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The storage or disposal of nuclear waste is one of the major concerns faced by governments, communities, and environmentalists. This radioactive waste, as a source of ionising radiation, represents a potential hazard to human health and must be carefully managed so as to reduce the associated risks to acceptable levels for both now and in the future. The migration of radioactive waste (radionuclides) in the environment is controlled by many factors, such as the interaction of the radionuclides with soil. Humic acid (plant material) has substantial chelating properties for metal ions and can therefore considerably affect the migration behaviour of radionuclides in a soil layer. To manage the radioactive waste effectively, it is important to know the presence and interaction of humic acid with radionuclides released from radioactive waste repositories. The aim of this study is therefore to investigate the influence of humic acid on the distribution coefficients of radionuclides found in both Thabana and Vaalputs waste repositories. The technique employed in this study is based on a laboratory batch method to study the influence of humic acid on the distribution coefficients of (131)^I and (137)^Cs on soil samples from Thabana and Vallputs waste repositories at different concentrations. The results of this study show that (131)^I and (137)^Cs do not form any complexes with humic acid and therefore the presence of humic acid does not have a significant effect on the migration of (131)^I and (137)^Cs. / MSc (ARST) North-West University, Mafikeng Campus, 2005

Bibliography: p. 182-197. / xxii, 197 p. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / The objectives of this study are: selection and construction of four narrow sowing points, evaluation of these points in terms of draught requirements and wear rates, comparison of the points in direct drilling systems and their effects on soil physical properties. / Thesis (Ph.D.)--University of Adelaide, Dept. of Agronomy & Farming Systems (Agricultural Technology), 1997

Thesis (Ph. D. - Soils, Water and Engineering)--University of Arizona. / Includes bibliographical references.

Thesis (doctoral)--Christian-Albrechts-Universität zu Kiel, 1993. / Includes bibliographical references (p. 173-183).

Made available in DSpace on 2015-04-09T12:28:07Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-08-05Bitstream added on 2015-04-09T12:48:21Z : No. of bitstreams: 1 000819139.pdf: 734250 bytes, checksum: 8b3f27920a70ee1edcb62dd610d074cd (MD5) / As práticas agrícolas, com a modernização da agricultura, estão relacionadas com a utilização intensiva do solo e de maquinários; assim, o manejo do solo, visando sua menor degradação e maior sustentabilidade da agricultura, tem sido almejado por pesquisadores e agricultores. Os objetivos do presente trabalho foram avaliar a qualidade física de um Latossolo Vermelho distrófico típico, por parâmetros do solo, comparar a eficiência de quatro funções de pedotransferência para a curva de resistência do solo à penetração, por meio do ajuste de dados obtidos com o penetrômetro eletrônico sob os sistemas de manejo, semeadura direta e cultivo convencional, além de avaliar a produção das culturas do milho e da soja. O delineamento experimental foi o inteiramente casualizado, com parcelas subdivididas (sistemas de uso x camadas do solo), em seis repetições. Os tratamentos para a cultura do milho foram constituídos no solo de textura média sob semeadura direta, com 1; 8 e 10 anos consecutivos, e sob cultivo convencional e, também, no solo de textura argilosa sob semeadura direta, com 12 anos consecutivos, e sob cultivo convencional. Os tratamentos para a cultura da soja foram constituídos no solo de textura média sob semeadura direta com 2; 9 e 11 anos consecutivos, e sob cultivo convencional e no solo de textura argilosa sob semeadura direta, com 1 e 13 anos consecutivos, e sob cultivo convencional. A semeadura direta de 12 anos atingiu menor produção, em razão da formação de camadas compactadas, principalmente próximas à superfície do solo. O cultivo convencional, no solo de textura argilosa sob a cultura da soja, apresentou maior macroporosidade e porosidade total, além de menor densidade do solo, cuja produção apresentou valor superior, porém, não diferiu dos sistemas sob semeadura direta de dois e nove anos, sendo que os demais tratamentos não diferiram entre si. No solo de textura média, as ... / Agricultural practices and the modernization of agriculture are related to the use of intensive use of soil and machines, thus, the soil management, which aims to less