Emissão de óxidos de nitrogênio associada à aplicação de uréia sob plantio convencional e direto

Abstract

The objective of this work was to evaluate the NO and N2O emissions up to five days after the first nitrogen broadcasting fertilization with urea in a cornfield, in a Red Latosol, under conventional and no-tillage systems. The level of nitrogen broadcasting fertilization was of 60 kg ha -1. The experiment was conducted at Embrapa Cerrados, Planaltina, DF, Brazil, in a randomized block design, with three replications, beeing the third corn crop in rotation with soybean. NO and N2O fluxes were measured using PVC chambers installed in each plot. Higher NO fluxes were found immediately after (5.4 ng N cm-2 h-1) and three days (4.8 ng N cm-2 h-1) after N fertilization and irrigation. In the first day after fertilization, the NO emission decreased significantly to 1.9 ng N cm-2 h-1, and after five days, reached 1.2 ng N cm-2 h-1. N2O fluxes values were below the detection limit of 0.6 ng N cm-2 h-1. No significant differences in nitrogen oxides fluxes were found between plots under conventional and no-tillage systems.