TOPDRESSING NITROGEN IN MAIZE CROP UNDER CONSOLIDATED CONVENTIONAL AND NO-TILLAGE SYSTEMS

Abstract

Nitrogen is the nutrient most required by the maize crop, being often the most limiting one to grain yield. This research aimed to evaluate maize response to yield, agronomic traits, and efficiency of nitrogen (N) use, in relation to nitrogen topdressing, under conventional and no-tillage systems, in an area where soil management systems have been studied for twenty years (1985-2005), in the Universidade Estadual Paulista, in Botucatu, São Paulo State, Brazil. The experimental design was randomized blocks, in a split-plot arrangement, with four replications. The plots consisted of conventional and no-tillage systems and the subplots comprised topdressing nitrogen doses (0 kg ha^-1, 40 kg ha^-1, 80 kg ha^-1, 120 kg ha^-1, and 160 kg ha^-1). The nitrogen topdressing promoted significant increases in maize agronomic and nutritional traits, with maximum grain yield obtained with 151 kg ha^-1 of N. For the 90 kg ha^-1 and 145 kg ha^-1 nitrogen topdressing doses, the agronomic and recovery efficiency values were similar, when considered the conventional and no-tillage systems, respectively. The grain yield and maize agronomic and nutritional traits were not affected by soil management system.