Manejo de plantas espontâneas e fertilização nitrogenada em présemeadura do milho em plantio direto

• Ano de defesa: 2013
• Autor(a) principal: Rena, Frederico Cotta
• Orientador(a): Cantarutti, Reinaldo Bertola
• Banca de defesa: Ferreira, Lino Roberto , Rocha, Genelício Crusoé
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Solos e Nutrição de Plantas
• Departamento: Fertilidade do solo e nutrição de plantas; Gênese, Morfologia e Classificação, Mineralogia, Química,
• País: BR
• Palavras-chave em Português: Imobilização do N; Mineralização do N; Volatilização de Amônia
• Palavras-chave em Inglês: Immobilization of N; Mineralization of N; Ammonia volatilization
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/5516

The fractioned Nitrogen fertilization is a management strategy in which the largest fraction of the dosage is applied in topdressing. In Tillage System (TS), topdressing fertilization efficiency when using urea is compromised by the difficulty of incorporating the fertilizer. Nitrogen fertilization in pre-sowing, during the desiccation of the cover plants is a successful strategy, but in restricted conditions. The experiment aimed to evaluate the nitrogen fertilization in corn pre-sowing under Tillage system, with management of weed plants using pearly or grainy urea. The experiment was held in the experimental field of the Plant Science Department, Federal University of Viçosa during the 2010/2011 crop. The soil of the experimental area was a Red-Yellow Podsol grown for six years in Tillage System. The factors studied were cover plants prior to maize crop (grass Marandú - Brachiaria brizantha, oat - Avena strigosa and weed plants); Nitrogen dose applied at pre-sowing maize with desiccation of cover plants or the topdressing in the V4 stage of corn development (0, 50, 100, 150 and 200 kg ha-1), the application period of 200 kg ah-1 de N in pre-sowing in relation to the desiccation (20 days before, during the desiccation or 20 days after it) and form of urea (PETROBRAS pearly urea - UPP, PETROBRAS granulated urea - UGP and special granulated urea - UTI). These factors were combined in an incomplete factorial according to the Baconian matrix, totaling 29 treatments. Before desiccation, the amount of biomass cover plants was quantified then identified the species of weed plants and determined and content of N in the biomass. The N input through the waste was estimated. In treatment with fractioned application of 200 kg ha-1 N with different Nitrogen fertilizers at respective seasons to desiccation evaluated volatilization of NH3 through static semi-open collectors. The waste of ammonia was expressed regarding the dose of N applied. At the end of the growing cycle of corn (± 70 days after germination) were collected corn plants that have been properly processed for the analysis of the percentage of N. Estimated the amount of N accumulated in shoots of corn and based on these, an estimation of the apparent recovery of N fertilizer, considering or not the N contributed by residues of cover plants. Maize grain productivity was expressed with the grain humidity corrected to 13%. The results showed that nitrogen fertilization 20 days before drying, with weeds still alive provided greater N accumulation in biomass and reduction in C/N ratio. However this has not favored higher mineralization whereas management of weeds through herbicide application was not effective to enable the Nitrogen in the pre-sowing of the Tillage corn. The management of oats as cover crop by herbicide application was more effective to enable the Nitrogen fertilization in the pre-sowing. The special granulated urea was particularly effective for nitrogen fertilization in pre-sowing of maize under TS as management of cover crop through chemical desiccation.