degradation and more sustainable agriculture, have been sought by researchers, such as farmers. The objective of this study was to evaluate the physical quality of a typical Oxisol, through soil parameters and comparing the effect of four functions of pedotransfer for the curve of resistance to penetration, by tuning data obtained with penetrometer electronic management systems, no-tillage and conventional tillage, and evaluate the production of maize and soybeans. The experimental design was completely randomized split-plot (systems use x layers), in six replications. The treatments for maize were constituted by medium textured soil under no-tillage system, by 1; 8 and 10 consecutive years, and under conventional tillage, and the clay soil under no-tillage for 12 consecutive years, and under conventional tillage. Treatments for soybean were made by medium textured soil under no-tillage system, by 2; 9 and 11 consecutive years, and under conventional tillage and the clay soil under no-tillage, for 1 and 13 consecutive years, and under conventional tillage. The no tillage than 12 years, had lower production due to the formation of compacted layers, especially near the soil surface. The conventional tillage in clay soil under soybean had higher macroporosity and total porosity and lower density, whose production was higher, however, didn´t differ in no-tillage systems under two and nine years, and the other treatments didn´t have difference. In the soil of medium texture Equations RP = aUgb; RP = a (1-Ug)b; AebUg and RP = a + be-Ug/c showed similar precision and accuracy in predicting resistance to penetration. In the clayey soil Equations RP = a (1-Ug)b; RP = aebUg showed better performance

Made available in DSpace on 2014-06-11T19:35:16Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-08-23Bitstream added on 2014-06-13T20:06:57Z : No. of bitstreams: 1 nakayama_ft_dr_ilha.pdf: 450316 bytes, checksum: 082c50b94e8da5be2360a3aaf96e6438 (MD5) / Universidade Estadual Paulista (UNESP) / A semeadura direta vem a cada ano ampliando sua área agrícola no cerrado e é imprescindível a manutenção da palhada para o sucesso desta tecnologia, devendo respectivamente atender à necessidade da cultura e promover a conservação do solo. Desta forma, este trabalho teve por objetivo avaliar os efeitos do consórcio de plantas utilizadas como coberturas vegetais no desenvolvimento e produtividade do algodoeiro bem como sua contribuição no condicionamento químico e físico do solo. O delineamento experimental empregado foi o de blocos ao acaso com quatro repetições no esquema fatorial 4x4 compreendendo os fatores: 1. Dicotiledôneas: a- Cajanus cajan, b- Crotalaria juncea, c- Raphanus sativus, d- “sem dicotiledônea”; 2. Monocotiledôneas: a- Avena strigosa, b- Pennisetum glaucum, c- Brachiaria ruziziensis, d- “sem monocotiledônea”. Foram realizadas avaliações de fitomassa seca e cobertura do solo nas coberturas vegetais e a influência na química e física do solo sendo analisadas a porosidade e resistência à penetração. Após o manejo da palhada foi semeada a cultura do algodão nas parcelas experimentais no qual foram avaliados os aspectos agronômicos da cultura. De acordo com os resultados obtidos, os consórcios entre monocotiledôneas e dicotiledôneas ou ao cultivo exclusivo de monocotiledöneas apresentam maiores percentagens de cobertura do solo se comparado ao cultivo isolado de dicotiledôneas. As maiores produtividades de fitomassa seca de plantas de cobertura foram proporcionadas pelo cultivo exclusivo de milheto e milheto associado ao guandu. A aveia preta proporcionou os menores valores de resistëncia a penetraçäo para as camadas superficiais do solo (0-15 e 15-30 cm); e os tratamentos dicotiledonares destacando- se o nabo forrageiro proporcionaram uma diminuição... / The practice of no tillage are expanding year why year in Cerrado and is essential the crop residues maintenance for success of this technology, respectively meet the needs of culture and promote soil conservation. The objective work was to evaluate the effects of the consortium of cover crops in the development and yield of cotton as well as his contribution to the chemical and physical conditioning of the soil. The experimental design was a randomized block design with four replicates in a 4x4 factorial factors including: 1. Dicotyledons: a- Cajanus cajan, b- Crotalaria juncea, c- Raphanus sativus, d- “no dicotyledons”; 2. Monocotyledons: a- Avena strigosa, b- Pennisetum glaucum, c- Brachiaria ruziziensis, d- “no monocotyledons”. Were evaluated vegetation cover, dry matter and the influence on chemical and physical soil being analyzed porosity