Nitrogen fertilization recommendation for corn cultivated under no-tillage

Recomendação de adubação nitrogenada para o milho cultivado em plantio direto

ABSTRACT

The amount of nitrogen (N) suggested for corn crop must meet its demand, maximizing yield and minimizing losses. Therefore, the objective of this study was to determine the recommendation of N fertilization for corn grown under no-tillage, using the method that considers the availability of N from the soil, the N requirement for the crop to reach the projected yield and the N-fertilizer recovery efficiency. The experiment consisted of four doses of N (0, 30, 70 and 95 kg ha^-1), arranged in randomized blocks, with five repetitions. N stock of 4,357.90 kg ha^-1 in the 0-20 cm soil layer provides corn plants with 52.83 kg of N ha^-1, corresponding to a mineralization coefficient of 1.2%. The N-fertilizer recovery efficiency and the harvest index show a progressive linear increase according to N doses. In projections of yields lower than 1,000 kg ha^-1, N fertilization is not necessary; however, in corn cultivation under no-tillage aiming at yield above 5,000 kg ha^-1, fertilization needs to be performed with doses above 100 kg of N ha^-1.

Key words:
Zea mays; recovery efficiency; N stock; soil fertility