RATES AND TIME OF NITROGEN APPLICATION TO MAIZE IN A SOIL WITH HIGH-RATE OF ORGANIC-MATTER

This experiment was carried out for the purpose of evaluating the effe ct of different rates of N and the influence of the splitting of side- dressing fertilization on agronomic traits of corn. A soil with high o rganic matter content (5,7%) located on the highlands of Santa Catarin a state was used. Four rates (0, 50, 100 and 150 kg/ha) of N were test ed. In the first application period, N was totally applied when the pl ants presented five expanded leaves; in the second, half of the dosage was applied when the com presented five expanded leaves, and the othe r half, when de culture had nine expanded leaves. In 1990/91, there we re long periods of water deficit; in 1991/92, the rainfall was normal. In 1990/91 the yield was low and the response to applied N was high i n terms of increasing grain yield. On the other hand, when the water s upply was normal, com yield was high and the effect of N on grain yiel d was less pronounced than in 1991. There was no effect of the splitti ng of nitrogen side-dressing on grain yield and yield components.