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O presente trabalho apresenta um estudo das condições geotécnicas e do monitoramento da obra de ampliação dos molhes, proteção da entrada do canal de navegação do Porto de Rio Grande-RS/ Brasil, assente em solos moles. Atenção é dada a problemas associados à capacidade de carga e recalque das fundações. Investigações indicaram que o solo de fundação é constituído de uma camada de areia com 3 a 5 m de espessura abaixo do piso marinho, seguida de camada de argila mole, com índice NSPT de 2 a 4 e espessura média de 15 m. Somente abaixo dessa profundidade ocorrem solos de maior resistência. Deste modo, antecipou-se no projeto que as camadas do subsolo marinho iriam sofrer recalques e deslocamentos significativos quando submetidas às cargas decorrentes do alteamento dos molhes, havendo a necessidade de garantir as condições de estabilidade a partir da construção de bermas de equilibrio. Devido aos riscos, a obra foi concebida como observacional, sendo acompanhada de instrumentação de controle do processo construtivo, incluindo a observação das poro-pressões, recalques e deslocamentos horizontais na camada de argila mole, compressível e de baixa resistência. A instrumentação implantada na obra inclui inclinômetros, medidores do tipo aranha e piezômetros, sendo tal instrumentação pioneira no Brasil em obras nearshore, pois devido às condições marítimas adversas, parte dos instrumentos envia os dados via rádio, com monitoramento contínuo em tempo real. Este trabalho apresenta relatos das etapas da obra, incluindo a investigação das condições do subsolo e a instalação da instrumentação, constituindo-se igualmente em um desafio devido à profundidade, às restrições de acesso, ventos, impacto de ondas e correntes. Os resultados da instrumentação foram analisados e sistemas de alerta foram implantados para garantir as condições de segurança durante todas as etapas construtivas dos molhes. / The present work presents the study of the geotechnical conditions and the monitoring of the breakwaters enlargement work in Rio Grande-RS/Brazil. The breakwaters are the protection for the Rio Grande harbor channel, based on soft soils. Focus is given to problems associated to the load and settlements of the foundations. Investigations have indicated that the soil is constituted of a 3 to 5 meter thick sand layer under the sea floor, followed by a soft clay layer with NSPT between 2 and 4 and 15 meter average thick. Only under this depth soils with larger strength occur. Therefore, it was predicted in the project that the layers from the sea subsoil would experience considerable settlements and displacements when they undergo the loads from the breakwaters heightening, existing the need to ensure stability conditions with the construction of balance berms. Due to risks, the work was conceived as observational and it has been accompanied by a control instrumentation of the constructive process, including pore water pressure observations as well as horizontal and vertical displacements in the clay layer. The implemented instrumentation includes inclinometers, spider magnet meters and piezometers. The use of these instrumentations has been considered pioneer in nearshore works in Brazil because, due to the adverse sea conditions, part of them send data by radio signal, with continuous monitoring on real time. This work presents reports from the steps taken in the work, including the investigation of the subsoil conditions and the installation of the instrumentation, which had constituted a challenge due to the depth, access restriction, wind, wave impact and the sea flow. Instrumentation results were analyzed and alert systems were deployed to ensure safety conditions during all the constructive steps of the breakwaters.

