Abstract:
Soil salinity has today become a highly disastrous phenomenon that is responsible for crop failure worldwide and specially in
countries with low farmer incomes and food insecurity. Soil salinity is often caused due to water accumulation in fields due to
unscientific flood irrigation wherein plants intake the water leaving salts behind. It is, however, the sub-surface soil salinity
that affects the plant growth. These salts in sub-surface soil get trapped in root nodules of plants and prevent further water
intake. There have been very few studies conducted for sub-surface soil salinity estimation. Hence this study aims to estimate
sub-surface soil salinity (at 60 cm depth) for early stage of wheat crop growth in a simplified manner using freely available
satellite data, which is a novel feature and prime objective in this study. The study utilizes Sentinel-1 SAR (Synthetic Aperture
RADAR) data for backscatter coefficient generation, Sentinel-2 multispectral data for NDSI (Normalised Differential Salinity
Index) generation and on ground equipment for direct collection of soil electrical conductivity. The data were collected for two
dates in November and December 2019 and one date for January 2020 during the early stage of wheat crop growth. The dates
were selected keeping in mind the satellite pass over the study area of Rupnagar on the same day. Ordinary Least Squares
regression was used for modelling which gave R2-statistics of 0.99 and 0.958 in training and testing phase and root mean square
error of 1.92 in modelling for soil salinity estimation.
