SPECTRAL BEHAVIOR OF SALT-AFFECTED SOILS

For mapping and monitoring the spatial distribution of salt-affected soils using remote sensing data, a thorough understanding of their spectral behaviour is of paramount importance. The spectral behaviour of a few typical salt-affected soils of the Indo-Gangetic alluvial plain was studied by taking ground-based spectral measurements with the Exotech radiometer (model 100 EX) and measurements made by the thematic mapper (TM) onboard Landsat-5. Salt-affected soils, in general, showed relatively higher spectral response in the visible and near-infrared regions of the spectrum as compared to normal cultivated soils. Further, strongly saline-sodic soils were found to have higher spectral response as compared to moderately saline-sodic soils. The vegetation cover modifies the overall spectral response pattern of salt-affected soils especially in the green and red spectral bands. In addition, variation in the Sun elevation angle and moisture content were also found to modify the observed spectral response of salt-affected soils. Methodology and results are discussed in detail.