Nitrogen oxides emission related to urea broadcasting fertilization under conventional and no-tillage systems

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.