5. Conclusion(s)
The results (Refer to section 4) show that dual polarized SAR data along
with optical multispectral data if used in a synergetic way by taking
the advantages of both in terms of parameters that can be derived from
them can be used in a simple modelling approach for Root Zone soil
salinity estimation. Till now, most soil salinity studies were
concentrated only upon the surface soil salinity despite using highly
advanced datasets which were costly and sophisticated laboratory tests
of soil samples. This study not only conducted in a highly
cost-effective manner but also aimed at a simple, robust, and accurate
approach. The results show that the study has been highly accurate with
high values of R2-statistics of 0.997 and 0.958 in
training and testing stages, respectively. The accuracy and goodness of
model fit was further strengthened by the F-test and DW tests as
mentioned in results section. The novelties from this study are that
this study is innovative in a manner that it uses Microwave and Optical
data from satellites, thermal data from thermal imaging sensor from
field thus giving it a multi sensor approach for soil salinity
estimation at sub-surface level with high accuracy with a simple
approach. The study made use of freely available Sentinel-1 SAR and
Sentinel-2 optical satellite data, and no sophisticated laboratory
analysis hence making it cost-effective and time saving. The study
estimates root zone soil salinity from satellite data unlike most other
studies which were confined to surface soil salinity estimation using
remote sensing.
The study establishes a fact that remote sensing could be used
effectively and accurately for root zone soil salinity estimation which
is a major cause of crop failure and low yields world-wide. The findings
could be used for planning and taking timely measures for soil health
enhancement.
As an improvement and future extension to the work, a longer time series
SAR dataset could be utilised at higher wavelengths (L and S band) at
monthly intervals and soil salinity variations can be studied with crop
growth monitoring simultaneously. At present, the study has been
conducted for Rupnagar district of Punjab. Further the technique is
being implemented for other areas in India and is expected to deliver
similar results.