In tropical and subtropical areas, especially, where there is the dry period occurrence, the acidity subsurface (below the 10 cm) it has been pointed as one of the limitation causes to the growth of roots and the agricultural productivity. In the state of Rio Grande do Sul, in the last years, reports exist that areas under no tillage that don't present exchangeable aluminum in the layer of 0-10 cm. However, in the inferior layers, they are found high content of Al and low saturation by bases (Martinazzo, 2006). However, information that allows inferring about the relevance of these conditions in subsurface in the productivity of the cultures doesn t exist. This work was elaborated with the objective of evaluating the occurrence of high saturation with aluminum and low saturation with bases, in subsurface in the no tillage, it can represent a restrictive atmosphere for the growth and productivity of the cultures, as well as to evaluate techniques for correction of the acidity in subsurface. The experiment was implanted in Tupanciretã, RS, in Rhodic Hapludox, of sandy loam texture. The area came being driven under no tillage, and the initial condition, in the layer of 0-10 cm was of pH 5,5, saturation for Al of 0% and saturation of bases of 65%; in the layer of 10-20 cm it presented pH 5,1, saturation for Al of 24% and saturation for bases of 39%. In July of 2005, the following treatments were implanted: without tillage and without limestone; without tillage and with limestone, 1 SMP - pH 6,0; plowing without limestone; plowing with limestone, 1 SMP - pH 6,0; chiseling without limestone; chiseling, with limestone, 1 SMP - pH 6,0; based on the sample of 0-20 cm. The accomplished evaluations were: productivity of grains, matter dries, cycling of nutrients (Ca, Mg, P, K e N) distribution of the system root and economical analysis for the soybean (Glycine max L. Merril) and the corn (Zea mays L.). In soil samples collected to the 9 and 24 months after the implantation of the experiment, in the layers of 0-5; 5-10; 10-15; 15-20; 20-30 cm, they were certain the exchangeable content of Ca, Mg and Al, pH H2O, saturation for bases and saturation for Al, besides the content of P and K and organic carbon. All the variables were submitted to the analysis of the variance and when significant, the averages were compared by the test of Tukey to 5%. The results show that acidity in subsurface (10-20 cm) it was not limit to the productivity of the soybean and of the corn when the superficial layer was in levels recommended by CQFS-RS/SC (2004), what didn't allow the definition in the best way of limestone application under the point of view of productivity of grains and economical viability, however, the limestone incorporation for plowing was the most efficient way of correction of the acidity in subsurface. / Em regiões tropicais e subtropicais, especialmente onde há a ocorrência de veranicos, a acidez subsuperficial (abaixo dos 10 cm) tem sido apontada como uma das causas de limitação ao crescimento de raízes e à produtividade agrícola. No estado do Rio Grande do Sul, nos últimos anos, existem relatos de que muitas áreas sob plantio direto não apresentam alumínio trocável na camada de 0-10 cm, mas nas camadas inferiores, são encontrados elevados teores de Al e baixa saturação por bases. Contudo, não existem informações que permitem inferir sobre a relevância destas condições em subsuperfície na produtividade das culturas. Este trabalho foi elaborado com o objetivo de avaliar se a ocorrência de alta saturação por alumínio e baixa saturação por bases em subsuperfície no plantio direto, pode representar um ambiente restritivo para o crescimento e produtividade das culturas, bem como avaliar técnicas para correção da acidez em subsuperfície. O experimento foi implantado em Tupanciretã, RS, em um Latossolo Vermelho distrófico típico (Embrapa, 2006), de textura franco-arenosa. A área vinha sendo conduzida sob plantio direto, sendo que a condição inicial, na camada de 0-10 cm era de pH 5,5, saturação por Al de 0% e saturação de bases de 65%; na camada de 10-20 cm apresentava pH 5,1, saturação por Al de 24% e saturação por bases de 39%. Em julho de 2005 foram implantados os seguintes tratamentos: sem revolvimento e sem calcário; sem revolvimento e com calcário, 1 SMP - pH 6,0; lavração sem calcário; lavração com calcário, 1 SMP - pH 6,0; escarificação sem calcário; escarificação com calcário, 1 SMP - pH 6,0; baseado na amostra de 0-20 cm. As avaliações realizadas foram: produção de matéria seca, ciclagem de nutrientes (Ca, Mg, P, K e N), produtividade de grãos, distribuição do sistema radicular e análise econômica para a soja e o milho. Em amostras de solo coletadas aos 9 e 24 meses após a implantação do experimento, nas camadas de 0 5, 5 10, 10-15, 15 20 e 20 30 cm foram determinados os teores trocáveis de Ca, Mg e Al, pH H2O, saturação por bases e saturação por Al, além dos teores de P disponível, K trocável e carbono orgânico. Todas as variáveis foram submetidas à análise da variância e quando significativas, as médias foram comparadas pelo teste de Tukey a 5 %. Os resultados mostram que acidez em subsuperfície (10-20 cm) não foi limitante à produtividade da soja e do milho quando a camada superficial (0-10 cm) estava em níveis recomendados pela CQFS-RS/SC (2004), o que não permitiu a definição do melhor modo de aplicação de calcário sob o ponto de vista de produtividade de grãos e viabilidade econômica, porém, a incorporação de calcário por lavração foi o modo mais eficiente de correção da acidez em subsuperfície.

