The aim of this thesis is to improve the control of urea injection at the combined power and heating plant Framtidens Gärstad (FTG). Tekniska Verken i Linköping AB is the owner of the plant. The FTG plant consists of a boiler where garbage combustion is done. From the combustion nitrogen oxides are emitted. These nitrogen oxides are hazardous to the environment. To reduce the nitrogen oxides, injection of urea into the boiler is used. Urea is an organic compound of carbon, nitrogen, oxygen and hydrogen. When urea reacts with nitrogen oxides they transform into harmless nitrogen gas and water. In the plant the urea is injected by six lances. The control of the urea injection at FTG could be improved which would save some money for the company. This is the main reason for the aim of this thesis. It is the control of the total flow of urea to the lances that is studied in this work. Some literature about reduction of nitrogen oxides is studied, especially reduction using urea injection. There are a lot of factors that affect how good the reduction becomes. The most important factors are the amount of urea being used and the temperature of the flue gases where the reaction with urea takes place. A model with these two factors as inputs and the content of nitrogen oxides as output is derived. This is done with experiments in the boiler and system identification. The system is modelled as a linear system. The proposal about the improved control uses the temperature from a temperature measurement just below the urea injection in the boiler. This is a parameter that the existing control does not use. The temperature is divided into three intervals. For each interval different parameters for the function of the system and the nitrogen oxide controller are used. The nitrogen oxide controller in the proposed control is derived with help from a new method of controldesign called AMIGO. The identification models gave good results in two of the temperature intervals. The result for the third interval was not so good. This is probably due to lack of good data. The proposed control structure could for practical reasons not be tested online but preliminary tests using measurement data gave qualitatively reasonable results. In order to improve the results temperature dependence has to be treated more systematically.

La fertilité des vaches laitières s’est beaucoup dégradée au cours des dernières décennies, tant à l’échelle nationale qu’internationale. L’objectif poursuivi est d’apporter un éclairage épidémiologique sur les relations dynamiques entre la conception (réussite à l’insémination artificielle ; IA), les mammites subcliniques et les déséquilibres métabolico-nutritionnels que sont la cétose subclinique et les déséquilibres azotés de la ration. Un premier chapitre bibliographique dresse l’état de l’art des liens entre performances de reproduction et (i) mammites, (ii) cétose subclinique et (iii) excès de protéines dégradables, en identifiant clairement les interactions et associations croisées entre ces différents composants, et en quantifiant autant que possible ces liens. Les trois parties suivantes mobilisent des données exhaustives du contrôle laitier français sur la période 2008-2012, qui ont été confrontées aux données d’IA. La variable d’intérêt retenue est la conception après IA, soit pour la première IA (IA1) ou pour toutes les IA. Les variations des concentrations de cellules somatiques (CCS) autour de l’IA ont été utilisées pour décrire la dynamique des mammites subcliniques autour de l’IA, selon 4 classes (Bas-Bas, Bas-Haut, Haut-Bas et Haut-Haut) et pour différents seuils de CCS. Le statut de cétose subclinique a été évalué grâce aux taux butyreux et protéique du lait. Les concentrations d’urée du lait sont utilisées pour caractériser les déséquilibres azotés. Le second chapitre propose une description succincte des résultats de production et de reproduction des troupeaux bovins laitiers français sur la période d’étude. Le troisième chapitre focalise sur l’interaction entre les CCS et la cétose subclinique dans un modèle de régression de Poisson expliquant la conception. Les chances de conception à l’IA1 sont réduites de 14% (Risque relatif = 0,86 [IC 95%=0,85–0,87]) pour les groupes Bas-Haut et Haut-Haut, comparé au groupe Bas-Bas, et de 3 à 17 %, selon les définitions retenues, lors de cétose subclinique comparé à son absence. Les résultats identifient et quantifient clairement l’interaction entre la cétose subclinique et les mammites subcliniques dans leur association avec la conception : la baisse de la conception est jusqu’à 2 fois supérieure lors de la présence simultanée d’une augmentation des CCS et d’une cétose subclinique par rapport à la situation où il y a seulement augmentation des CCS. Le quatrième chapitre, mobilisant des méthodes proches de celles du chapitre précédent, montre que la baisse de la concentration d’urée dans le lait autour de l’IA (en dessous de 150 mg/kg, 2,6 mmol/L) est associée à une baisse de la conception de 5 à 9% (Risque relatif = 0.91 (IC95%=0,87-0,96)]) par rapport à des concentrations d’urée du lait qui restent stables (250 - 450 mg/kg ou 4,3-7,7 mmol/L). Ceci révèle l’importance de la stabilité du métabolisme azoté autour de la conception, y compris pour des variations d’urée du lait ou du sang à la baisse, alors que seule la hausse de la concentration d’urée était identifiée comme un facteur de risque de dégradation des résultats de reproduction jusqu’alors. La dernière partie permet de mettre en perspective ces éléments originaux. Une des principales limites de ces travaux est la définition imprécise de la cétose subclinique réalisée à partir des taux du lait ; les résultats actuels bénéficieraient d’une actualisation avec un indicateur plus précis de ce trouble. Ces résultats soutiennent qu’une inflammation locale peut affecter la réponse de l’ensemble de l’organisme et altérer les fonctions d'autres organes dans les semaines qui suivent son apparition. Ils illustrent la complexité et les interactions entre les différents troubles chez un même animal. Par ailleurs, maintenir des concentrations basses de l’urée est légèrement pénalisant pour la conception, et ne garantit pas de meilleurs résultats de reproduction. / Reproductive performances of dairy cows are recognized as a key parameter for the profitability of dairy farms, but they are getting worse continuously in many countries during the last decades. Infectious and nutritional disorders are possible contributors to these changes. Mammary infection, nitrogen imbalance and metabolic disorders have been reported to be negatively associated with conception, but their interactions and dynamics are not fully understood. The objective of the present work is to better describe the relationship between fertility, udder health, subclinical ketosis (SCK) and nitrogen imbalance accounting for the temporal variations of these events and their interactions. The first section reviews the link between reproductive performances and (i) mastitis, (ii) metabolic disorders and (iii) nitrogen imbalance in dairy cows in order to clarify the complex interaction among these events. The three other sections are based on exhaustive data from the national French dairy milk improvement system and data on the artificial inseminations (AI) from 2008 to 2012. Fertility was explained as conception at the first (AI1) or at all AI. The udder health status was evaluated through the somatic cells counts (SCC). Several proxies based on the milk fat and protein contents were proposed to define SCK. Milk urea concentration was used to investigate the exposure to nitrogen imbalance. The second section aims to describe the actual situation of milk production and reproduction in French dairy herds. The third section focuses on the interaction between SCC and SCK and their association with conception. On average, the risk of conception at AI1 was 14% lower when the SCC increased or remained high within 40 days before and after AI (Relative risk [and 95% CI] = 0.86 [0.85–0.87]), compared to low SCC before and after AI. The reduction in conception rate associated with SCK (fat and protein contents changes) varied from 3% to 17% depending on the SCK proxy used. Including the interaction term SCC*SCK clearly showed that the association of increased SCC around AI with conception was modified by the presence of SCK. A cow that already has SCK and experiences an increase in SCC around or after AI exhibits up to 2 times further decrease in conception, compared with a cow with a high SCC and no SCK. The fourth section, using similar methods as the previous one, shows that low milk urea concentrations after AI are negatively associated with conception. Cows with a low urea (< 150 mg/kg, 2.6 mM) after AI have a reduced conception (Relative risk RR [and 95% CI] = 0.96 [0.94–0.99]) compared to cows with intermediate urea (250-450 mg/kg, 4.3 - 7.7 mM) after AI. Furthermore, the risk of conception was 5 to 9% lower (relative risk [and 95% CI] = 0.91 [0.87–0.96]) when urea concentrations decrease from intermediate before to low after AI, compared with cows with constant intermediate urea values. This work revealed that a decrease in urea from intermediate (before AI) to low (after AI) is a risk factor for conception failure in addition to the previously known risk factor that is nitrogen excess. The final section aims to highlight the perspectives of these results. The definition of SCK used in this work was identified as the main limitation and the present results would benefit from an update with a better indicator of this disorder. The present work supports that a local inflammation may affect the entire body response and alters the functions of other organs like those of the reproductive tract. Furthermore, maintaining low urea concentrations does not provide any particular advantage and might be negatively associated with conception.