Nitrogen accumulation in corn plant is highly influenced by N content in soil and by rate of its absorption by plant in a given growing stage. In order to compare the effects of N application methods on N accumulation and dry matter production by corn plant, an experiment was carried out in the state of Rio Grande do Sul, Brazil, over the 1998/99 growing season. Treatments consisted of two levels of water availability, one adequate to corn crop needs and the other with excessive water availability, and seven systems of N application to soil. The N application methods consisted of the following rates: 150 kg ha-1 topdress; 150 kg ha-1 applied before corn sowing (immediately after oat desiccation); 75 kg ha-1 applied before corn sowing + 75 kg ha-1 topdress; 60 kg ha-1 topdress; 60 kg ha-1 applied before corn sowing; 30 kg ha-1 applied before corn sowing + 30 kg ha-1 topdress; 60 kg ha-1 topdress; and check (without N before corn sowing or topdress). At sowing, 30 kg ha-1 of N were applied to all treatments. Urea was used as N source. Topdress N was applied manually, in a row, 5 cm from the corn row. There was no interaction between water level applied and N application systems. In the system with total N application before corn sowing, plants accumulated less N in relation to the system in which N was topdressed. The differences between the two systems were higher in the later stages of plant development, regardless of the water availability level.
Zea mays; no-tillage; Avena strigosa; methods of nitrogen fertilization