In Brazil, inoculation with Bradyrhizobium japonicum and Bradyrhizobium elkanii strains is the main form of Nitrogen (N) supply to soybean, but there are reports of the use of mineral N as a complement to biological fixation. The objective of this word was to evaluate the effect of different forms and phenological stagestimes of N application on the development and yield of soybean. The treatments include a control without N application and in all other treatments 10 kg ha-1 of N was applied, altering the phenological stagetime (V2, V4, R1 or R2) and the application form, namely, at sowing, broadcasted on topdressing or by leaf spraying. The application of N provided an increase in leaf area, shoot dry mass of shoot, number of nodules and dry mass of nodules in treatments with application of N at sowing and N at V2 on topdressing. For plant height, the treatment with N at V2 by leaf spraying was superior compared to control. The weight of one thousand seeds was not affected by N application. For grain yield the treatments with application of N by leaf spraying in V2 and R1 were highlighted. The greatest increase in grain yield on soybean is achievedreached with application by leaf spraying at V2 stage. The application of mineral N promoted an increase in grain yield and some of its components, as well as in morphological traits. However, the best way and phenological stage to provide that mineral N differed for the trait in question.
Keywords: nodulation, foliar fertilization, phenological stages