Tecnologias de fertilizantes nitrogenados para ambientes de produção de milho (Zea mays L.) no noroeste do Paraná

Abstract

Improvements in nitrogen use efficiency (NUE) in corn production systems are necessary to decrease economic and environmental losses which are mainly caused by ammonia volatilization (NH3-N) loss. The objective of this work was to study the different nitrogen (N) fertilizer technologies through characterization of N sources, NH3-N volatilization losses and their effects on the nutrient concentration and yield of corn grown in clayey and sandy soils in Northwest Paraná. The treatments consisted of a control without N application as topdressing, three conventional N sources (urea, ammonium sulfate, and ammonium nitrate + calcium sulfate), and three enhanced-efficiency fertilizers: urea treated with N-(n-butyl) thiophosphoric triamide (NBPT) + Duromide, urea formaldehyde, and polymer-coated urea (PCU) + urea treated with NBPT and nitrification inhibitor (NI). The nitrogen losses by NH3-N volatilization were up to 46% of the N applied with urea. However, NI addition to urea increased N losses by NH3-N volatilization by 8.8 and 23.3% in relation to urea alone for clayey and sandy soils, respectively. N fertilizers technologies applied in topdressing on clayey and sandy soil presented the following decreasing order of losses by N-NH3 urea > URP + Ur-NBPT + IN > Ur-NBPT + Duromide > Ur-formaldehyde > ammonium nitrate + calcium sulfate > ammonium sulfate. Clayey soil was 38.4% more responsive than sandy soil to N fertilization. Ammonium sulfate and ammonium nitrate + calcium sulfate showed the best results, because increased corn yield in clayey soil and contributed to reductions in NH3-N emissions of 84 and 80% in relation to urea, respectively.