O presente trabalho apresenta um estudo das condições geotécnicas e do monitoramento da obra de ampliação dos molhes, proteção da entrada do canal de navegação do Porto de Rio Grande-RS/ Brasil, assente em solos moles. Atenção é dada a problemas associados à capacidade de carga e recalque das fundações. Investigações indicaram que o solo de fundação é constituído de uma camada de areia com 3 a 5 m de espessura abaixo do piso marinho, seguida de camada de argila mole, com índice NSPT de 2 a 4 e espessura média de 15 m. Somente abaixo dessa profundidade ocorrem solos de maior resistência. Deste modo, antecipou-se no projeto que as camadas do subsolo marinho iriam sofrer recalques e deslocamentos significativos quando submetidas às cargas decorrentes do alteamento dos molhes, havendo a necessidade de garantir as condições de estabilidade a partir da construção de bermas de equilibrio. Devido aos riscos, a obra foi concebida como observacional, sendo acompanhada de instrumentação de controle do processo construtivo, incluindo a observação das poro-pressões, recalques e deslocamentos horizontais na camada de argila mole, compressível e de baixa resistência. A instrumentação implantada na obra inclui inclinômetros, medidores do tipo aranha e piezômetros, sendo tal instrumentação pioneira no Brasil em obras nearshore, pois devido às condições marítimas adversas, parte dos instrumentos envia os dados via rádio, com monitoramento contínuo em tempo real. Este trabalho apresenta relatos das etapas da obra, incluindo a investigação das condições do subsolo e a instalação da instrumentação, constituindo-se igualmente em um desafio devido à profundidade, às restrições de acesso, ventos, impacto de ondas e correntes. Os resultados da instrumentação foram analisados e sistemas de alerta foram implantados para garantir as condições de segurança durante todas as etapas construtivas dos molhes. / The present work presents the study of the geotechnical conditions and the monitoring of the breakwaters enlargement work in Rio Grande-RS/Brazil. The breakwaters are the protection for the Rio Grande harbor channel, based on soft soils. Focus is given to problems associated to the load and settlements of the foundations. Investigations have indicated that the soil is constituted of a 3 to 5 meter thick sand layer under the sea floor, followed by a soft clay layer with NSPT between 2 and 4 and 15 meter average thick. Only under this depth soils with larger strength occur. Therefore, it was predicted in the project that the layers from the sea subsoil would experience considerable settlements and displacements when they undergo the loads from the breakwaters heightening, existing the need to ensure stability conditions with the construction of balance berms. Due to risks, the work was conceived as observational and it has been accompanied by a control instrumentation of the constructive process, including pore water pressure observations as well as horizontal and vertical displacements in the clay layer. The implemented instrumentation includes inclinometers, spider magnet meters and piezometers. The use of these instrumentations has been considered pioneer in nearshore works in Brazil because, due to the adverse sea conditions, part of them send data by radio signal, with continuous monitoring on real time. This work presents reports from the steps taken in the work, including the investigation of the subsoil conditions and the installation of the instrumentation, which had constituted a challenge due to the depth, access restriction, wind, wave impact and the sea flow. Instrumentation results were analyzed and alert systems were deployed to ensure safety conditions during all the constructive steps of the breakwaters.

O presente trabalho apresenta um estudo das condições geotécnicas e do monitoramento da obra de ampliação dos molhes, proteção da entrada do canal de navegação do Porto de Rio Grande-RS/ Brasil, assente em solos moles. Atenção é dada a problemas associados à capacidade de carga e recalque das fundações. Investigações indicaram que o solo de fundação é constituído de uma camada de areia com 3 a 5 m de espessura abaixo do piso marinho, seguida de camada de argila mole, com índice NSPT de 2 a 4 e espessura média de 15 m. Somente abaixo dessa profundidade ocorrem solos de maior resistência. Deste modo, antecipou-se no projeto que as camadas do subsolo marinho iriam sofrer recalques e deslocamentos significativos quando submetidas às cargas decorrentes do alteamento dos molhes, havendo a necessidade de garantir as condições de estabilidade a partir da construção de bermas de equilibrio. Devido aos riscos, a obra foi concebida como observacional, sendo acompanhada de instrumentação de controle do processo construtivo, incluindo a observação das poro-pressões, recalques e deslocamentos horizontais na camada de argila mole, compressível e de baixa resistência. A instrumentação implantada na obra inclui inclinômetros, medidores do tipo aranha e piezômetros, sendo tal instrumentação pioneira no Brasil em obras nearshore, pois devido às condições marítimas adversas, parte dos instrumentos envia os dados via rádio, com monitoramento contínuo em tempo real. Este trabalho apresenta relatos das etapas da obra, incluindo a investigação das condições do subsolo e a instalação da instrumentação, constituindo-se igualmente em um desafio devido à profundidade, às restrições de acesso, ventos, impacto de ondas e correntes. Os resultados da instrumentação foram analisados e sistemas de alerta foram implantados para garantir as condições de segurança durante todas as etapas construtivas dos molhes. / The present work presents the study of the geotechnical conditions and the monitoring