Monica Martins da Silva

Nitrogen doses and water balance components at phenological stages of corn

Determinar a intensidade dos componentes do balanco de agua no solo num certo volume de controle de solo e, por conseguinte, a definicao dos periodos mais provaveis de deficit hidrico para a cultura, esta relacionada ao conhecimento de fatores do solo, do clima e da planta. Avaliaram-se componentes da equacao do balanco de agua no solo para fases fenologicas do milho (Zea mays L.), sob sistema de plantio direto, adubado com 60, 120 e 180 kg ha-1 de nitrogenio. O experimento foi conduzido em Piracicaba, SP, num Latossolo Vermelho-Amarelo. A avaliacao foi feita nas safras 2004/2005 e 2005/2006 de milho dividindo-as em tres fases de acordo com a fenologia da planta. O defluvio superficial foi desconsiderado, e foram medidas a precipitacao pluvial (P), a drenagem interna (D) (ou ascensao capilar) na profundidade de 0,8 m, a variacao da armazenagem (Δh) na camada de solo de 0,0-0,80 m, e a evapotranspiracao real (ET) foi considerada como incognita da equacao. Tambem, avaliou-se o rendimento de graos de milho. De forma geral, os componentes da equacao do balanco foram alterados pelas doses de N, uma vez que nos tratamentos com aplicacao de N, o solo mostrou uma Δh relativamente menor que o tratamento sem N, refletindo em menor valor de D nesses tratamentos, sendo traduzido em maior absorcao pelas plantas bem como maior ET. A fase II de desenvolvimento das plantas apresentou maior ET como esperado.

Aplicação de nitrogênio no cultivo de milho, sob sistema plantio direto: efeitos na qualidade física do solo e características agronômicas

This research was developed in the experimental area of ESALQ-USP, city of Piracicaba , state of Sao Paulo, in a soil of sandy-clay texture and aimed to evaluate the soil physical quality and maize agronomic characteristics with maize crop under different N doses and different tillage systems. The experimental design consisted of randomized blocks with four replicates. Treatments consisted of three nitrogen doses (N) (60, 120, and 180 kg ha -1 ) and a control. The ammonium sulfate fertilizer was applied at 30 kg ha -1 N during seeding, and the rest was applied as sidedressing when the plants had between six and eight leaves. Were determined the bulk density, microporosity, macroporosity and total porosity of soil, at depths of 0.05, 0.15, 0.25, 0.35 m, and the maize components yield. The soil physical properties tend to change over time and N levels, especially with regard to soil macroporosity and microporosity, conditioned by the structural change of the soil.

Efeito da adubação nitrogenada nas propriedades químicas de um Latossolo, cultivado com milho em sucessão à aveia-preta, na implantação do sistema plantio direto - DOI: 10.4025/actasciagron.v29i5.741

The present study evaluated the effect of nitrogen levels and splittings on the chemical characteristics of a soil cropped with maize in succession to black oats at the establishment of the no tillage system. The experiment was carried out in a Red- Yellow Latosol (typic Hapludox), with 14% of clay in the 0-0.20 m soil layer. The work consisted of two maize crops (2003/04 and 2004/05) and a black oats one in between, as cover crop. The experimental design was randomized blocks in an incomplete factorial scheme, with four replications. Treatments consisted of nitrogen levels (60, 120 and 180 kg ha -1 ) and one control without nitrogen, besides the splittings (30 or 60 kg ha -1 at sowing, the balance in cover and 60 kg ha -1 at sowing, remaining top dressed). The following soil variables were evaluated: Ca, Mg, K, organic matter, P, H+Al, Al, sum of bases, CEC, pH and base saturation V(%). Ammonium sulfate fertilization top dressed promoted a pH decrease in all treatments after the second maize crop and the increase in the level of N decreased the contents of soil Ca, Mg and K.

Effect of levels and splittings of nitrogen on chemical properties of a Latosol cropped with maize in succession to black oats, under the introduction of the no-tillage system.

The present study evaluated the effect of nitrogen levels and splittings on the chemical characteristics of a soil cropped with maize in succession to black oats at the establishment of the no tillage system. The experiment was carried out in a Red- Yellow Latosol (typic Hapludox), with 14% of clay in the 0-0.20 m soil layer. The work consisted of two maize crops (2003/04 and 2004/05) and a black oats one in between, as cover crop. The experimental design was randomized blocks in an incomplete factorial scheme, with four replications. Treatments consisted of nitrogen levels (60, 120 and 180 kg ha -1 ) and one control without nitrogen, besides the splittings (30 or 60 kg ha -1 at sowing, the balance in cover and 60 kg ha -1 at sowing, remaining top dressed). The following soil variables were evaluated: Ca, Mg, K, organic matter, P, H+Al, Al, sum of bases, CEC, pH and base saturation V(%). Ammonium sulfate fertilization top dressed promoted a pH decrease in all treatments after the second maize crop and the increase in the level of N decreased the contents of soil Ca, Mg and K.

Efeito da adubação nitrogenada nas propriedades químicas de um Latossolo, cultivado com milho em sucessão à aveia-preta, na implantação do sistema plantio direto

The present study evaluated the effect of nitrogen levels and splittings on the chemical characteristics of a soil cropped with maize in succession to black oats at the establishment of the no tillage system. The experiment was carried out in a Red- Yellow Latosol (typic Hapludox), with 14% of clay in the 0-0.20 m soil layer. The work consisted of two maize crops (2003/04 and 2004/05) and a black oats one in between, as cover crop. The experimental design was randomized blocks in an incomplete factorial scheme, with four replications. Treatments consisted of nitrogen levels (60, 120 and 180 kg ha -1 ) and one control without nitrogen, besides the splittings (30 or 60 kg ha -1 at sowing, the balance in cover and 60 kg ha -1 at sowing, remaining top dressed). The following soil variables were evaluated: Ca, Mg, K, organic matter, P, H+Al, Al, sum of bases, CEC, pH and base saturation V(%). Ammonium sulfate fertilization top dressed promoted a pH decrease in all treatments after the second maize crop and the increase in the level of N decreased the contents of soil Ca, Mg and K.