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / An in vivo digestibility experiment was conducted to evaluate the influence of degradable nitrogen source and feeding frequency on the digestion process and utilization of kikuio grass hay. Eight castrated male lamb (35 ± 4 Kg live weight) maintained in individual metabolic cage, were used in a 2x2 factorial experiment according to a replicated 4x4 Latin Square design. Treatments tested were the combination of two supplement feeding frequencies: once (morning) or twice (morning and aftermoon) daily, and two supplements, based on cassava meal plus calcium caseinate or cassava meal plus urea. For all treatments kikuio hay was fed ad. Libitum and the supplements were fed at a rate of 7 g/Kg live weight daily. Animals supplemented twice day consumed higher quantity of the gross fractions, either in absolute values or in proportion to live weight or metabolic weight (P<0,05) and they tended to consume higher quantity of digestible energy and to synthesize more microbial protein (P<0,10). Feeding frequency did not influence the digestibility. When calcium caseinate was fed animal tended (P<0,10) to have higher dry matter intake in relation to live weight and higher organic matter intake in relation to metabolic weight. There was interaction between nitrogen source × frequency of supplementation on intake of both digestible organic matter and digestible energy. Animals receiving supplement with calcium caseinate twice a day and supplemented with urea once a day have higher intake of theses fractions. Animals supplemented once a day presented higher rumen sugar concentration (P<0,05), but pH as well as ammonia and peptides + aminoacid concentration were not affected by supplementation frequencys. Higher concentrations of NH3 and lower concentrations of pep+aa were observed in animals supplemented with urea (P<0,05). The supplement feeding frequency did not influence the digestion process and forage utilization when the nitrogen source was urea, but when the nitrogen source was calcium caseinate, supplementation twice daily improves intake and nutrients offer to the animals. / Para avaliar se as freqüências de oferta de suplemento, com diferentes tipos de nitrogênio degradável, influenciam os processos de digestão e a utilização do feno de uma gramínea tropical, foi realizado um estudo de digestibilidade in vivo, utilizando oito ovinos machos castrados (PV médio 35 ± 4 Kg), mantidos em gaiolas de metabolismo individuais em um delineamento duplo quadrado latino 4x4 em um esquema fatorial 2x2. Como volumoso foi utilizado feno de capim quicuio (Pennisetum clandestinum) com 70 dias de rebrota, como suplemento foi utilizada uma mistura a base de farinha de mandioca mais uréia ou caseinato de cálcio, além de uma mistura de sal mineral comercial e melaço em pó. Os tratamentos foram duas freqüências de suplementação × duas fontes de nitrogênio. As combinações foram suplementação com farinha de mandioca mais caseinato fornecido uma vez ao dia (manhã) e duas vezes ao dia (manhã e tarde) e suplementação com farinha de mandioca mais uréia uma vez ao dia (manhã) e duas vezes ao dia (manhã e tarde) à nível de 7 g/Kg de PV. O volumoso foi fornecido Ad. Libitum duas vezes ao dia (manhã e tarde). Os animais quando suplementados duas vezes ao dia consumiram maior quantidade das frações brutas, tanto em valores absolutos, como em proporção ao PV ou peso metabólico (P<0,05) e tenderam a consumir maior quantidade de energia digestível e a sintetizar mais proteína microbiana (P<0,10). A freqüência de suplementação não influenciou na digestibilidade e a eficiência da síntese de proteína microbiana. Somente houve uma tendência de quando os animais foram suplementados com caseinato consumirem maior quantidade de matéria seca em relação ao peso vivo e matéria orgânica em g/Kg de peso metabólico (P<0,10), não havendo mais nenhum efeito da suplementação com diferentes fontes de nitrogênio degradável no rúmen. Houve interação fonte de nitrogênio × freqüência de suplementação no consumo de matéria orgânica digestível e energia digestível onde os animais quando recebendo suplemento com caseinato duas vezes ao dia e quando suplementados com uréia uma vez ao dia consumiram mais destas frações. Quando os animais foram suplementados uma vez por dia apresentaram maiores concentrações ruminais de açucares (CHO) (P<0,05), e o pH, amônia (NH3) e peptídeos + aminoácidos (pep+aa) não foram influenciados pelas diferentes freqüências de suplementação. Maiores concentrações ruminais de NH3 e menores de pep+aa foram observadas quando os animais foram suplementados com uréia (P<0,05). A suplementação com farinha de mandioca mais caseinato fornecido duas vezes ao dia manifestou ser superior as demais suplementações, no entanto os mecanismos não ficaram bem estabelecidos, necessitando estudos adicionais.