of the breakwaters enlargement work in Rio Grande-RS/Brazil. The breakwaters are the protection for the Rio Grande harbor channel, based on soft soils. Focus is given to problems associated to the load and settlements of the foundations. Investigations have indicated that the soil is constituted of a 3 to 5 meter thick sand layer under the sea floor, followed by a soft clay layer with NSPT between 2 and 4 and 15 meter average thick. Only under this depth soils with larger strength occur. Therefore, it was predicted in the project that the layers from the sea subsoil would experience considerable settlements and displacements when they undergo the loads from the breakwaters heightening, existing the need to ensure stability conditions with the construction of balance berms. Due to risks, the work was conceived as observational and it has been accompanied by a control instrumentation of the constructive process, including pore water pressure observations as well as horizontal and vertical displacements in the clay layer. The implemented instrumentation includes inclinometers, spider magnet meters and piezometers. The use of these instrumentations has been considered pioneer in nearshore works in Brazil because, due to the adverse sea conditions, part of them send data by radio signal, with continuous monitoring on real time. This work presents reports from the steps taken in the work, including the investigation of the subsoil conditions and the installation of the instrumentation, which had constituted a challenge due to the depth, access restriction, wind, wave impact and the sea flow. Instrumentation results were analyzed and alert systems were deployed to ensure safety conditions during all the constructive steps of the breakwaters.

Ce travail de thèse présente la conception et la réalisation d'une antenne Ultra Large Bande, de faibles dimensions, destinée à une application géoradar fonctionnant dans un milieu complexe pour une bande fréquentielle comprise entre 70 MHz et 1GHz. Cette étude était inscrite dans le cadre d’un projet Européen dénommé NeTTUN (New Technologies for Tunnelling and Underground works) qui a pour but d’améliorer la sécurité du creusement des tunnels. Dans ce projet, le travail demandé était de réaliser un système géoradar comportant une antenne ULB intégrable sur une tête de coupe d’un tunnelier tout en fonctionnant en basses fréquences.Pour réaliser cette antenne en répondant aux différentes contraintes à la fois de dimensions, d’intégration et de rayonnement, une étude d’insertion de l’antenne dans un matériau diélectrique a été effectuée. Ainsi des analyses ont été menées à fois sur la nature des sous-sols rencontrées, du compromis entre fréquences basses et dimensions minimales mais surtout de l’intégrabilité de l’antenne dans une cavité. Cette étude a permis de concevoir une antenne innovante nommé Khorn étant une association de l’antenne K et de la forme « Horn » d’une antenne cornet. Afin d’évaluer la performance de l’antenne Khorn dans son environnement, la tache de rayonnement et la portée de l’ensemble, antenne et source ont été analysées. Des mesures de validation des prototypes fabriquées ont aussi été effectuées. / This work presents the design and the realization of an antenna Ultra Wide Band, of low dimensions, for a GPR application working in a complex environment in a frequency band between 70 MHz and 1GHz. This study was registered within the framework of a European project mentioned NeTTUN (New Technologies for Tunnelling and Underground works) who aims at improving the security of the tunnel driving. In this project, the wanted work was to realize a GPR system containing an integrable antenna ULB on a TBM cutter head while working in low frequencies.To realize this antenna by answering the various constraints of dimensions, integration and radiation, a study of antenna insertion in a dielectric material was realized. So analyses were led for time on the subsoil nature encountered, of the compromise between low frequencies and minimal dimensions and especially the integrability of the antenna in a cavity. This study allowed to realize an innovative antenna named Khorn. The Khorn is an association of the K antenna and the Horn antenna. To estimate the performance of the Khorn in its environment, the footprint and the radar range were studied. Measures of validation of the realized prototypes were also made.

In the 1980s, the meadows around Senotín in southern Bohemia were drained by subsurface pipe drainage. After considerable drought in 1992, this area was subjected to extensive research. In 1995, a part of the drained area was revitalized. The drainage pipeline was interrupted by seven clay screens, over four of them country lanes and shallow depressions were built. The research of this site was realized after revitalization and focused on the water regime of the soil and on the physical, chemical and biological properties of the soil. This thesis describes the state of water regime, physical and chemical parameters of soil in undrained, drained and revitalized areas 20 years after revitalization and compares them with data from research performed in the past. The rainfall and runoff data was measured in the catchment area, and soil samples were collected in the regular network. Research has shown that between 1998 and 2014 there has been a reduction in river runoff. However, a more detailed data analysis has identified the vegetation transpiration as the main factor. There has been no increase in soil retention or soil moisture. None of the investigated soil parameters on the revitalized area (bulk density, carbon and nitrogen content, C:N ratio, pH, and conductivity of the aqueous extract) is...

