The objectives of this research were to (i) assess the correlation between active and passive crop canopy sensors’ vegetation indices at different corn growth stages and (ii) assess sidedress variable rate nitrogen (N) recommendation accuracy of active and passive sensors compared to the agronomic optimum N rate (AONR). The experiment was conducted near Central City, Nebraska on a Novina sandy loam planted to corn on 15 April 2015. The experiment was a randomized complete-block design with four blocks. Treatment structure was one-way with a control plus four N rates (0, 65, 96, 129 and 161 kg N ha^-1). The N source for all treatments was urea-ammonium nitrate solution, which was broadcast pre-emergence on 22 April. Crop reflectance data was acquired using two different sensors: RapidScan (handheld, active) and Tetracam (UAS-mounted, passive). RapidScan was utilized to measure crop reflectance at growth stages V9, V13, VT and R4, and Tetracam at V13, VT and R4. For both sensors, NDVI and NDRE were calculated. The treatment receiving the highest N rate (161 kg ha^-1) was considered as the N-sufficient reference in order to calculate a sufficiency index, then used as an input in the algorithm for sidedress N rate determination. Passive and active sensor NDRE values were weakly correlated at different crop stages. This was likely the result of the difference in the red-edge band center between the sensors. Nonetheless, NDVI values from passive and active sensors were strongly correlated at crop stages V9 and V13. Using different VIs from either sensor did not produce a sidedress N rate that accurately resembled AONR at any crop stage. However, the AONR value observed for this field may have been biased due to high nitrate leaching conditions, which compromised grain yield response to N fertilizer. Nonetheless, sidedress N rate recommendation derived from both sensors were correlated when NDVI was used at V13. This indicates that both active and UAS-mounted passive sensors have the potential to derive sidedress N rate recommendation in corn at the V13 growth stage. However, caution must be taken to ensure that (i) the correct bands are selected and (ii) the reference area is actually N-sufficient.