Adubação nitrogenada e curva crítica de diluição de nitrogênio para a cultura do milho
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Data
2013-03-25
Autores
Orioli Júnior, Valdeci [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A recomendação da adubação nitrogenada para a cultura do milho deve ser constantemente atualizada, pois com frequência são lançados novos híbridos no mercado. Estes híbridos, normalmente, são mais produtivos e mais exigentes em N. A dificuldade de prever a disponibilidade deste macronutriente às plantas pela análise de solo torna ainda mais complexa a definição da dose de N a se aplicar. Atualmente, a dose de N para a cultura do milho é definida considerando-se o histórico da área e a produtividade esperada, e o estado nutricional da cultura quanto ao N tem sido avaliado por ocasião do pendoamento ou florescimento feminino, por meio da diagnose foliar. No entanto, se a deficiência de N for constatada neste estádio fenológico, não há mais possibilidade de se adotar medidas corretivas. Para contornar este problema pode-se adotar a curva crítica de diluição de N, pois esta permite acompanhar o estado nutricional nitrogenado da cultura em grande parte do seu período de crescimento. Assim, objetivou-se com este trabalho: 1) avaliar os efeitos de doses de N na cultura do milho; 2) subsidiar a recomendação da dose deste nutriente para a cultura e; 3) determinar e validar a curva crítica de diluição de N. Para tanto, foram conduzidos dois experimentos por dois anos agrícolas consecutivos (2009/2010 e 2010/2011) em solos distintos quanto à textura (Latossolo Vermelho eutroférrico argiloso - LVef e Latossolo Vermelho distrófico textura média - LVd). Adotou-se o delineamento experimental em blocos casualizados com seis tratamentos e quatro repetições. Os tratamentos consistiram da aplicação de 0, 60, 100, 140, 200 e 260 kg ha-1 de N. Para atingir os objetivos 1 e 2 avaliaram-se a densidade de massa seca de raiz (DMSR), o índice de área foliar (IAF), a concentração de N na folha, a produção de grãos...
The recommendation of nitrogen for maize crop must be constantly adjusted, because frequently are released new hybrids on the market. These hybrids, normally, are more productive and demand more N. The difficulty to predict this nutrient availability to plants by soil analysis makes more complex the definition of the rate of N to use. Nowadays, the N rate for maize is defined considering the area historical and the expected yield and the N fertilization efficiency has evaluated at tasseling or bolting, by foliar diagnosis. Therefore, if N deficiency is detected at this phenological stage, this is no possibility to adopt corrective measures. To work around this problem it can be adopted the critical nitrogen dilution curve, because it allows to follow the nitrogen nutritional status of the culture in great part of its development. Thus, the objective with this work: 1) evaluate the effects of N addition in maize; 2) subsidize the rate recommendation of this nutrient for the culture and; 3) determinate and validate the critical nitrogen dilution curve. So, there were conducted two experiments for two consecutive years (2009/2010 and 2010/2011) in distinct soil as its textures (clayey and medium texture). It was adopted the experimental design in blocks with six treatments and four replications. The treatments consisted of the application of 0, 60, 100, 140, 200 and 260 kg ha-1 of N. To achieve the objectives 1 and 2 evaluated the dry weight root density (DWRD), the leaf area index (LAI), leaf N concentration, grain yield, number of grains per ear, the mass of 1,000 grains and grain weight per ear. It was found that nitrogen fertilization increased the DWRD, however, only in the first 0.20 m depth. The LAI, the concentration of leaf N, the mass of grains... (Complete abstract click electronic access below)
The recommendation of nitrogen for maize crop must be constantly adjusted, because frequently are released new hybrids on the market. These hybrids, normally, are more productive and demand more N. The difficulty to predict this nutrient availability to plants by soil analysis makes more complex the definition of the rate of N to use. Nowadays, the N rate for maize is defined considering the area historical and the expected yield and the N fertilization efficiency has evaluated at tasseling or bolting, by foliar diagnosis. Therefore, if N deficiency is detected at this phenological stage, this is no possibility to adopt corrective measures. To work around this problem it can be adopted the critical nitrogen dilution curve, because it allows to follow the nitrogen nutritional status of the culture in great part of its development. Thus, the objective with this work: 1) evaluate the effects of N addition in maize; 2) subsidize the rate recommendation of this nutrient for the culture and; 3) determinate and validate the critical nitrogen dilution curve. So, there were conducted two experiments for two consecutive years (2009/2010 and 2010/2011) in distinct soil as its textures (clayey and medium texture). It was adopted the experimental design in blocks with six treatments and four replications. The treatments consisted of the application of 0, 60, 100, 140, 200 and 260 kg ha-1 of N. To achieve the objectives 1 and 2 evaluated the dry weight root density (DWRD), the leaf area index (LAI), leaf N concentration, grain yield, number of grains per ear, the mass of 1,000 grains and grain weight per ear. It was found that nitrogen fertilization increased the DWRD, however, only in the first 0.20 m depth. The LAI, the concentration of leaf N, the mass of grains... (Complete abstract click electronic access below)
Descrição
Palavras-chave
Milho - Cultivo, Analise foliar, Milho - Adubação, Fertilizantes nitrogenados, Nutrição - Avaliação, Nitrogen fertilizers
Como citar
ORIOLI JÚNIOR, Valdeci. Adubação nitrogenada e curva crítica de diluição de nitrogênio para a cultura do milho. 2013. v, 58 p. Tese (doutorado) - Universidade Estadual Paulista Júlio de Mesquita Filho, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, 2013.