Exploring the potential of airborne hyperspectral image for estimating topsoil organic carbon: Effects of fractional-order derivative and optimal band combination algorithm

•Potential of airborne hyperspectral image to estimate topsoil SOC was explored.•Fractional order derivative (FOD) was used for processing the reflectance spectra.•Optimal band combination algorithm was effective in extracting spectral index.•Combined use of FOD and optimal band combination algorithm improved the prediction.