Agronomic efficiency of conventional and polymer-coated urea applied at corn seeding

Abstract

Proper nitrogen fertilization is one of the most important requirements for high maize (Zea mays L.) yields. The nitrogen use efficiency (NUE) in Brasil is, however, very poor because nitrogen is prone to several transformations in soil like denitrification, volatilization of NH3, and in a lesser extend leaching, which may result in low utilization by the culture and increase the risk of environmental contamination. One method to increase NUE in corn is the use of controlled-release fertilizers (CRF) which has proven effective in many production systems. The aim of this study is to evaluate the effect of different combinations of polymer coated urea (PCU) and commercial urea (U), at two sites. We will evaluate agronomic traits, as well as the rate of accumulation of dry matter (DM) and N in shoots and roots along the corn cycle. The treatments will be the application of 180 kg N ha-1 at sowing, using two sources of N, U and PCU, applied in seven different managements (proportions), and a control (without N application). Additionally, it will be included treatment with the same rate of N (180 kg N ha-1), involving the splitting of total dosage, at sowing and topdressing (V4 stage), with incorporation of nitrogen fertilizer (as urea) in both cases. (AU)