Título:	Biodisponibilidade de fósforo residual em diferentes manejos de solo e adubação
Autor(es):	Oliveira, Luiz Eduardo Zancanaro de
Orientador(es):	Busato, Jader Galba
Coorientador(es):	Nunes, Rafael de Souza
Assunto:	Solos - teor de fósforo Solos - manejo Adubação
Data de publicação:	17-Abr-2019
Data de defesa:	23-Fev-2018
Referência:	OLIVEIRA, Luiz Eduardo Zancanaro de. Biodisponibilidade de fósforo residual em diferentes manejos de solo e adubação. 2018. x, 83 f., il. Dissertação (Mestrado em Agronomia)—Universidade de Brasília, Brasília, 2018.
Abstract:	Due to a high phosphate adsorbing capacity in highly weathered tropical soils, farmers who grow crops on these types of soils often apply high phosphorus (P) fertilizer doses, which are above the uptake harvested in agricultural products, creating a soil P surplus. Thus, after years of agricultural intensification, legacy P in important cropland areas has become a large reservoir of this nutrient, which can be exploited by farmers. However, there are not many studies that characterize the use of legacy P by plants in long-term experiment and field conditions. The objective of this study was therefore to evaluate the effect of soil management and previous fertilization on legacy P bioavailability, on the occasion of successive crops cultivated without the supply of this nutrient via fertilizers. To do so, an experiment located at Embrapa Cerrados, in Planaltina-DF, was cultivated with maize (Zea mays L.) or soybean (Glycine max L.) in the summer during 17 years, receiving 34.9 kg of P ha-1 year-1 in different tillage systems and P fertilizer managements: no-till (NT) or conventional tillage (CT), fertilized with reactive rock phosphate (RRF) or triple superphosphate (TS), broadcast in the field (B) or band-applied (BA). Soil samples were taken in order to evaluate the residual P in each situation. Corn was then grown for 4 more years without the addition of P, and new soil samples were taken after the last crop. The benefit of NT on grain yield and P use efficiency (ratio between grain yield and residual P before each cultivation of the non-fertilized phase) increases with successive crops grown in the absence of phosphate fertilization, what is explained by the greater P availability in the 0-10 cm layer in this system. Fertilizer placement did not change P use efficiency, while the use of RRF increased this index from the second year on of the non-fertilized phase. The surface layers and the inorganic fractions are mainly responsible for plant P nutrition in soils cultivated under NT, especially those previously fertilized with RRF or where the fertilizer was broadcast, whereas in the CT the share of each layer is more homogeneous, without evident effect P source and placement. NT has a higher capacity to replenish the P labile fraction from less available forms. There was an increase in the total and labile organic P levels despite a decrease in the organic carbon content in the CT, with the C/P ration approaching the one found in NT, which remained unchanged. Conservation soil management in NT and fertilization with RRF can be recommended as strategies to maintain legacy P bioavailability in tropical soils, contributing to a reduction in phosphate fertilizers demand.
Unidade Acadêmica:	Faculdade de Agronomia e Medicina Veterinária (FAV)
Informações adicionais:	Dissertação (mestrado)—Universidade de Brasília, Faculdade de Agronomia e Medicina Veterinária, Programa de Pós-Graduação em Agronomia, 2018.
Programa de pós-graduação:	Programa de Pós-Graduação em Agronomia
Licença:	A concessão da licença deste item refere-se ao termo de autorização impresso assinado pelo autor com as seguintes condições: Na qualidade de titular dos direitos de autor da publicação, autorizo a Universidade de Brasília e o IBICT a disponibilizar por meio dos sites www.bce.unb.br, www.ibict.br, http://hercules.vtls.com/cgi-bin/ndltd/chameleon?lng=pt&skin=ndltd sem ressarcimento dos direitos autorais, de acordo com a Lei nº 9610/98, o texto integral da obra disponibilizada, conforme permissões assinaladas, para fins de leitura, impressão e/ou download, a título de divulgação da produção científica brasileira, a partir desta data.
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