Sensor based nitrogen management helped to improve fertilizer recommendations for various crops. The objective of this work was to develop algorithms for improved mid-season N management in sorghum (Sorghum bicolar L.). Two experiments were established at Stillwater and Lake Carl Blackwell, Oklahoma, 2004. Four pre-plant nitrogen rates (45, 90, 135, and 180 kg ha-1) were applied in a randomized complete block design in a plot size of 200 ft2. A GreenSeeker® hand held self-illuminated optical sensor measuring green and red normalized difference vegetation index (NDVI = (NIR– Red or Green)/(NIR+ Red or Green)) was used to determine vegetative differences between the treatments. NDVI readings were taken nadir to the ground and approximately 70 cm above the crop canopy at growth stage 3 (growth point differentiation), stage 5 (boot stage), stage 6 (half bloom) and stage 7 (soft dough stage). Results from correlation and regression analysis have shown both red (r2=0.69) and green (r2=0.67) NDVI were highly correlated with final grain yield at the stage of growth point differentiation. At the same stage grain nitrogen uptake was found to be positively correlated to NDVI readings. Growing point differentiation is a critical time for grain yield prediction and application of nitrogen.