Efeito da aplicação de fontes e doses de nitrogênio nos atributos químicos do solo, na extração de nutrientes e na produção do capim-mombaça
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2013-02-25
Autores
Rosado, Thiago Lopes
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Universidade Federal do Espírito Santo
Resumo
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
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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.
Descrição
Palavras-chave
Panicum maximum , Nitrogenous fertilizers , Capim-mombaça , Dry matter , Matéria seca , Soil acidity , Acidez do solo , Macronutrient absorption , Absorção de macronutrientes
Citação
ROSADO, Thiago Lopes. Efeito da aplicação de fontes e doses de nitrogênio nos atributos químicos do solo, na extração de nutrientes e na produção do capim-mombaça. 2013. 88 f. Dissertação (Mestrado em Agricultura Tropical) - Programa de Pós-Graduação em Agricultura Tropical, Universidade Federal do Espírito Santo, São Mateus, 2013.