Agricultura Tropical

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http://repositorio.ufes.br/handle/10/17346
Programa de Pós-Graduação em Agricultura Tropical

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Navegando Agricultura Tropical por Autor "Andrade, Felipe Vaz"

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    Efeito da aplicação de fontes e doses de nitrogênio nos atributos químicos do solo, na extração de nutrientes e na produção do capim-mombaça
    (Universidade Federal do Espírito Santo, 2013-02-25) Rosado, Thiago Lopes; Almeida, Marcelo Suzart de; Andrade, Felipe Vaz; Gontijo, Ivoney; Passos, Renato Ribeiro
    The pastures represent the basis of bovine feeding in Brazil, which in its most part, are managed in extensive pastures. However, nutritional limitations, especially regarding nitrogen, contribute for the low forages production on the managed areas. The objective of this work was to evaluate the effect of the application of nitrogen sources and doses on the chemical soil attributes, on the development and extraction of mombaça grass nutrients. The experiment was developed among October 2011 and April 2012, on the Federal Institute of Espírito Santo campus Santa Teresa. The experimental design used was in randomized blocks, with three replications, in factorial scheme 3 x 6, with three nitrogenous fertilizers (urea, ammonium sulphate and calcium nitrate) and six nitrogen levels (0, 120, 240, 360, 480 and 600 kg ha-1), applied during the experimental period, totalizing 54 experimental units. The nitrogen doses were divided in 7 applications, and the treatments were applied at each 28 days, always after the forage cut, totalizing 7 cuts during the experimental period of 196 days. In each cut, the forage plant was collected with the assistance of an iron square of 50 x 50 and cut with a steel scissor. The material collected in each fragment was taken to the hothouse with air circulation, for the determination of previous dry matter. After drying, the samples were ground for the dry matter determination. The triturated material was conducted to the laboratory for evaluation x of the macronutrients on the vegetable tissue and these results were used on the quantification of the nutrients extraction by the forage. At the end of the experiment, samples of soil on the depth of 0-20 and 20-40 cm were still collected with assistance of an auger hole, to evaluate the effect of the treatments application upon the chemical attributes of the soil on the different depths. The experimental results showed that, according to forage production, Mombaça grass showed to be responsive to nitrogenous fertilization, and its answer in dry matter production and number of tillers, for the same nitrogen dose, depends on the used source. The best results for dry matter production and number of tillers were obtained with the use of calcium nitrate. It was observed with the vegetable tissue analysis, that the nitrogen application promoted an increase on the macronutrients extraction by mombaça grass, due to the higher forage production. Besides, the increase on the calcium proportion in the soil, due to the application of elevated calcium nitrate doses, resulted on the decrease of absorption and extraction of magnesium. For the soil chemical attributes, it was observed elevated acidification potential with the use of ammonium sulfate. The reduction provoked on the soil pH resulted in alterations on the levels of changeable aluminum, potential acidity and on phosphorus availability. Besides, elevated nitrogen doses as ammonium sulphate and calcium nitrate, promoted basis lixiviation, especially of potassium for the 20-40 cm layer.