An attempt: Modified Semi-empirical approach based to retrieve soil fluoride using Sentinel-1SAR Data over Agricultural Patches

An Earth's crust contains 0.06 to 0.09% fluoride and its constituent, which affects the plant's growth and causes public health problems. This study was proposed for the Perambalur district, located in the southern part of India, and soils with high moisture availability to increase fluoride mobilization. Sentinel-1 data with an operational frequency of 5.4 GHz is used to perform a semi-empirical model. A modified approach is based on the relation between the salinity due to fluoride and the total salts. It makes sense that each saline-induced components provide a different loss angle value based on its concentration. Mostly, ion mobility in clay soil is limited by the interaction of the electrical potential and surface charges on the mineral and is controlled by soil moisture and permeability behavior. Based on the preceding, the salinity model DSDM is developed to distinguish saline soil from non-saline soil using conductance loss. Furthermore, the impact of fluoride contents is approximated from laboratory-based dielectric components (real and imaginary parts) of soil samples with high electrical conductivity under high and low fluoride conditions, making a loss angle of 4°1'. The dielectric behavior of the fluoride salt is investigated by relating the loss angle and real and imaginary parts of dielectric constants. An imaginary part of the dielectric component was sensitive to changes in dielectric loss and might be useful for predicting fluoride across vast areas over time. Finally, a fluoride value is estimated based on linear regression that considers conductance loss and field-observed fluoride values. The statistical results (R² = 0.86, RMSE = 1.90, and Bias = 0.35) obtained between the estimated and simulated values reveal that the C-band SAR data could delineate the fluoride levels over variable clay soil and soil with varying vegetation growth.