Aplicação de ureia revestida em cobertura no milho irrigado sob sistema de semeadura direta

Abstract

The objective of this study was to evaluate the effect of nitrogen doses using urea or coated urea by polymers, in contents of nitrogen and chlorophyll in leaf, agronomic characteristics and yield of corn under no-tillage system, cultivated in Savanna region. The experiment was conducted during the growing season of 2008/09 and 2009/10, in Selvíria -MS in an Oxisol with loamy texture. A randomized block design with four replications was used, disposed in a factorial scheme 4 × 2, being: four N doses (0, 40, 80 and 120 kg ha-1) applied in topdressing, as urea in two forms (conventional and coated by polymers). The polymer that covers the urea is not efficient under the soil and climatic conditions of low altitude Savannah with the use of irrigation, because it provided similar results to conventional urea for agronomic characteristics and grain yield of corn. The increase of N dose influence positively the N and chlorophyll leaf contents, plant height, number of grains per line and mass of 100 grains. The topdressing application of 88 kg ha-1 of N provides maximum grain yield of corn, regardless of the form of urea used.