Inoculation with Azospirillum brasilense in corn cultivated on cover crops and nitrogen doses

The use of growth-promoting and potentially nitrogen-fixing (N) bacteria in corn is a viable alternative to increase grain yield, reduce costs and environmental risks. However, the role of Azospirillum brasilense in the process of N utilization by plants needs to be better understood for its efficient use. Thus, the objective of this study was to evaluate the responses of inoculation with A. brasilense in corn cultivated in succession to cover crops associated with doses of mineral N. Two experiments were carried out in Augusto Pestana and Santa Maria (Rio Grande do Sul, Brazil), growing maize in succession to winter crops (black oats and forage radish), under doses of mineral N in top dressing (0, 75, 150 and 225 kg of N ha(- 1)), associated with A. brasilense inoculation. It was found that corn inoculation under black oat responded better to N rates applied to the thousand seed weight (TSW), grain yield (GY) (Augusto Pestana) and relative chlorophyll content (RCC) (Santa Maria). This was not evidenced when on forage radish residue, which quadratically adjusted the variables regarding N doses. In Santa Maria, the yield components were influenced by the interaction between the predecessor crop and the N dose, with a linear response to N doses when under black oat, obtaining isolated positive effects of inoculation for TSW and GY. It was concluded that the effect of inoculation of corn with A. brasilense is affected by residue from previous crops and N dose, with greater N demand in succession to black oat.