The mineral nutrition of forage species is essential for the maintenance of sustainable livestock systems, since it can increase animal productivity per area. Panicum maximum is considered nutritionally demanding. However, the behavior of modern cultivars under nitrogen fertilization is unknown. The objective of this study was to evaluate the effects of increasing doses of nitrogen (N) on the structural characteristics, forage biomass, and crude protein (CP) of cultivar BRS Tamani. The experimental design was randomized blocks, and the treatments consisted of six N doses (0, 62.5, 125, 250, 375, and 500 N mg∙dm-3) using ammonium sulfate (AS) fertilizer, divided into three coverage applications under greenhouse conditions. Three cuts were made from all treatments, separated by an interval of 30 days. The interval between cuts was considered a split-plot effect. There was no interaction effect between the cuts and AS doses for the number of leaves tiller-1 or crude protein. However, there was an interaction effect for the leaf length, number of tillers, and biomass. The use of doses between 280 and 380 mg N∙dm-³ influenced the structural characteristics of the canopy and biomass of 'BRS Tamani' grass. The highest CP value was recorded in the first cut.