Economic analysis of corn inoculated with Azospirillum brasilense associated with nitrogen sources and doses

Abstract

Azospirillum brasilense is a bacterium known for its biological nitrogen fxation (BNF) in corn crops. However, there is a lack of comprehensive research defning how much mineral N should be applied to maximize the effciency of BNF and attain high, economically sustainable yields. Moreover, it would be interesting to investigate whether adding urea with NBPT urease inhibitor might increase BNF in grasses. Therefore, the aim of this study was to determine the effect of inoculation with Azospirillum brasilense associated with N sources and doses in a Cerrado biome soil by evaluating the grain yield of irrigated corn in economic terms. The experiment was conducted in Selvíria, MS, Brazil under a no-till system on a Latossolo Vermelho distrófco (Oxisol). The experiment was set up as a randomized block design with four replications in a 2 × 5 × 2 factorial arrangement consisting of two sources of N (urea and urea with NBPT urease enzyme inhibitor) and fve N doses applied as top-dressing (0, 50, 100, 150, and 200 kg ha-1), with and without the inoculation of seeds with A. brasilense. Inoculation with Azospirillum brasilense makes corn growth much more proftable, irrespective of the dose and source of N. Addition of 200 kg ha-1 N in the form of conventional urea coupled with inoculation with Azospirillum brasilense increases grain yield; however, the highest economic return is obtained with N applied at 100 kg ha-1 with conventional urea and inoculation.