This study discusses measures for improving the precision of optical remote-sensing detection of soil salinity and the possibility of soil salinity detection at different depths of 0–10 cm, 10–30 cm and 30–50 cm… Click to show full abstract
This study discusses measures for improving the precision of optical remote-sensing detection of soil salinity and the possibility of soil salinity detection at different depths of 0–10 cm, 10–30 cm and 30–50 cm using optical remote-sensing data, and analyzes the mechanism by which deep-layer soil salinity influences the soil spectrum. The findings show that there is a high and significant correlation between soil-spectral reflectance and soil salinity, and that the correlation between soil-spectral reflectance and soil salinity decreases gradually from the blue band to the shortwave infrared band of ETM + images. The partial least squares regression model is used to estimate soil salinity in the 0–10-cm surface-layer, confirming that the selected soil-salinity-detecting bands of Band 1 and Band 4, the established difference soil salinity index, the derivative of the normalized differential vegetation index, and the deep-layer soil moisture can improve the precision of remote-sensing detection of surface-layer soil salinity. The precise estimation of the 0–10-cm surface-layer soil salinity with variables features an R2 = 0.752, an RMSE = 26.84 g/Kg, and a p = 0.000. There is a strong mediating effect between deep-layer soil salinity, 0–10-cm surface-layer soil salinity, and soil spectral reflectance in the study area; namely, deep-layer soil salinity influences soil spectral reflectance by influencing surface-layer soil salinity. There is a significant and very strong power function relation between 0 and 10-cm surface-layer soil salinity and deep-layer soil salinity. Based on this relationship, this study estimates deep-layer soil salinity using optical remote-sensing images.
               
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