Using high-resolution satellite imaging to evaluate nitrogen status of winter wheat

Nitrogen (N) applications often increase crop yields significantly, but N needs vary spatially across fields and landscapes. The color of the wheat plant is sensitive to N status and may provide a means to accurately predict N fertilizer rates matching spatial variability. Previous researches have reported that remote sensing may contribute to N management decisions by collecting spatially dense information. The objective of this study was to determine the feasibility of using high-resolution satellite imaging for evaluating N status of winter wheat in the North China Plain. High-resolution images from a QuickBird satellite were taken on April 1, 2002 at booting stage of wheat with multi-spectral wavelengths (blue, green, red, and near-infrared). Correlation analyses indicated that all the broadband indices derived from the satellite images correlated well with sap nitrate concentration, SPAD readings, total N concentration, and aboveground biomass. The individual band reflectance values R, G, B correlated well with sap nitrate concentration, SPAD readings, total N concentration, and aboveground biomass. These results demonstrated the potential of using new generation high-resolution satellite imaging for large area wheat N status diagnosis.