Adubação nitrogenada, densidade de semeadura e espaçamento entre fileiras na cultura do milho em sistema plantio direto

Abstract

Among the practices and techniques employed for obtaining increased corn yield, the choice of plant arrangement and time of nitrogen topdressing are among the most important, associated with the choice of the hybrid and cropping system. The objective of this trial was study in no–tillage system, the influence of four times of application of nitrogen fertilization associated with three sowing rates and two interrow spacings for two corn cultivars in south Minas Gerais. On the site, two experiments in no–tillage system were established, the first one being set up with the spacing of 0.45 m and the second spacing of 0.90 m. In each experiment, two corn cultivars (P 30K75 and TORK), three sowing rates (55 thousand, 70 thousand and 85 thousand plants ha–1) and four times of application of nitrogen fertilization: 40 kg ha–1 of N applied on the occasion of sowing without any nitrogen topdressing; 40 kg ha–1 of N at sowing + 120 kg ha–1 of N topdressed soon after sowing; 40 kg ha–1 of N at sowing + 60 kg ha–1 of N topdressed at the stage of 4 to 5 leaves + 60 kg ha–1 of N topdressed at the stage of 7 to 8 leaves, 40 kg ha–1 of N at sowing + 120 kg ha–1 of N topdressed at the stage of 6 to 7 leaves. Nitrogen fertilization done into covering, in one or two applications influences in the height of the plants, the height of insertion of the ear and provides significant increases in corn grain yield.