This thesis was developed with the objective of evaluating the effect of supplementation with 10% crude glycerin in the total dry matter (DM) of the diet for lactating cattle in a annual ryegrass (Lolium multiflorum) pasture production system on the metabolic profile, milk composition and production. The experiment was conducted at the Regional Rural Development Institute in Augusto Pestana, RS, Brazil, with 18 Holstein cattle, in a block design (according to lactation days) in a simple cross-over procedure, during three periods of 14 days. The diets were composed of annual ryegrass grazing and supplementation with corn silage and concentrate, with or without addition of 10% crude glycerin based on total dry matter. Samples of diet, urine, milk and blood were collected and evaluated. It were evaluated too milk production and leftover food in the trough. The data were submitted to analysis of variance and the treatment effect compared by the T test through the SAS statistical program. Values of P<0.05 were considered significant and tendency were considered when P<0.10. It was verified that the inclusion of 10% of crude glycerin in diet DM of lactating cows reduces the elimination of urea through milk and increases blood glucose levels, and does not have a deleterious effect on milk production and cows’ feed consumption. The addition of 10% DM of glycerin to the diet hasn’t effect on milk production and composition of Holstein cows in different lactation periods with different levels of protein in the diet. It was concluded that the inclusion of 10% crude glycerin in diet DM of lactating cows on annual ryegrass pasture reduces the level of milk nitrogen urea. This could be due to the decrease in urea blood levels by the increase of nutritional efficiency, provided by glycerin energy supply, for its energy and potential contribution in increasing blood glucose levels, without interfering in the productive performance and composition of the milk. / Esta tese foi desenvolvida com o objetivo de avaliar o efeito da suplementação com 10% de glicerina bruta na matéria seca (MS) total da dieta, para vacas em lactação, mantidas em sistema de produção em pastagem de azevém (Lolium multiflorum), sobre o perfil metabólico, composição e produção do leite. O experimento foi conduzido no Instituto Regional de Desenvolvimento Rural, em Augusto Pestana, RS, Brasil, com 18 vacas da raça holandesa, em um delineamento com blocos (conforme o perfil da lactação) em esquema de reversão simples dos animais (Cross-over), em três períodos de 14 dias. As dietas foram constituídas de pastejo em azevém e suplementação com silagem de milho e concentrado, acrescido ou não da adição de 10% de glicerina bruta com base na matéria seca (MS) total. Foram coletadas e analisadas amostras de alimentos, urina, leite e sangue. Foram avaliadas também sobras de alimento no cocho e produção de leite. Os dados foram submetidos à análise de variância e o efeito de tratamento comparado pelo teste T através do programa estatístico SAS. Valores de P<0.05 foram considerados significativos e como tendência quando P<0.10. Verificou-se que a inclusão de 10% de glicerina bruta na MS da dieta reduz à eliminação de ureia via leite e aumenta os níveis sanguíneos de glicose, não tendo efeito deletério sobre a produção de leite e consumo de alimento dos animais. A adição de 10% da MS de glicerina a dieta não apresenta efeito sobre a produção e composição do leite de vacas da raça holandesa, em diferentes períodos de lactação. Conclui-se que a inclusão de 10% de glicerina bruta na MS da dieta de vacas em lactação, em pastejo de azevém, diminui o nível de nitrogênio ureico no leite em função da melhora da eficiência nutricional, pelo seu aporte energético e potencial em aumentar os níveis de glicose sanguínea, sem interferir no desempenho produtivo e na composição do leite.

Please read the abstract in the dissertation. / Dissertation (MSc)--University of Pretoria, 2009. / Chemical Engineering / unrestricted

Conventional urea-based moulding compounds for investment casting patterns are manufactured using a slow “cooking” process. Nowadays in industrial processes the use of a faster process is highly recommended to increase throughput levels. At the same time, for quality control purposes, the requirements of an investment caster must be met. This study is therefore focused on: <ul><li> Finding the appropriate conventional process and conditions to prepare urea-based investment casting moulding compounds. </li><li> Optimising the composition variables to meet the mechanical, thermal, surface, flow and cost properties needed in investment casting. </li><li> Characterising the moulding compounds to meet the requirements of an investment caster by comparing them with an industrial, “cooked” urea-based compound. </li></ul> Polyvinyl alcohol (PVOH) and ethylene vinyl acetate (EVA) urea-based moulding compounds were prepared using a two-roll mill and a conventional extrusion processes respectively. It was possible to injection mould PVOH urea-based moulding compounds with a urea content of up to 90 wt % which had been compounded using