The study was conducted during agricultural year 2010, in Typic Inceptisol derived from limestone in the municipality of Baraúna in the state of Rio Grande do Norte, Brazil. The objective of this study was to define the best combination of nitrogen (N) and phosphorus (P) doses for economic production of corn, as well as the critical levels of N in leaf and P in leaf and soil. Seventeen treatments were studied, being 16 resulting from the combination between four doses of N (30, 60, 90 and 120 kg ha-1) and four doses of P2O5 (30, 60, 90 and 120 kg ha-1) and a control treatment, without application of these nutrients. The experimental design was in randomized blocks with four repetitions. The best combination of the N and P2O5 recommended to produce maximum economic efficiency in grain was 70 kg ha-1 of N combined with 120 kg ha-1 of P2O5. The critical levels of N in leaf and P in leaf and soil associated with maximum economic production efficiency of maize grain were, respectively, 32.93 g kg-1, 7.97 mg dm-3 and 3.11 g kg-1.
Zea mays L.; nitrogen fertilization; phosphorus fertilization; critical level