and penetration resistance. After handling of the cover crop was sown cotton in the experimental plots in which we evaluated the agronomic aspects of culture. According to the results obtained, the consortium between monocots and dicots or monocots unique culture have higher percentages of soil coverage as compared to isolated from dicotyledons. The highest yield of dry biomass of cover crops were provided exclusively by the cultivation of Pennisetum glaucum and Pennisetum glaucum associated with Cajanus cajan. The Avena strigosa provided the lowest values of penetration resistance to the soil surface layers (0-15 and 15-30 cm) and dicots treatments distinguished Raphanus sativus provided a decrease in penetration resistance for layers 30 -45 and 45-60 cm. Pennisetum glaucum provided the highest values for total porosity and macroporosity in the 0-20 cm layer. Treatments isolated Raphanus sativus, Raphanus sativus associated Brachiaria ruziziensis or until Pennisetum glaucum sown in the month of July provided the highest yield for Deltaopal cotton in the Cerrado conditions

Made available in DSpace on 2015-08-20T17:10:17Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-05-22. Added 1 bitstream(s) on 2015-08-20T17:25:38Z : No. of bitstreams: 1 000844821.pdf: 4286777 bytes, checksum: 97c5ecfbba0024069834d0e7df200d66 (MD5) / As modificações causadas por atividades antrópicas como o tráfego de máquinas afetam diretamente a estrutura do solo, por isto, a importância de avaliar a compactação do solo devido ao tráfego agrícola, assim como a magnitude dos impactos do rodado sobre a qualidade física dos solos. O trabalho teve por objetivo avaliar a influência do teor de agua na avaliação de resistência mecânica a penetração do solo medida através do índice de cone (IC), a ocorrência e distribuição da compactação ao longo do perfil do solo causada pelo trafego agrícola, assim como os consequentes reflexos nos atributos físicos do solo. O experimento foi realizado na Fazenda Lageado da UNESP/FCA, Botucatu/SP, sendo selecionadas duas classes de solo, o Nitossolo Vermelho distroférrico (NVd) de textura argilosa, com 50 % de teor de argila e o Latossolo Vermelho (LV) de textura média, com 25 % de teor de argila. O delineamento experimental foi casualizado, com os seguintes tratamentos de compactação: T0 = 0; T1 = 1; T2 = 2; T3 = 3; T4=5 e T5 = 10 passadas consecutivas de um trator agrícola. Utilizou-se um penetrômetro hidráulicoeletrônico para a amostragem da resistência mecânica do solo a penetração nas camadas de 0 a 0,10; 0,10 a 0,20; 0,20 a 0,30; 0,30 a 0,40m em 4 condições de teor de água, que variou de 17,1 a 24,5% para o NVd e de 10,0 a 17,8% para o LV. Também foram determinados os seguintes atributos: recalque do solo, infiltração de água no solo... / The changes caused by human activities such as machinery traffic directly affect soil structure, therefore, the importance of assessing soil compaction due to agricultural traffic, as well as the magnitude of the impact of the wheelset on the physical quality of the soil. The study aimed to evaluate the influence of water content in soil penetration resistance evaluation measured by the soil Cone Index (CI), the occurrence and distribution of compression along the soil profile, caused by agricultural traffic, as well as the resulting consequences on soil physical properties. The experiment area was at Lageado Experimental Farm, UNESP/FCA, Botucatu/São Paulo, two different soil type was used, Nitossolo Vermelho distroférrico (NVd) clayey, 50% clay content and Latossolo Vermelho (LV) of medium texture, 25% clay content. Was used an randomized experimental design with the following compaction treatments: T0 = 0; T1 = 1; T2 = 2; T3 = 3; T4= 5 and T5 = 10 consecutive passes of an tractor. An hydraulic-electronic penetrometer was used to measure the soil resistance at 0-0.10; 0.10-0.20; 0.20-0.30 and 0.30-0.40 m in 4 different water content ranging from 17.1 to 24.5% for NVD and 10 to 17.8% for LV. It was also determined the following attributes: soil repression, water infiltration into the soil, bulk density and porosity. The major soil penetration resistance values were detected near the ground shrinkage limit and the treatment with increased intensity agricultural traffic, already in high moisture soil conditions, the soil penetration resistance values were reduced being considered not hindering the growth of roots. The clay soil proved to be the most sensitive to the effect of water content in soil compaction evaluation, the greater variation among samples collected with water content between field capacity (FC) and permanent wilting point (PWP) ...