a two-roll mill. Using the conventional extrusion process, it was also possible to compound and injection mould EVA urea-based moulding compounds containing up to 70 wt % urea. The effects on composition variables on the properties of the moulding compound were studied and compared to those of the existing “cooked” urea-based moulding compound (Benchmark). The mechanical properties were characterised using the three-point bending test and Charpy impact test. The thermal properties were determined using simultaneous differential thermal analysis and thermogravimetric analysis (SDTA/TGA) and differential scanning calorimeter (DSC). The thermo-mechanical and visco-elastic properties were determined using a dynamic mechanical analyser. A scanning electron microscope was used to study the surface texture of the mouldings. The EVA urea-based moulding compounds showed two endothermic melting peaks and multiple exothermic crystallisation peaks in the DSC curves. The peak at ca. 55 - 66°C corresponds to the melting of the wax/EVA blend, while the large peak at 130 - 132°C corresponds to the melting of the urea. The DSC heating curve of the PVOH urea-based moulding compounds showed two endothermic peaks. The small peak corresponds to the melting of the wax, while the large peak corresponds to the melting of the urea/PVOH blend. PVOH urea-based moulding compound had better mechanical properties than the industrial benchmark. The mechanical properties of the EVA urea-based compound were generally lower. The effect of the wax and polymer content on the mechanical properties was as follows: <ul><li> Increasing polymer content produced weaker but tougher moulding compounds. </li><li> Increasing wax content improved the strength and stiffness but gave compounds that were less tough. </li><li> Two-way Analysis of Variance (ANOVA) indicated significant polymer-wax interactions. </li></ul> The urea content determined the stiffness (elastic modulus) of the compounds. PVOH mouldings had superior stiffness compared with the EVA and cooked urea-based mouldings. The Dynamic mechanical analysis (DMA) results confirmed the result obtained from the modulus of elasticity determination in the three-point bending test. The impact strength increased with an increase in polymer content and reduced with an increase in wax content. The linear thermal expansion coefficient decreased as the urea content was increased. Measured values (100 to 156x10-6°C) were comparable to those of the benchmark. The cooked urea-based moulding compound had the lowest melt viscosity at 110°C, as indicated by its melt flow index (MFI). Fluidity increased with the polymer content. The thermo gravimetric analysis (TGA) results confirmed that both the PVOH and EVA urea-based moulding compounds decomposed readily and left less than 1 wt % ash after combustion. From the SEM results apparent surface roughness appeared to increase with wax content. The EVA urea-based moulding compound had an irregular surface texture. Based on the criteria of cost-effectiveness and environmental friendliness, the synthesis of PVOH urea-based patterns is preferable. The use of a conventional extrusion process to prepare PVOH urea-based patterns is recommended. / Thesis (PhD)--University of Pretoria, 2011. / Chemical Engineering / unrestricted

A urease vem sendo cada vez mais caracterizada como uma enzima muito importante na hidrólise da uréia, fornecendo nitrogênio para a planta. Estudos anteriores realizados no Laboratório de Fisiologia Vegetal do IBUSP demonstraram a preferência da bromélia Vriesea gigantea pela absorção de uréia e a localização da urease nas membranas e citoplasma. Evidências recentes apontam também para uma possível utilização do carbono a partir da uréia, possivelmente explicando a grande afinidade que esta bromélia tem por esse composto nitrogenado. Essa capacidade da uréia fornecer também carbono à planta poderia desempenhar uma estratégia importante sob condições que limitam a entrada de CO2 atmosférico pelos estômatos, como no caso da deficiência hídrica. Atualmente conhece-se muito pouco sobre o ciclo diurno da atividade da urease nas plantas e particularmente em folhas de Vriesea gigantea sob limitação de água. Imagina-se que numa condição de escassez d\'água e, portanto, aumento do fechamento estomático, a uréia seria muito importante, tanto como fonte de nitrogênio (N) quanto de carbono. Isso acarretaria possivelmente numa preferência ainda maior por essa fonte orgânica de N na natureza. Folhas destacadas de Vriesea gigantea foram submetidas ao déficit hídrico por polietilenoglicol (PEG) 6000 por 8 dias, para garantir a limitação da entrada de CO2 por meio do fechamento estomático. Ao mesmo tempo, foram feitas análises nas diferentes porções foliares (ápice, mediana e base) do teor relativo de água, de ácidos orgânicos e das atividades das enzimas fosfoenolpiruvato carboxilase (PEPC) e malato desidrogenase (MDH), visando caracterizar se houve aumento da expressão do CAM durante o estabelecimento do déficit hídrico. Também foi fornecida uréia dissolvida na solução de PEG como fonte nitrogenada, e o ciclo de atividade da