[Predicting soil salinity based on spectral symmetry under wet soil condition].

There has been a growing interest in using spectral reflectance as a rapid and inexpensive tool for soil salinity monitoring in recent years. However, since soil moisture often exerts a tremendous influence on soil reflectance, the monitoring accuracy under various moisture conditions cannot fully satisfy the requirements of agricultural practice. In the present paper, a linear model was built to relate the spectral symmetry in the band of 1 370 - 1 610 nm with the salt content and moisture content of the saline soil based on regularly measured data of reflectance, soil moisture and salt content of the surface of 5 soil columns during the simulated evaporation process in laboratory. The results showed that the model was good with r greater than 0.8. By inversing the model, soil salt content then was predicted after moisture content was determined. The results showed that the prediction accuracy was acceptable with a root mean square error (RMSE) of 2.059 g x kg(-1) and an r of 0.656. The results demonstrated the feasibility of using spectral symmetry to predict soil salt content under various moisture conditions.