central Venda with approximately six hundred plot-holders. The alms of the study are to understand the opportunities and constraints facing small farmers, and to suggest ways in which public action can promote rural livelihoods and overcome the legacy of racial oppression and under-development in South Africa. The study includes a review of micro-studies of agriculture and livelihoods from the ten former homelands. A range of unpublished materials and original field research are also used to provide an overview of society and economy in Venda at the end of apartheid and to highlight the problems faced by households attempting to secure a livelihood from the land. The Tshiombo case found that agriculture, on average, contributed approximately a quarter of household income (in cash and kind), with the balance coming mainly from wages and state pensions. Wide disparities were found between households, however, in terms of land-holding, agricultural output and overall household income. Relative poverty was associated with a lack of wage income and poorer households tended to be disproportionately dependent on agriculture. Both arable and livestock farming were dominated by older men, some of whom had a history of off-farm employment but others who had been full-time farmers since the 1960s. The study concludes that there is scope for further development of the agricultural economy at Tshiombo but this will require comprehensive reform of existing state services such as tractor ploughing and agricultural extension. More flexible partnerships between the state and non-state organisations, including private entrepreneurs, individual farmers and the struggling Tshiombo Co-operative in the provision of credit, marketing and transport services are also identified as areas suitable for development. Constraints of land, capital and household labour suggest that in most cases agriculture is likely to remain supplementary to income obtained from the non-farm economy, but can be a valuable source of food and an important safety-net in times of crisis.
288

Epidémiologie et évaluation quantitative du risque de broncho-pneumopathie chronique obstructive en milieu agricole / Epidemiology and quantitative evaluation of COPD's risk among farmers

Guillien, Alicia 11 June 2018 (has links)
La broncho-pneumopathie chronique obstructive (BPCO) est une maladie respiratoire grave, qui est le plus souvent secondaire à l’exposition à des substances toxiques inhalées. La fumée du tabac est le principal facteur de risque identifié mais certains milieux professionnels tels que les métiers agricoles sont associés à un risque accru de BPCO. Plusieurs études ont été menées ici avec pour objectifs (1) d’estimer la prévalence de BPCO dans plusieurs catégories de professions agricoles, (2) de créer un questionnaire de screening adapté au milieu agricole qui permettrait de pallier au sous-diagnostique de cette maladie en identifiant les sujets redevables d’un examen spirométrique et (3) d’étudier les facteurs deassociés à la BPCO en milieu agricole.La prévalence de la BPCO est environ deux fois plus importante en milieu agricole qu’en population générale. Néanmoins, cette prévalence est très variable selon la population d’étude (type d’activité, région d’exercice, caractéristiques de la ferme) et le critère de jugement utilisé (mesure pré- ou post-bronchodilatateur, critère GOLD ou LIN, prise en compte des symptômes), comme l’ont prouvé les résultats présentés ici.Une standardisation de la méthodologie pour les études épidémiologiques analysant le risque de BPCO en milieu agricole est donc nécessaire. Cette standardisation doit imposer un critère diagnostique robuste, une mesure de l’exposition la plus précise possible et l’inclusion d’un groupe de témoins sans exposition professionnelle. / Chronic obstructive pulmonary disease (COPD) is a severe disease that is in most cases secondary to the inhalation of noxious particles. Tobacco smoking is the main causal factor identified for this disease but some occupational exposures have also been associated with higher prevalence of COPD.The studies reported here aimed (1) to estimate the prevalence of COPD in the spectrum of agricultural works, (2) to develop a screening questionnaire appropriate to agricultural workers in order to identify subjects most likely to have COPD and (3) to study factors associated with COPD in farmers.The main findings are the following: prevalence of COPD is about twice higher in farmers than in the general population. However, this prevalence varies with study population (type of activity, region of exercise, characteristic of the farm) and the diagnostic criteria used (pre- or post-bronchodilator measure, criteria for airflow limitation, assessment of respiratory symptoms or not).It is concluded that standardization of the methodology used for epidemiologic investigations of COPD in farmers may be scheduled with (1) strong diagnostic criteria, (2) clear and robust measurement of occupational exposure and (3) inclusion of a control group of unexposed subjects.
289

The determination of Emamectin benzoate and its fate in the environment as a result of fish farming