urease foi comparado aos resultados obtidos onde as folhas estiveram numa condição hídrica favorável (uréia dissolvida em água). Foi feita também a localização intracelular do CO2 (gerado pela atividade dessa enzima) por meio de reação específica de precipitação do CO2, cuja visualização foi realizada em microscópio eletrônico de transmissão. Após 8 dias de escassez hídrica, o teor de água da região basal das folhas caiu significativamente, ao contrário das regiões mediana e apical, sendo que a adição de uréia no oitavo dia na solução não alterou esse padrão. Após o período de oito dias de exposição ao PEG, a porção apical mostrou um aumento significativo na atividade PEPC e acúmulo noturno de citrato e malato, sendo esse último o principal ácido acumulado. Esses resultados indicaram que a porção apical de folhas destacadas pode aumentar a expressão do CAM quando submetida à falta d\'água. Adicionalmente, os resultados obtidos para as folhas mantidas em solução de PEG mostraram um aumento significativo da atividade da urease na porção apical no período noturno. Conjuntamente observou-se um maior acúmulo do CO2 proveniente da quebra da uréia nas regiões próximas aos cloroplastos, vacúolos e paredes, indicando que provavelmente o gás carbônico esteja sendo utilizado. Numa condição em que o CO2 é um fator limitante para a planta, a uréia poderia ser de grande importância ecofisiológica. Portanto, sugere-se que a uréia além de ser uma fonte nitrogenada, seja também uma fonte de carbono para as bromélias com tanque / Urease is a very important enzyme in the hydrolysis of urea, providing nitrogen to the plant. Previous studies developed in our Laboratory-IBUSP showed the preference of the epiphytic tank-bromeliad, Vriesea gigantea, for urea as a nitrogen source, and the localization of urease in the plasma membranes and cytoplasm of leaf cells. Recent evidences obtained also in our laboratory suggested a possible use of the CO2 generated by hydrolysis of urea. Even with these results, it is not known yet if in a water shortage situation the plant would possess an even higher preference for urea (reflected by an increase of urease activity), as in this situation the stomata are closed and the influx of atmospheric CO2 into the plant is limited. The analyses were made in three different leaf portions: apex, middle and basal. With the aim of characterizing the photosynthetic state of the leaf, was measured the relative water content, nocturnal organic acid storage, and enzymatic activities of phosphoenolpyruvate carboxylase (PEPC) and malate dehydrogenase (MDH). In addition, after 8 days of drought (by exposure to a solution containing 30% of polyethylene glycol - PEG), the detached leaves were treated with urea, and the urease activity and CO2 accumulation by cytolocalization were measured. The apical portion showed a significant increase of PEPC activity and nocturnal storage of citrate and malate, indicating that the apical portion is capable of increasing Crassulacean acid metabolism (CAM) expression under water shortage. In addition, in the apical portion of leaves kept in PEG and urea showed higher urease activities and CO2 accumulation at night than the control. CO2 buildup from urea hydrolysis was observed next to the chloroplasts and wall cells. Once in a limited CO2 situation to the plant, as is that case of water shortage, the results presented in this survey suggest that urea would be a highly important nitrogen source in the ecophysiology of plants. Therefore, besides urea being a nitrogen source, it could also be a source of carbon at least for epiphytic tank-bromeliads

Made available in DSpace on 2016-05-02T13:54:21Z (GMT). No. of bitstreams: 1 AndreVilelaPortugal-dissertacao.pdf: 317174 bytes, checksum: 65c3cef9f280c4503fc3dcc6e9c97aa0 (MD5) Previous issue date: 2012-10-23 / In corn crop, nitrogen is the nutrient most required, which further affects their productivity and which further onerous the cost of production. The purpose of this study was to evaluate sources of nitrogen in corn growth in tillage system. The experiment was conducted at the Vitoria farm, located in the city of Alfenas - MG, in a area of the first year of tillage system. For this, it was used the transgenic corn hybrid Impact of Syngenta, and it was employed random blocks design experimental, with7 treatments and 4 replications, totaling 28 plots. The treatments applied consisted: Control (without nitrogen in coverage); 100 Kg ha-1 of nitrogen in coverage, with ammonium nitrate, without incorporation; 100 Kg ha-1 of nitrogen in coverage, with urea, without incorporation; 100 Kg ha-1 of nitrogen in coverage, with urea and incorporation; 100 Kg ha-1 of nitrogen in coverage, with ammonium sulfate, without incorporation; 100 Kg ha-1 of nitrogen in seeding, with controlled release fertilizer, without incorporation; 50 Kg ha-1 of nitrogen in seeding, with controlled release fertilizer, without incorporation. The assessments of the experiment were performed, after 154 days, according to the parameters: grains productivity, number of grain rows per cob, weight of 1,000 grains, number of grains/row in