Nitrogen application on maize cultivated under notillage system in a year with normal precipitation and with “el-niño”

Abstract

In this study the split application of nitrogen and the maize crop pre-sowing nitrogen application under a no-tillage system followed by black oat, with two rainfall regimes were evaluated. Treatments were: 1. application of 150 kg N ha^-1 in pre-sowing and 30 kg N ha^-1 at sowing with 1997/98 “El-Niño” rainfall simulation; 2.  nitrogen application (CFS RS/SC, 1994), being 30 kg N ha^-1 at sowing,  and 30 kg N ha^-1 at 31 and 57 days after emergency (DAE), with “El-Niño” rainfall simulation; 3. without N application and “El-Niño”  rainfall simulation and; 4. nitrogen application (CFS RS/SC, 1994), with normal rainfall simulation. The experiment was conducted during 1998/99 growing season, at the Federal University of Santa Maria, in a completely randomized design, with two replications. A set of eight drainage lysimeters was used, protected from natural rainfall through an arch rain shelter. Leaf area index, plant height, above ground dry matter, grain yield and percent of N in maize grain and dry matter were evaluated. Nitrogen application on both water regimes had no effect on plant leaf area index, plant height, grain yield, percent of N in grains and N translocated to grains. Above ground dry matter and the amount of N carried out to shoot were smaller for the treatments submitted to normal rainfalls, compared to the ones that received N applications and “El-Niño”  rainfalls.