Master’s thesis deals with the design and assessment of the bearing structure of sewage treatment plant and development of the drawnings. The thesis solves the main part of the structure: base slabs, walls and ceiling slabs. Thesis solves the ultimate limit state and ultimate limit serviceability.

Mikrobielle Hotspots zeichnen sich durch erhöhte mikrobielle Biomasse und Aktivität im Vergleich zum Gesamtboden aus. Sie umfassen nur einen sehr kleinen Teil des Bodenvolumens, indem jedoch die meisten für Stoffkreisläufe relevanten mikrobiellen biogeochemischen Prozesse ablaufen. In mikrobielle Hotspots sind Prozessraten erhöht, wie beispielsweise verkürzte Umsatzzeiten der organischen Substanz und eine erhöhte Nährstoffmobilisierung im Vergleich zum Gesamtboden. Eine verbesserte Verfügbarkeit von niedermolekularen organischen Substanzen im Vergleich zum Gesamtboden stimuliert das Wachstum und die Aktivität von Bodenmikroorganismen. Mikrobielle Hotspots entstehen in Bodenkompartimenten, die durch Rhizodeposition, den Eintrag von Wurzelstreu, den Eintrag von nährstoffreichem Material von der Bodenfauna und die Auswaschung von organischen Verbindungen aus dem Oberboden einen erhöhten Substrateintrag aufweisen. Im Boden stellen die Rhizosphäre sowie Bioporen wichtige mikrobielle Hotspots dar. Speziell im nährstoffarmen Unterboden sind mikrobielle Hotspots wichtig, da die Nährstoffe in den Hotspots im Vergleich zum Gesamtboden für Pflanzen besser verfügbar sind. Im Rahmen dieser Dissertation wurden 1) mikrobielle Hotspots anhand molekularer Proxies unterschieden; und 2) das Potential von Vorfrüchten mit Pfahlwurzelsystem zur Ausbildung und Aufrechterhaltung von mikrobiellen Hotspots im Unterboden untersucht; darüber hinaus wurde 3) die mikrobielle Umsetzung des wurzelbürtigen Kohlenstoffs entlag eines Teifengradienten bis in 105 cm Tiefe bestimmt; und 4) die räumliche Ausdehnung der mikrobiellen Hotspots im Ober- und Unterboden anhand der Verteilung und anhand des Umsatzes von wurzelbürtigem Kohlenstoff, sowie anhand von sich ausbildenden pH, Sauerstoff- und Redoxpotentialgradienten von der Wurzeloberfläche in den Gesamtboden bestimmt. Im Rahmen eines Feldexperimentes wurde Luzerne (Medicago sativa L.) zwei Jahre lang auf einem Haplic Luvisol angebaut. Drilsophäre, Rhizosphäre und der Gesamtboden wurden in 15 cm Intervallen bis in eine Tiefe von 105 cm beprobt, um mikrobielle Hotspots anhand von molekularen Proxies zur unterscheiden. Die Proben wurden auf ihre Gehalte an freien extrahierbaren Fettsäuren untersucht. Dafür wurden aus dem Gesamtlipidextrakt die Fettsäuren durch Festphasenextraktion abgetrennt. Die Differenzierung des organischen Materials aus der Drilosphäre, der Rhizosphäre und dem Gesamtboden wurde mittels einer linearen Diskriminanzanalyse durchgeführt. Desweiteren wurde auf der Versuchsfläche neben Luzerne auch Wegwarte (Cichorium intybus L.) angebaut. Um den Kohlenstoffeintrag von Luzerne und Wegwarte in den Boden entlag eines Tiefengradientens zu vergleichen, wurden je drei Luzerne und drei Wegwarteparzellen nach 110 Tage Wachstum in situ mittels 13CO2 pulsmarkiert. Die Verteilung des assimilierten 13C in Spross, Wurzeln und Bodenkohlenstoffpools sowie die Bestimmungen der jeweiligen Kohlenstoffpoolgrößen ermöglichte es, den Kohlenstoffeintrag bis in eine Bodentiefe von 105 cm zu quantifizieren. In einer Laborstudie wurde die räumliche Ausdehnung mikrobieller Hotspots untersucht. Zu diesem Zweck wurde Luzerne in T-förmigen Gefäßen mit drei Kompartimenten zwei Monate lang kultiviert. Die Gefäße waren entweder mit Ober- oder Unterboden gefüllt. Die Wurzeln konnten nur im mittleren Teil der Gefäße wachsen, da eine Nylongaze sie daran hinderte in die seitlichen Rhizosphärenkompartimente vorzudringen. Unterschiedliche Maschenweiten der Gaze verhinderten entweder nur das Wurzelwachstum oder sowohl das