Nitrogen fertilization for summer corn in succession to cover crops under direct drilling system in Western Paran - Brazil

The quality of vegetal residues from crops and green manure can influence the mineralization/immobilization rate of nitrogen and the subsequent utilization of this nutrient by the following crops. The aim of this study was to evaluate the effect of nitrogen rates applied to the cover of summer corn, succeeding winter cover crops under direct drilling system. The experimental design consisted of randomized blocks with four replications in a scheme with subdivided plots. The main plot was composed of two crops previous to corn: Common oat (Avena strigosa Schieb), forage turnip (Raphanus sativus) and a fallow area (weed). The subplot consisted of four rates of nitrogen (0, 30, 60 and 120 kg ha -1 ). The production components analyzed were: Ear diameter, rows of grains/ear, mass of 100 grains and yield. Cover crops did not affect the components of corn production. The corn cultivated in succession to forage turnip showed responses to nitrogen fertilization.