each cob and number of grains per cob. With this study it can conclude that: the common urea, ammonium sulfate and ammonium nitrate showed similar performance and economic returns in corn crop tillage system; the incorporation of urea did not improve grain productivity and components production in corn growth in tillage system, the controlled release fertilizer is not feasible from an economic standpoint in corn growth in tillage system. / Na cultura do milho, o nitrogênio é o nutriente mais exigido, que mais afeta sua produtividade e o que mais onera o custo de produção. Objetivou-se com o presente trabalho avaliar fontes de nitrogênio no cultivo de milho em sistema plantio direto. O experimento foi realizado na fazenda Vitória, situada no município de Alfenas MG, em uma área de primeiro ano de plantio direto. Para tanto, utilizou-se o híbrido de milho transgênico Impacto da Syngenta, e empregou-se delineamento experimental em blocos ao acaso, com 7 tratamentos e 4 repetições, totalizando 28 parcelas. Os tratamentos empregados foram constituídos por: Testemunha (ausência de N em cobertura); 100 Kg ha-1 de N em cobertura, com nitrato de amônio, sem incorporação; 100 Kg ha-1 de N em cobertura, com ureia, sem incorporação; 100 Kg ha-1 de N em cobertura, com ureia, com incorporação; 100 Kg ha-1 de N em cobertura, com sulfato de amônio, sem incorporação; 100 Kg ha-1 de N na semeadura, com fertilizante de liberação controlada, sem incorporação; 50 Kg ha-1 de N na semeadura, com fertilizante de liberação controlada, sem incorporação. As avaliações do experimento foram realizadas, após 154 dias, de acordo com os seguintes parâmetros: produtividade de grãos, número de fileira de grãos por espiga; peso de 1.000 grãos, número de grãos/fileira em cada espiga e número de grãos por espiga. Com o presente trabalho podemos concluir que: a ureia comum, o sulfato de amônio e nitrato de amônio apresentaram desempenho e retorno econômico semelhantes na cultura de milho em sistema plantio direto; a incorporação da ureia não favoreceu a produtividade de grãos e os componentes de produção no cultivo de milho em sistema plantio direto; o fertilizante de liberação controlada não é viável do ponto de vista econômico no cultivo de milho em sistema plantio direto.

Nitrogênio é o nutriente mais utilizado mundialmente na agricultura devido promover grandes aumentos de produtividade e de qualidade, porém durante seu uso pode haver perdas de N por lixiviação e volatilização. O uso de inibidores de urease e de nitrificação podem aumentar a eficiência de uso de adubos nitrogenados. Objetivouse: a) estudar doses e fontes de nitrogênio na produção de cana-de-açúcar (Saccharum spp.) colhida sem despalha a fogo e avaliar a resposta desta cultura em aplicação do N na superfície do solo; b) avaliar a eficiência do uso de dicianodiamida em solos de diferentes texturas, com e sem a presença de palha, em estudo de incubação com sulfato de amônio; c) avaliar a eficiência de DCD e DMPP em solos do Brasil e da Alemanha em estudo de incubação e d) avaliar a eficiência de DCD e de NBPT na volatilização de amônia e na taxa de nitrificação de uréia. Houve aumento de produção de colmos de cana-de-açúcar nas doses de 0, 50, 100 e 150 kg ha-1 de N, porém não houve diferença das diferentes fontes nitrogenadas, mesmo havendo redução de volatilização de NH3 da uréia com o uso de NBPT, em torno de 60%. Houve redução da taxa de oxidação de amônio como uso de DCD, com maior eficiência no solo de textura média e, consequentemente menor formação de nitrato. Com a redução da taxa de nitrificação houve uma menor acidificação do solo. Houve redução da população de microrganismos nitritadores com o uso de DCD. O uso de inibidores de nitrificação (DCD e DMPP) retardou o processo de nitrificação em todos os solos (alemão e brasileiros), porém, com uma eficiência bem mais acentuada no solo arenoso. Houve maior eficiência do DCD nos primeiros 10 dias de incubação devido seu maior movimento no solo e no período final de incubação o DMPP foi mais eficiente devido sua menor degradação no solo. O NBPT foi eficiente em reduzir as perdas por volatilização, já o uso de DCD aumentou as perdas de N-NH3 da fonte uréia e diminuiu a eficiência do NBPT quando aplicado em conjunto com este, independente da dose. O DCD foi eficiente em diminuir o processo de nitrificação e não teve influencia na sua eficiência quando foi utilizado em associação com NBPT. / Nitrogen is the most world widely applied plant nutrient in agriculture because promote high yield and quality increases but, during youre using in agriculture losses by volatilization and leaching can occur. By using urease and nitrification inhibitors the nitrogen fertilizers efficiency can be increase. The objectives of this study was: a) study rates and sources of nitrogen fertilizers on sugarcane (Saccharum spp.) production harvested without burning and evaluate the response of this crop to over trash applied N; b) evaluate the efficieny of using DCD in different texture soils, with or without sugarceane trash, in a icubation experiment with amonium sulphate; c) evaluate the efficiency of DCD