Interaction between soil variability and maize nitrogen status assessment from Sentinel-2

Crop nitrogen (N) status assessment from remote sensing can be based on the estimation of the nitrogen nutrition index (NNI). It is possible to estimate NNI directly from vegetation indices (VI) or indirectly through the estimation of biomass or leaf area index (LAI) and canopy nitrogen content. In this study, different approaches for the estimation of NNI in maize were assessed. LAI retrieved from Sentinel-2 over-estimated measured LAI introducing excessive uncertainties in the estimation of critical N from allometric relationships between LAI and biomass. Vegetation indices including the red edge bands were more promising in the direct estimation of NNI.