Modified soil scattering coefficients for organic matter inversion based on Kubelka-Munk theory

The existing research into soil component inversion based on spectroscopic techniques has mainly focused on traditional statistical learning. However, the most prominent drawback of this approach is the difficulty in obtaining the soil components’ sensitive bands with explanatory inversion mechanisms. Whether for soil organic matter inversion or soil heavy metal inversion, there is still a lack of inversion models based on the physical theory of remote sensing. Hence, in this paper, an inversion model based on thickness correction using Kubelka-Munk (K-M) theory is proposed. Firstly, in this study, a soil thickness observation experiment based on K-M theory was undertaken. The impact of the soil thickness and the material of the container on the spectra was explored by selecting different experimental samples with different background container materials. A modified K-M thickness model was then developed by combining indoor spectral data. This allows the corresponding scattering coefficients and absorption coefficients for soil samples with different organic matter contents to be calculated. The optimal organic matter inversion model can then be constructed by the scattering coefficients, with the sensitive band at 2.197 μm. The results obtained in this study demonstrate the feasibility and superiority of the proposed method and further explain the sensitive bands of soil organic matter in hyperspectral data, with a determination coefficient accuracy of up to 0.97. The experimental results also demonstrate that the recommended soil thickness for soil samples should be more than 7 mm. In addition, when selecting background container materials, materials with obvious reflectance peak and valley characteristics should be avoided.