Wurzelwachstum als auch das Eindringen der Hyphen von arbuskulären Mykorrhizapilzen in die Rhizosphärenkompartimente. Die Dynamik und Verteilung von wurzelbürtigem Kohlenstoff in der Rhizosphäre, wurde durch die Markierung der Luzerne mit 14CO2 und anschließende Messung der 14C-Aktivität im gelösten organischen Kohlenstoff und im gesamten organischen Kohlenstoff ermittelt. Um Unterschiede im mikrobiellen Abbau der abgegebenen Substanzen in der Ober- und Unterbodenrhizosphäre zu bestimmen, wurden die Aktivitäten extrazellulärer Enzyme gemessen. Zur Messung von Sauerstoff- und Redoxpotentialgradienten bei unterschiedlichem Matrixpotenzial in der Ober- und Unterbodenrhizosphäre wurden ein Sauerstoffmikrosensor und Platinelektroden verwendet. Während die relativen Gehalte an ungesättigten Fettsäuren von Drilosphäre, über Rhizosphäre bis zum Gesamtboden abnahmen, verhielten sich die Dicarbonfettsäuren genau umgekehrt. Da diese Unterschiede unabhängig von der Bodentiefe waren, konnten diese Proxies zur Unterscheidung der Herkunft des organischen Materials verwendet werden. Mittels einer linearen Diskriminanzanalyse konnte so das organsiche Material mikrobieller Hotspots von dem des Gesamtbodens durch eine lineare Kombination der relativen Gehalte an ungesättigten Fettsäuren und Dicarbonsäuren unterschieden werden. Die unterschiedlichen Quellen des organischen Materials und dessen intensive mikrobielle Überformung veranschaulichen die Komplexität der Prozessse, die zur Entstehung von mikrobiellen Hotspots beitragen. Um diese Prozesse zu untersuchen, wurde das Potential von Vorfrüchten mit Pfahlwurzelsystem zur Ausbildung und Aufrechterhaltung mikrobieller Hotspots im Unterboden analysiert. Dafür wurde der Kohlenstoffeintrag über die Wurzelbiomasse und durch Rhizodeposition sowie die mikrobielle Aufnahme bis in eine Tiefe von 105 cm quantifiziert. Die Ergebnisse zeigten, dass die Ausbildung mikrobieller Hotspots im Unterboden während der ersten Vegetationsperiode durch Luzerne stärker ist als durch Wegwarte. Die Gründe hierfür waren: 1) Ein höherer Biomassezuwachs von Luzerne und 2) eine 8 fach höherere Verlagerung des assimilierten Kohlenstoffs in das Wurzelwachstum sowie in Rhizodeposite im Unterboden durch Luzerne. Unter Luzerne wurde durch den erhöhten Eintrag von leichtverfügbarem Kohlenstoff das mikrobielle Wachstum und der Umsatz an mikrobiellem C im Unterboden erhöht. Dies weist auf höhere Nährstoffumsatzraten und damit auf deren höhere Pflanzenverfügbarkeit hin. Das könnte zu einer verbesserten Nährstoffversorgung der Hauptfrüchte beitragen, wenn deren Wurzeln durch die ehemaligen Luzernewurzelporen im Unterboden wachsen. Im Gegensatz zur Luzerne bildete die Wegwarte den größten Teil ihrer Wurzelbiomasse im Oberboden aus wohin sie auch den größten Teil ihrer Rhizodeposite exsudierte. Aus diesem Grund ist die Wegwarte zumindest in der ersten Vegetationsperiode nicht als Vorfrucht zu empfehlen, um die Nährstoffverfügbarkeit im Unterboden zu verbessern. Um die Relevanz von mikrobiellen Hotspots für Nährstoffkreisläufe besser zu verstehen, ist es notwendig die Ausdehnung des Bodenvolumens mit erhöhten Prozessraten und die Gradienten mit denen diese Prozessraten zum Gesamtboden hin abnehmen zu untersuchen. Dies ermöglichte das oben beschriebene Experiment, bei dem Luzerne in den kompartimentierten Wachstumsgefäßen angezogen wurde. Hierbei zeigte sich, dass die Wurzelexsudation in die Oberbodenrhizosphäre verglichen mit der Exsudation in die Unterbodenrhizosphäre deutlich höher war. Allerdings waren die Gradienten der 14C markierten Wurzelexsudate im gelösten organischen Kohlenstoff von der Wurzeloberfläche in Richtung Gesamtboden steiler als im Unterboden. Da zusätzlich zu dem erhöhten Eintrag und den steileren Gradienten auch die Enzymaktivitäten im Oberboden höher waren, kann von einem erhöhtem mikrobiellem Abbau der