Graham, Julie Edmonde January 2012 (has links)
The farming of Atlantic salmon (Salmo salar) is challenged by parasitic infestations caused by Lepeophthreirus salmonis and Caligus elongatus. A convenient and effective way to control sea lice and treat farmed salmon is by in-feed treatments such as Slice®. A reliable, accurate and reproducible method for the determination of emamectin benzoate (EB), the active ingredient of Slice®, and its desmethylamino metabolite (DES) in sediment was developed and validated. It involved methanolic extraction, clean-up using solid-phase extraction with a strong cation exchanger, and derivatisation with trifluoroacetic acid anhydride and N-methylimidazole. Analytes were quantified following HPLC separation with fluorescence detection. The method was successfully applied to determine EB and DES in salmon flesh and skin, seawater, mussels (Mytilus edulis) and seaweed (Palmaria palmata). A laboratory study showed that EB was persistent under anaerobic conditions in two different sediments at 4 and 14 ºC. A further study also demonstrated that the growth of seaweed (P. palmata) was not affected by the presence of EB and that EB did not accumulate significantly in the seaweed. This result is encouraging in view of proposed polyculture systems involving seaweeds. Studies conducted on a working Scottish salmon farm investigated the fate of EB and DES in target and non-target matrices. For three months post-treatment, EB was detected, by mass in descending order, in the salmon flesh, skin, faeces, then mucus and sea lice with concentrations in each matrix declining steadily over the period. As EB had never been quantified in sea lice before, it was unclear whether they were a significant sink for EB in the environment, following their exposure to the medicine and dislodging from salmon after feeding. However, due to the low concentrations of EB detected in the sea lice, faeces are most probably the main route for emamectin entering the environment. Sediment collected directly below and around two active walkways, over five or six months following treatment, showed that the spatial dispersion of EB and DES was mainly limited to the area within 25 m of the cage edge, although concentrations depended on sampling location in relation to water currents. Maximum EB concentrations were recorded three months after treatment. Seven days after treatment, 6 % of the total EB input was present in the sediments within 25 m of the cage edge. Neither EB nor DES were detected in seawater, mussels, periwinkles, dogwhelks and seaweed samples collected from the walkway and the surrounding environment. This work, one of the few studies of the uptake of EB by indigenous fauna and flora of an active salmon farm, suggests that it is not significantly accumulated in matrices outwith the target organism and the sediment.
290

Ajuste do fornecimento automático de ração de acordo com a temperatura da água para tilápias criadas em tanques rede / Adjustment of the automatic feed supply according to the water temperature for tilapia created in net tanks

Carmelin, Celio Aparecido [UNESP] 15 July 2018 (has links)
Submitted by Célio Aparecido Carmelin Júnior (celiomestre@gmail.com) on 2018-07-10T18:31:47Z No. of bitstreams: 1 tese final corrigida com ficha.pdf: 629321 bytes, checksum: ddbd36bb4fb86650c0001be1f8c96d04 (MD5) / Approved for entry into archive by Sulamita Selma C Colnago null (sulamita@btu.unesp.br) on 2018-07-16T16:59:10Z (GMT) No. of bitstreams: 1 carmelin_ca_dr_bot.pdf: 629321 bytes, checksum: ddbd36bb4fb86650c0001be1f8c96d04 (MD5) / Made available in DSpace on 2018-07-16T16:59:10Z (GMT). No. of bitstreams: 1 carmelin_ca_dr_bot.pdf: 629321 bytes, checksum: ddbd36bb4fb86650c0001be1f8c96d04 (MD5) Previous issue date: 2018-07-15 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O estudo teve como objetivo avaliar o fornecimento automático de ração em diferentes períodos para tilápias (Oreochromis niloticus), em diferentes situações ao longo do ano. Foram realizados dois trabalhos, o primeiro objetivou-se avaliar o desempenho de tilápias criadas sob efeito de altas temperaturas, em dois períodos diferentes, sendo o período 1 (0:00 ao 12:00hs) e o período 2 (12:00 a 24:00hs), entre os dias 15 de janeiro e 8 de março de 2017. Os melhores resultados para ganho de peso, peso total e peso médio foram encontrados nos peixes alimentados durante o período 1. Portanto, orienta-se fornecer o alimento, utilizando-se o sistema proposto, durante o período 1, para animais criados sob condições climáticas semelhantes às do experimento. O segundo trabalho teve como objetivo avaliar o desempenho de tilápias criadas sob efeito de baixas temperaturas, em três períodos diferentes, sendo o período 1, (0:00 ao 12:00hs) o período 2 (12:00 às 24:00hs) e o período 3 (0:00 às 24:00hs), entre os dias 4 de abril e 15 de julho de 2017. Os melhores resultados para ganho de peso e peso total foram obtidos pelos animais alimentados durante o período 2. O pior tratamento foi o período 1 e o período 3 foi intermediário. Portanto, orienta-se fornecer o alimento, utilizando-se o sistema proposto, durante o período 2, para animais criados sob condições climáticas semelhantes às do experimento. / The objective of this study was to evaluate the automatic feed supply in different periods for tilapia (Oreochromis niloticus), in different situations throughout the year. Two studies were carried out. The objective of the first study was to evaluate the performance of tilapia grown under high temperature conditions in two different periods: period 1 (0:00 to 12:00) and period 2 (12:00 to 24:00), between January 15 and March 8, 2017. The best results for weight gain, total weight and average weight were found in fish fed during period 1. Therefore, it is advised to provide the feed using the system proposed, during period 1, for animals reared under climatic conditions similar to those of the experiment. The second study had as objective to evaluate the performance of tilapia created under effect of low temperature, in three different periods, period 1 (0:00 to 12:00) period 2 (12:00 to 24:00) and the period 3 (0:00 to 24:00), from April 4 to July 15, 2017. The best results for weight gain and total weight were obtained by animals fed during period 2. The worst treatment was period 1 and period 3 was intermediate. Therefore, it is advised to provide the feed, using the proposed system, during period 2, for animals raised under climatic conditions similar to those of the experiment.

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