Contribution of Azospirillum brasilense to nitrogen fertilization for maize crops planted successively to soybean crops

Maize is very important in Brazilian agribusiness: it is the second most produced grain in the country. Crops need to be fertilized, especially with nitrogen, to achieve high yields. This study aimed to evaluate the contribution of Azospirillum brasilense in maximizing the use of nitrogen by maize crops after soybean cultivation in the same soil. This study was carried out at the Experimental Farm of the State University of Minas Gerais (UEMG), Passos unit. The experiment consisted of planting maize in the same soil where soybeans had previously been grown, with a strip- and split-plot design. The seeds in one strip were inoculated with Azospirillum brasilense, and those in the other strip were not. Each strip was divided into 24 plots measuring 18 m², which received nitrogen doses as urea (0, 10, 35, 70, 140 and 210 kg ha−1 of N), in four replications. Seed inoculation did not result in statistical differences. The plots that received the treatment with chemical nitrogen fertilization exhibited the same results as those that did not, which can be explained by the previous soybean cultivation letting nitrogen in the soil and/or by the effect of Azospirillum brasilense.