Adubação nitrogenada com ureia de liberação controlada na semeadura do milho

• Autor(a) principal: Oliveira, Josimar Rodrigues
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5517
• topic: Amônia; Salinidade; Toxidez; Adubação; Ammonia; Salinity; Toxicity; Fertilization; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

The nitrogen losses by volatilization, leaching and denitrification drive research for new fertilizer that release the nutrients synchronized with crop demand. In the literature, the works are still few to evaluate technical and economical efficiency these fertilizes in relation to the traditional sources. We objective were: i) evaluate toxic effects of controlled release urea on the germination and initial growth of maize plant and ii) evaluate the possibility of perform the full nitrogen fertilization at planting with controlled release fertilizers. To this end have been developed two experiments. The first was conducted in greenhouse, using a factorial combination of two soils (clayey and sandy loam). Ten fertilizers (pearly urea, ammonium sulfate, ammonium nitrate and sodium nitrate and potassium double, boric acid and copper sulfate coated urea, sulfur coated urea, three forms of sulfur-polymer urea and one polymer coated urea. In this study was checked that the excessive absorption of nitrogen and its accumulation in the form of NH4 + in plant tissues is more harmful than the effects of NH3 in the soil atmosphere or the increase of salinity provided by the fertilizer. The toxicity symptoms are more pronounced in sandy loam soil, leading to stagnant growth and death of seedlings after emergence. The forms of sulfur coated urea or Cu and B, and urea coated with sulfur and polymers or only polymers not allow the application of high nitrogen levels in the planting. In the second study, conducted in the field treatments were formed by combining seven forms of urea, two doses of N (120 e 240 kg ha-1) and two application modes (installment or full dose in the groove). Forms of urea used were the same as applied in the first experiment. There was no reduction in germination, growth and development of maize plants. There was no difference in response between the forms of controlled release urea and urea pearly conventional.