Orientador: Enes Furlani Júnior / Banca: Salatiér Buzetti / Banca: Marco Eustaquio de Sa / Banca: José Carlos Cavichioli / Banca: Edivaldo Cia / Resumo: A semeadura direta vem a cada ano ampliando sua área agrícola no cerrado e é imprescindível a manutenção da palhada para o sucesso desta tecnologia, devendo respectivamente atender à necessidade da cultura e promover a conservação do solo. Desta forma, este trabalho teve por objetivo avaliar os efeitos do consórcio de plantas utilizadas como coberturas vegetais no desenvolvimento e produtividade do algodoeiro bem como sua contribuição no condicionamento químico e físico do solo. O delineamento experimental empregado foi o de blocos ao acaso com quatro repetições no esquema fatorial 4x4 compreendendo os fatores: 1. Dicotiledôneas: a- Cajanus cajan, b- Crotalaria juncea, c- Raphanus sativus, d- "sem dicotiledônea"; 2. Monocotiledôneas: a- Avena strigosa, b- Pennisetum glaucum, c- Brachiaria ruziziensis, d- "sem monocotiledônea". Foram realizadas avaliações de fitomassa seca e cobertura do solo nas coberturas vegetais e a influência na química e física do solo sendo analisadas a porosidade e resistência à penetração. Após o manejo da palhada foi semeada a cultura do algodão nas parcelas experimentais no qual foram avaliados os aspectos agronômicos da cultura. De acordo com os resultados obtidos, os consórcios entre monocotiledôneas e dicotiledôneas ou ao cultivo exclusivo de monocotiledöneas apresentam maiores percentagens de cobertura do solo se comparado ao cultivo isolado de dicotiledôneas. As maiores produtividades de fitomassa seca de plantas de cobertura foram proporcionadas pelo cultivo exclusivo de milheto e milheto associado ao guandu. A aveia preta proporcionou os menores valores de resistëncia a penetraçäo para as camadas superficiais do solo (0-15 e 15-30 cm); e os tratamentos dicotiledonares destacando- se o nabo forrageiro proporcionaram uma diminuição... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The practice of no tillage are expanding year why year in Cerrado and is essential the crop residues maintenance for success of this technology, respectively meet the needs of culture and promote soil conservation. The objective work was to evaluate the effects of the consortium of cover crops in the development and yield of cotton as well as his contribution to the chemical and physical conditioning of the soil. The experimental design was a randomized block design with four replicates in a 4x4 factorial factors including: 1. Dicotyledons: a- Cajanus cajan, b- Crotalaria juncea, c- Raphanus sativus, d- "no dicotyledons"; 2. Monocotyledons: a- Avena strigosa, b- Pennisetum glaucum, c- Brachiaria ruziziensis, d- "no monocotyledons". Were evaluated vegetation cover, dry matter and the influence on chemical and physical soil being analyzed porosity and penetration resistance. After handling of the cover crop was sown cotton in the experimental plots in which we evaluated the agronomic aspects of culture. According to the results obtained, the consortium between monocots and dicots or monocots unique culture have higher percentages of soil coverage as compared to isolated from dicotyledons. The highest yield of dry biomass of cover crops were provided exclusively by the cultivation of Pennisetum glaucum and Pennisetum glaucum associated with Cajanus cajan. The Avena strigosa provided the lowest values of penetration resistance to the soil surface layers (0-15 and 15-30 cm) and dicots treatments distinguished Raphanus sativus provided a decrease in penetration resistance for layers 30 -45 and 45-60 cm. Pennisetum glaucum provided the highest values for total porosity and macroporosity in the 0-20 cm layer. Treatments isolated Raphanus sativus, Raphanus sativus associated Brachiaria ruziziensis or until Pennisetum glaucum sown in the month of July provided the highest yield for Deltaopal cotton in the Cerrado conditions / Doutor

