Forage sorghum is one of the prospective crops that may be used to produce biofuels in the future. Therefore it is of interest to find management practices that improve both the production of biomass yield and quality.  We present our observations of the effects the different rates of nitrogen fertilization have on biomass yield and tissue nitrogen content, and the correlations we found between tissue nitrogen content and tissue quality components such as ash, sucrose, lignin, cellulose, xylans and starch content, based on measurements performed by near infrared spectrophotoscopy.