Nitrogen fertilization regarding maize crop in a semi-arid region

The correct management of fertilization, with the use of adequate source and doses of nitrogen, allied to cultivars adapted to certain edaphoclimatic conditions, is essential to obtain high yields. Thus, the objective of this study was to evaluate the nutritional N status, the physiological status and the grain yield of maize as a function of the application of nitrogen fertilizer sources and doses in Sobral - CE, in the northeastern semi-arid region. The design was in randomized blocks, in the factorial scheme 5x3+1. The treatments consisted of the combination of five forms of urea: conventional urea; urea + enzyme inhibitor; urea + polymer; urea + enzyme inhibitor + B + Cu; and urea + coating with elemental S, in three doses of nitrogen: 30, 45 and 60 kg ha -1 , applied in coverage, in the V6 stage (six fully developed leaves), plus a control treatment without N. The maize variety studied was BRS Gorutuba. Nitrogen fertilization in maize coverage promoted greater increases in the content of leaf N, protein, SPAD index and grain yield, when compared to the control, without N. The highest grain yield of maize was obtained with the use of urea treated with urease inhibitor, at the dose of 47 kg ha -1 .