965 resultados para Doses of nitrogen


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Pós-graduação em Agronomia - FEIS

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Considering there are few researches about the influence of seedlings fertilization on yield, this work was carried out in order to evaluate the effect of rates of nitrogen and potassium, applied by fertirrigation, in endive seedlings on yield. Two experiments were carried out, the first with four treatments, varying nitrogen rates, and the second with four potassium rates. In both, experimental design was randomized blocks, with four replications. In the first experiment, we utilized ammonium nitrate, weekly, at rates 0; 40; 80 and 120 mg of N L-1, while in the second experiment we utilized potassium chloride, weekly, at rates 0; 70; 140 and 210 mg of K2O L-1. The evaluated characteristics at seedling stage were shoot height, number of leaves, fresh and dry shoot weight. At harvesting, we evaluated plant height, diameter, number of leaves and fresh weight. Potassium rates did not influence all characteristics, at seedling and at harvesting stages. For all seedling characteristics, there was linear increasing depending on nitrogen rates. But, for plant fresh weight, diameter and number of leaves at harvesting, the effect was quadratic. The highest fresh weight and number of leaves at harvesting were obtained with 90 mg of N L-1.

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The purpose of this study was to investigate the influence of potassium and nitrogen on the severity of black rot and yield of head. The experiment was carried out in split plots with factorial subplots, in randomized blocks with four replications. In the plots we assessed the influence of inoculation (injured plants with distilled water and inoculated with Xanthomonas campestris pv. campestris) and in the subplots we evaluated the 4 x 4 factorial, potassium doses (0, 275, 550 and 825 kg ha-1) and nitrogen (0, 150, 300 and 450 kg ha-1). The hybrid Broccoli BRO68 was inoculated using the toothpick method at 64 days after sowing. We observed that potassium in the plant reduced the disease, but nitrogen increased disease. We estimated that the highest levels of potassum in the plant reduced the severity of the disease but lack or excess of nitrogen increased disease severity. The highest production of broccoli inflorescence was obtained at doses from 541 to 751 kg ha-1 of K2O and 286 to 328 kg ha-1 of N. However, when considering a balanced fertilization to obtain higher yield and size of inflorescences and greater resistance to black rot, the ideal doses are 283 kg ha-1 of N and 550 kg ha-1 of K2O.

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The efficiency of nitrogen fertilization for sod production can be increased by using slow-release sources such as sewage sludge compost, which, due to its characteristics can be a substitute of part or all inorganic fertilization for grass. No results were found for the use of sludge compost in sod production in Brazil. This study evaluated the effect of rates of sewage sludge compost on the production of zoysiagrass. Treatments consisted of five rates of composted sewage sludge compost (0, 12, 24, 36 and 48 Mg ha-1, on a dry basis), plus a treatment of inorganic fertilization (300 kg ha-1 N, 80 kg ha-1 P2O5, and 200 kg ha-1 K2O). The results indicated different mineralization rates of the organic compounds present in the sludge; 120 days after sludge application, more Mg (100 %), K (90 %) and N (67 %) has been released than S (57 %), P (40 %) and Ca (31 %). The use of composted sewage sludge for zoysiagrass adequately supplied nutrients when applied to the soil surface at rates more than 36 Mg ha-1. After sod cutting, the rates of sewage sludge compost provided a linear increase in potential soil acidity, soil contents of OM, P, S, Fe, Cu, Mn, Zn, Cu and Ni, and linear decrease in pH, soil concentration of Ca and Mg and base saturation. Compost rates, increasing from 0 to 48 Mg ha-1, reduced the sod mass, reaching values of 4.0 kg/sod at the highest rate. High compost doses (36 and 48 Mg ha-1, respectively) also induced the highest resistance, with values in the order of 35 and 33 kgf.

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Pós-graduação em Agronomia (Ciência do Solo) - FCAV

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Pós-graduação em Agronomia (Produção Vegetal) - FCAV

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Pós-graduação em Agronomia (Agricultura) - FCA

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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O objetivo do trabalho foi estudar as características morfogenéticas e estruturais do capim-Tanzânia, a produção de forragem, as perdas de nitrogênio (N) por volatilização, reservas orgânicas e a avaliação do sistema radicular sob doses de nitrogênio sob pastejo. O experimento foi instalado na área Fazenda Experimental de Iguatemi da Universidade Estadual de Maringá, no período de março de 2007 a março de 2008. O delineamento experimental utilizado foi de blocos completos ao acaso, com parcelas subdivididas com quatro repetições. Nas parcelas, encontravam-se as doses de N (0, 150, 300 e 450 kg ha-1 de N) e, nas sub-parcelas, as estações do ano. As perdas de N por volatilização foram quantificadas depois da adubação N (1, 2, 3, 6, 9, 12 e 15 dias). As amostragens das raízes foram realizadas nas profundidades de 0-10, 10-20 e 20-40 cm. A aplicação do fertilizante N na pastagem foi parcelada em três aplicações. A produção de massa seca total e de lâmina foliar de forragem respondeu linearmente até 282 kg ha-1 de N na estação do verão. A adubação nitrogenada exerce efeito positivo nas taxas de alongamento e aparecimento foliar, e no número de folhas vivas em plantas de capim-Tanzânia nas estações da primavera e verão. Elevadas adubações nitrogenadas associada a intervalos menores de pastejo promovem uma maior porcentagem de lâmina foliar; no manejo de pastos de capim-Tanzânia sob lotação rotacionada com altura de 70 cm na entrada dos animais para o pastejo e saída com 30 cm de altura do resíduo. A interação entre o nível de adubação e o período depois da aplicação de uréia foi significativa para a variável volatilização acumulada de N-NH3. A aplicação da uréia acarreta perdas percentuais mais elevadas de N nos três primeiros dias após a aplicação. A perda média acumulada de N-NH3 no período para as três estações do ano... (Resumo completo, clicar acesso eletrônico abaixo)