Wurzelexsudate im Vergleich zur Unterbodenrhizosphäre ausgegeangen werden. Obwohl erwartet wurde, dass erhöhter mikrobieller Abbau zu einer geringeren diffusiven Ausdehnung der Wurzelexsudate in der Oberbodenrhizosphäre führen würde, war dies nicht der Fall. Sowohl in der Oberboden- als auch in der Unterbodenrhizosphäre wurde 14C aus Exsudaten bis in eine Entfernung von 28 mm im DOC und 20 mm im TOC zur Wurzeloberfläche nachgewiesen. Die Sauerstoffkonzentration nahm in Richtung zur Wurzeloberfläche ab, wobei der Gradient in Ober- und Unterbodenrhizosphäre identisch war. Ein Rhizosphäreneffekt auf die Sauerstoffkonzentration konnte bis in 20 mm Entfernung zur Wurzeloberfläche gemessen werden. Das Matrixpotenzial war ausschlaggebend für die diffusive Nachlieferung von Sauerstoff, und damit für die Aufrechterhaltung der aeroben Respiration in der Rhizosphäre. Bei einem Matrixpotenzial von -200 hPa oder weniger fand keine Hemmung der Respirationsprozesse durch mangelnde O2 Nachlieferung zur Wurzeloberfläche statt. Die auf der Sauerstoffkonzentration beruhenden Veränderungen des Redoxpotentials konnten bis in eine Entfernung von 2 mm zur Wurzeloberfläche erfasst werden. Nur unter ständiger Wassersättigung wurden in der Rhizosphäre schwach reduzierende Bedingungen erreicht. Im Rahmen dieses Dissertation konnte gezeigt werden, dass mikrobielle Hotspots im Boden eine größere laterale Ausdehnung erreichen als bislang angenommen. Darüber hinaus konnte gezeigt werden, dass diese Hotspots eine Schlüsselfunktion bei der Erhöhung von Kohlenstoff- und Nährstoffumsätzen besitzen. Daher empfiehlt sich der Anbau von tiefwurzelnden Vorfrüchten mit ausgeprägter C-Verlagerung in den Unterboden, wie beispielsweise Luzerne, um die Nährstoffverfügbarkeit aus dem Unterboden in Agrarökosystemen zu verbessern.

Made available in DSpace on 2017-07-25T19:29:55Z (GMT). No. of bitstreams: 1 Renato Zardo Filho.pdf: 15832288 bytes, checksum: e334707a14d42a6e9b7f1e5f0574d2ac (MD5) Previous issue date: 2012-11-10 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A considerably part of the high nitrogen (N) rates applied in corn is not absorbed due root growth restriction by subsoil acidity. Gypsum is able to improve conditions for root growth and lead to greater N uptake efficiency, increasing corn yield. Thus to evaluate the effect of gypsum and N on top dressing on soil chemical attributes, root growth , mineral nutrition and corn development under no-tillage system, two experiments were carried out on a dystrophic clayey Typic Hapludox at Middle-South of Paraná State, being one field and another in undisturbed soil columns. In the field experiment, four rates of gypsum (0, 5, 10 and 15 t ha-1) and three rates of N-NH4NO3 (60, 120 and 180 kg ha-1) were set up into 4 × 3 factorial design with three replications. On soil columns, two gypsum rates (0 and 10 t ha-1) and two rates of N-NH4NO3 (0 and 180 kg ha-1) were used in a 2 × 2 factorial design with five replicates. In both experiments, gypsum was applied on the surface, one week before sowing and 45 kg N ha-1 was applied at sowing. Were analyzed the changes in chemical soil properties, root development, nutrient uptake by corn in both experiments. On the field experiment were quantified the yield and efficiency in N use, and on the columns experiment the amount of N-NO3 - leaching was determined 45 days after the application of gypsum when the plants were cut off. On field experiment, gypsum increased levels of Ca2+, S-SO4 2- and P also decreased the exchangeable Al3+ level on subsoil layers. N rates raised up N-NO3 - levels throughout the soil profile and Ca2+ in 0,4-0,6 m. The increase in Ca2+ and S-SO4 2 levels on soil profile, as well the decrease on Al3+ saturation by gypsum application, improved plant root growth, and increased N, P, K, Ca, S, Zn and Mn extraction by maize, leading in increased