This study aimed to determine the nitrogen application need to optimise the Forage Sorghum yield and the quality silage in regions of humid and mesothermal climate. For the agronomic evaluations of the hybrids, a completely randomised block design was adopted, while for silages evaluation, the design used was completely randomised. The treatments were: 0, 50, 100, and 150 kg of N.ha −1 , with four replications each. The results showed that there was an increasing quadratic effect (P < 0.05) for dry matter percentage (% DM) of the plant stem, plant height (PH), stem diameter (SD), and crude protein (CP) of the silage. The decreasing quadratic effect (P < 0.05) was observed for panicle size (PAS). Also, there was an increasing linear effect (P < 0.05) for the fresh matter production (FMP) and dry matter production (DMP), and linear decreasing (P < 0.05) for the levels of neutral detergent fibre (NDF) and gas losses (GL). Based on the nitrogen use efficiency of the plant and the silage quality, an application of 50 kg of N.ha −1 is recommended for forage sorghum grown in regions of humid and mesothermal climate.