The objective of this study was to determine adequate N level for modern upland rice (Oryza sativa L.) cultivars sown at 0.20 m row spacing under supplemental sprinkler irrigation. The effects of N levels (0, 40, 80, 120, and 160 kg of N/ha) on the yield of one cultivar (Maravilha) and three favourable upland rice lines (CNA7127, CNA7730, and CT7/15) were studied during three crop seasons, in Santo Antônio de Goiás, GO, Brazil, in a Dark Red Latosol. According to regression model used, the maximum rice grain yield was 5,523 kg/ha, obtained with 112.9 kg of N/ha. Considering the prices of N (R$1.20) and rice (R$ 0.20) practiced in Goiânia, on June/97, the economical N level was 87.3 kg/ha.
Oryza sativa; mineral nutrition; nitrogen