Orientador: Kleber Pereira Lanças / Banca: Maria Helena Moraes / Banca: Marlene Cristina Alves / Resumo: As modificações causadas por atividades antrópicas como o tráfego de máquinas afetam diretamente a estrutura do solo, por isto, a importância de avaliar a compactação do solo devido ao tráfego agrícola, assim como a magnitude dos impactos do rodado sobre a qualidade física dos solos. O trabalho teve por objetivo avaliar a influência do teor de agua na avaliação de resistência mecânica a penetração do solo medida através do índice de cone (IC), a ocorrência e distribuição da compactação ao longo do perfil do solo causada pelo trafego agrícola, assim como os consequentes reflexos nos atributos físicos do solo. O experimento foi realizado na Fazenda Lageado da UNESP/FCA, Botucatu/SP, sendo selecionadas duas classes de solo, o Nitossolo Vermelho distroférrico (NVd) de textura argilosa, com 50 % de teor de argila e o Latossolo Vermelho (LV) de textura média, com 25 % de teor de argila. O delineamento experimental foi casualizado, com os seguintes tratamentos de compactação: T0 = 0; T1 = 1; T2 = 2; T3 = 3; T4=5 e T5 = 10 passadas consecutivas de um trator agrícola. Utilizou-se um penetrômetro hidráulicoeletrônico para a amostragem da resistência mecânica do solo a penetração nas camadas de 0 a 0,10; 0,10 a 0,20; 0,20 a 0,30; 0,30 a 0,40m em 4 condições de teor de água, que variou de 17,1 a 24,5% para o NVd e de 10,0 a 17,8% para o LV. Também foram determinados os seguintes atributos: recalque do solo, infiltração de água no solo... / Abstract: The changes caused by human activities such as machinery traffic directly affect soil structure, therefore, the importance of assessing soil compaction due to agricultural traffic, as well as the magnitude of the impact of the wheelset on the physical quality of the soil. The study aimed to evaluate the influence of water content in soil penetration resistance evaluation measured by the soil Cone Index (CI), the occurrence and distribution of compression along the soil profile, caused by agricultural traffic, as well as the resulting consequences on soil physical properties. The experiment area was at Lageado Experimental Farm, UNESP/FCA, Botucatu/São Paulo, two different soil type was used, Nitossolo Vermelho distroférrico (NVd) clayey, 50% clay content and Latossolo Vermelho (LV) of medium texture, 25% clay content. Was used an randomized experimental design with the following compaction treatments: T0 = 0; T1 = 1; T2 = 2; T3 = 3; T4= 5 and T5 = 10 consecutive passes of an tractor. An hydraulic-electronic penetrometer was used to measure the soil resistance at 0-0.10; 0.10-0.20; 0.20-0.30 and 0.30-0.40 m in 4 different water content ranging from 17.1 to 24.5% for NVD and 10 to 17.8% for LV. It was also determined the following attributes: soil repression, water infiltration into the soil, bulk density and porosity. The major soil penetration resistance values were detected near the ground shrinkage limit and the treatment with increased intensity agricultural traffic, already in high moisture soil conditions, the soil penetration resistance values were reduced being considered not hindering the growth of roots. The clay soil proved to be the most sensitive to the effect of water content in soil compaction evaluation, the greater variation among samples collected with water content between field capacity (FC) and permanent wilting point (PWP) ... / Mestre