The main goal of this study was to calibrate small unmanned aircraft system (SUAS) based vegetation indices with fertilizer-N application rate and yield for corn and sugar beet. It was hypothesized that canopy reflectance would change with increasing fertilizer-N application rates. The objectives of this study were (i) to determine the crop yield and quality in response to fertilizer application rates at two field sites, (ii) map vegetation indices of the experimental plots using drone-based optical sensors, and (iii) calibration of vegetation indices with crop yield. During 2017 and 2018 growing seasons, field trials were conducted to determine corn and sugar beet response to fertilizer-N application rates. In general, the use of optical sensors for quantitative and qualitative relationships were greater after the V6 growth stage in both corn and sugar beet. Early season moisture deficiency, disease, and crop size could impact the quality of the optical sensing data collection.