Azospirillum brasilense associated with nitrogen fertilization promotes improvement in macronutrient contents of maize plants

The lack of studies on the benefits of growth-promoting bacteria associated with sources and doses of nitrogen fertilizers in maize in tropical regions has raised many doubts on the use of nitrogen management, as well as recommendation for the adequate dose for maize production. Therefore, the objective of this study was to evaluate the effect of the doses and sources of nitrogen associated with the absence and presence of seed inoculated with Azospirillum brasilense in the contents of N, P, K, Ca, Mg and S in the roots, culm and leaf of maize plants. It was used a completely randomized design, in a 4 x 2 x 2 factorial scheme, consisting of four nitrogen doses (0; 60; 120; and 180 kg ha-1 of N), two sources of N (common urea and urea treated with urease inhibitor) and absence and presence of inoculation with Azospirillum brasilense, with four replications. The results identified that the N doses positively influenced the concentration of N, P, and S in the culm of maize plants. The use of urea with urease inhibitor was not efficient in optimizing nitrogen fertilization, providing similar accumulations of macronutrients to common urea. The inoculation with Azospirillum brasilense promoted a concentration of 10.4% of N in the stem when compared to urea without inoculation. Seed treatment with Azospirillum brasilense at a concentration of 1 g / kg of seed at a dose of 180 kg ha-1 of N provided a higher content of macronutrients in corn, regardless of the sources of common urea or urea treated with a urease inhibitor