ASSESSMENT OF SOIL SALINITY USING GEOSPATIALTECHNIQUES AND GROUND DATA IN CENTRAL PUNJAB, PAKISTAN

Abstract

Soil salinity is among the cruelest and vicious environmental factor, affecting yield of most of the salinity sensitive crops due to excessive concentration of salts in the soil. Throughout the globe more than 100 countries are facing salinity problems and no continent is totally free of it. Hence it is important to devise a method for assessing and mapping soil salinity that are both rational and reliable. The current study was conducted on Shorkot and Toba Tek Singh tehsil of Central Punjab. Laboratory analysis data was acquired for 32 different soil samples from the study area and a relationship was developed between ground data and satellite data. Laboratory analysis for Electrical Conductivity (EC) and Sodium Adsorption Ratio (SAR) were performed for the selected samples. Landsat satellite (i.e., Landsat 4-5 and Landsat 8 OLI) imageries were used for indices development. Based on the ground data set (EC & SAR) and indices of 2020, the EC and SAR values for the past years (1996-2020) were calculated and classified into different classes. Inverse Distance Weighed (IDW) technique was used for mapping and soil classification was performed based on the ranges set earlier. The results after mapping confirm a major rise in salinity which disclose that the maximum EC and SAR values, in 1996 and 2020 were 4.94 dS/m and 10.01 mmol, and 8.23 dS/m and 59.73 mmol respectively. The minimum values of EC and SAR in 1996 were 3.44 dS/m and 7.16 mmol respectively, while oppositely in 2021 the minimum values analyzed were 5.28 dS/m and 11.11 mmol. On the other hand, the mean values of EC and SAR during 1996 were 4.74 dS/m and 23.24 mmol. A rapid increase in salinity level was observed during 2020 as the mean value of EC and SAR were 6.58 dS/m and 27.22 mmol. Overall, the percentage change in the mean value of EC and SAR were 38.8% and 17.2% respectively