Época de aplicação de nitrogênio no feijoeiro irrigado monitorada com auxílio de sensor portátil

• Autor(a) principal: Barbosa Filho, Morel Pereira
• Data de Publicação: 2009
• Outros Autores: Cobucci, Tarcísio, Fageria, Nand Kumar, Mendes, Patrícia Neves
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Repositório Institucional da UFLA
• Texto Completo: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1413-70542009000200010; http://repositorio.ufla.br/jspui/handle/1/6915
• topic: Phaseolus vulgaris L.; Manejo do nitrogênio; Clorofilômetro; Índice relativo de clorofila; Índice de suficiência de nitrogênio; Nitrogen management; Chlorophyll meter

Defining the optimal timing of nitrogen application on a crop is fundamental to increase the efficiency of N use, increase the productivity and reduce the cost of fertilizers. The aim of this study was to evaluate methods and timing of N application for the common bean crop. The management technique consisted of N application previous to sowing, N application based on local recommendations, and based on the sufficiency of N evaluated through leaf chlorophyll content determined by the Minolta SPAD 502 Chlorophyll meter. Grain yield obtained with the application of N prior to sowing was similar to other periods of N applications. The nitrogen application indicated by ISN < 90% was promising in predicting the necessity of N topdressing resulting in minus 60 kg N ha-1 and higher agronomic efficiency of N use. Minimum critical levels of chlorophyll reading to obtain 90% maximum grain yield of dry bean were 42 unit-SPAD at 30 days after emergence and 46 days after emergence at full flowering of the bean plant.