corn grain yield. On top of that, gypsum rates improved N use efficiency by corn. In the soil columns experiment, gypsum and N application improved the plants roots to higher depths, which results in better plants dry matter and greater N, P, K, Ca, Mg, and S extraction. The amount of N-NO3 - leached on soil columns was higher when N was applied without gypsum. Gypsum application increased N uptake by plants due the root system increase and also increased of S-SO4 2-supply in soil, thus reducing the amount of N-NO3 - in the soil and leached. This results showed that gypsum use reduce losses of N-NO3 - leached by increasing N plants uptake, having as a result better N use efficiency contributing to higher corn yield sustainability. / Grande parte do nitrogênio (N) aplicado na cultura do milho não é absorvido devido à restrição no desenvolvimento do sistema radicular decorrente da acidez no subsolo. O gesso agrícola, por ter capacidade de melhorar o ambiente para o crescimento das raízes, pode aumentar a eficiência da absorção de N pelas plantas e a produtividade de grãos de milho. Com o objetivo de avaliar os efeitos da aplicação de gesso e de N em cobertura nos atributos químicos do solo, no crescimento de raízes, na nutrição mineral e na performance do milho cultivado em sistema plantio direto, foram realizados dois experimentos, sendo um no campo e outro em colunas indeformadas de solo, em um Latossolo Vermelho distrófico textura argilosa da região Centro-Sul do Paraná. No experimento de campo, quatro doses de gesso (0, 5, 10 e 15 t ha-1) e três de N-NH4NO3 em cobertura (60, 120 e 180 kg ha-1) foram combinadas em esquema fatorial 4 × 3, com três repetições. No experimento em colunas de solo, foram utilizadas duas doses de gesso (0 e 10 t ha-1) e duas doses de N-NH4NO3 (0 e 180 kg ha-1), em esquema fatorial 2 × 2, com cinco repetições. Nos dois experimentos, o gesso foi aplicado em superfície, uma semana antes da semeadura, e foram empregados 45 kg ha-1 de N na semeadura. Nos dois experimentos foram avaliadas as alterações nos atributos químicos do solo, no crescimento radicular e na absorção de nutrientes pelas plantas. A produtividade de grãos e a eficiência no uso do N foram avaliadas no experimento de campo, e a quantidade de N-NO3 - lixiviada aos 45 dias após a aplicação de gesso, no momento do corte das plantas, foi avaliada no experimento em colunas de solo. No campo, a aplicação de gesso elevou os teores de Ca2+, S-SO4 2- e P no solo, e reduziu a saturação por Al3+ nas camadas do subsolo. As doses de N em cobertura aumentaram o teor de N-NO3 - ao longo do perfil do solo e o teor de Ca2+ na camada de 0,4-0,6 m. O aumento na disponibilidade de Ca2+ e de S-SO4 2- no perfil do solo, bem como a redução na saturação por Al3+ no subsolo, com a adição de gesso, favoreceram o crescimento radicular do milho, a extração de N, P, K, Ca, S, Zn e Mn pelas plantas e a produtividade de grãos. Além disso, as doses de gesso melhoraram a eficiência no uso do N pelo milho. No estudo em colunas de solo, a aplicação de gesso e de N melhoraram o crescimento das raízes em profundidade. O maior crescimento radicular resultou em maior produção de matéria seca da parte aérea e maior extração de N, P, K, Ca, Mg e S pelas plantas. A quantidade de N-NO3 - lixiviada nas colunas de solo foi maior com a aplicação de N na ausência de gesso. A aplicação de gesso aumentou a absorção de N pelas plantas,proveniente da adubação nitrogenada, em decorrência de aumento no crescimento radicular e no teor de S-SO4 2- disponível no solo, reduzindo, com isso, a quantidade de N-NO3 - lixiviada. Os resultados mostraram que o uso de gesso minimiza as perdas de N-NO3 - por lixiviação por aumentar a absorção de N pelas plantas, ocasionando melhoria na eficiência da adubação nitrogenada e contribuindo para o aumento da sustentabilidade da produção de milho.