and DMPP in Brazilian and German soils in a incubation experiment and d) evaluate the efficiency of DCD and NBPT on ammonia volatilization and nitrification process of urea. Sugarcane yields increase with 0, 50, 100 and 150 kg ha-1 de N rates, but not with different N sources. With using NBPT ammonia volatilization was about 60% less, but also didnt increase sugarcane yield. Ammonium oxidation process in incubation study was inhibited with DCD use and, this inhibition was high in the soil with less clay. With reduction in nitrification process acidification of soil was lower. It was less nitrification microorganisms in soil with using DCD. With nitrification inhibitors (DCD and DMPP) the nitrification processa was delayed in all soils (german and brazilians), especially in sandy soil. DCD was more efficient in the next 10 days because have more mobility in soil wile DMPP was more efficient in the end of nitrification process because is more persistent in soil by his slow degradation process. The use of NBPT with urea is efficient to reduce ammonia volatilization wile urea treated with DCD these N loss is increased. When urea is treated with DCD and NBPT together the ammonia volatilization less is more than NBPT alone, but less of total ammonia volatilization of urea alone. DCD alone is efficient in inhibit nitrificatio

O nitrogênio desempenha função essencial na fisiologia das leveduras e em fermentações com alta concentração de açúcares propicia maior rendimento, eficiência e produtividade, além de proteger as células de levedura dos estresses osmóticos provocados pelas altas concentrações de açúcar e de etanol. Com o objetivo de verificar a influência da suplementação nitrogenada nos parâmetros fermentativos, mostos contendo caldo de cana concentrado a 25, 30 ou 35° Brix e suplementados ou não com ureia (16 mM) ou fosfato de amônio (24 mM), foram fermentados a 30°C por leveduras Saccharomyces cerevisiae (linhagens PE-2 ou CAT-1) em 6 ciclos consecutivos de 24h. Ao final de cada ciclo, foram analisados: a massa úmida (biomassa) por pesagem após a centrifugação; a viabilidade celular pelo método de coloração com eritrosina e a concentração de etanol em densímetro digital (Anton Paar DMA 4500), após destilação das amostras por arraste de vapor em destilador Tecnal TE-012 e açúcar por cromatografia líquida (HPLC). A concentração de nitrogênio total utilizável foi determinada pelo método da ninidrina, utilizando glicina como padrão. Em mosto contendo 30°Brix, a linhagem CAT-1, produziu teores de etanol, em média, de 12,9, 17,1 e 14,4% (v/v), respectivamente, nos tratamentos controle (T1) ou suplementado com ureia (T2) ou fosfato (T3). Nesta condição, a linhagem PE-2, produziu 14,9 (T1), 15,8 (T2) e T3 15,8% (v/v) e a massa úmida da CAT-1 aumentou de 7% para 16%, na presença de fosfato. Na fermentação do mosto 35°Brix, pelas duas linhagens, a suplementação com fosfato (T3) propiciou maior produção de etanol, aumento de massa úmida e manutenção da viabilidade celular. A levedura CAT-1, no tratamento com 30° Brix, produziu mais glicerol no tratamento com fosfato de amônio sendo quase 1g de glicerol por cada 1g de biomassa produzida. A suplementação com ureia teve efeitos benéficos na fermentação VHG possibilitando uma produção maior de etanol, e uma produção menor de glicerol face às outras suplementações nitrogenadas. / Nitrogen plays an essential role in the physiology of yeast and fermentation of high concentration sugars. It provides higher yield, efficiency and productivity, as well as protects yeast cells from osmotic stress caused by high concentrations of sugar and ethanol. To evaluate the influence of nitrogen supplementation on fermentative parameters, must containing concentrated sugarcane juice to 25, 30 or 35°Brix and supplemented or not with 16 mM urea or 24 mM ammonium phosphate were fermented at 30°C by PE-2 or CAT-1 yeast strains of Saccharomyces cerevisiae into 6 consecutive cycles of 24h. At the end of each cycle, cell viability by staining with erythrosine method, wet mass (biomass) by weighing; and the ethanol concentration in digital densitometer, after samples distillation were analyzed. The concentration of total usable nitrogen was determined by the ninhydrin using glycine as standard. In 30°Brix wort, CAT-1 strain produced averaged 12.9, 17.1 and 14.4% (v/v) of ethanol concentration, respectively, in the (T1) control or with (T2) urea or (T3) phosphate supplemented treatments. In this condition, the PE-2 strain produced 14.9 (T1), 15.8 (T2) and T3 15.8% (v / v) and the wet weight of CAT-1 increased from 7% to 16%, in the presence of phosphate. In the fermentation of the must 35°Brix by the two strains, supplementation with phosphate (T3) led to increased ethanol production, increased wet weight and maintenance of cell viability. CAT-1 strain, in 30°Brix, produced more glycerol upon treatment with ammonium phosphate being about 1 g glycerol per 1 g of biomass produced. Supplementation with urea had beneficial effects on VHG fermentation enabling increased production of ethanol, and a lower production of glycerol against other nitrogen supplementation.