Predicting particle-size distribution using thermal infrared spectroscopy from reclaimed mine land in the semi-arid grassland of North China

Particle-size distribution is one of the vital properties of semi-arid and reclaimed soils that closely correlates with desertification. The thermal infrared (TIR) spectrum between 8 and 14 μm has the potential for particle-size monitoring in remote sensing. This study aims to investigate the characteristic TIR spectra of reclaimed mine soils and establish a particle-size prediction model. The characteristics of the reststrahlen band (8–9.5 μm) could be used to distinguish the coarse soil content that occurs in various land use and reclamation areas. A significant negative correlation was noted between the coarse sand content and the TIR spectrum (8–14 μm). The support vector machine calibration model exhibited a higher prediction accuracy for estimating the coarse sand content, with a cross-validated R2 of 0.95 and root mean square error (RMSE) of 3.01%, than the partial least squares regression model. These outcomes provide a theoretical basis and technical support for particle-size distribution estimations using TIR spectroscopy in semi-arid and reclamation areas. Hence, this study proposes that the spectral characteristics and model undergo further testing and optimization before wider application for the observation of semi-arid and reclaimed mine land ecosystems. •The mine reclaimed land soil had the higher coarse sand content.•The reststrahlen band (8–9.5 μm) can be used to distinguish different particle size.•Soil particles >0.05 mm can be predicted by the thermal infrared spectra.•The SVM model produced a more reliable prediction rather than PLSR model.