Quantitative Assessment of Soil Salinity Using Electromagnetic Induction Technique and Geostatistical Approach

Abstract

Assessment and monitoring of soil salinity is prerequisite for proper and timely decisions on reclamation and management of saline soil. Electromagnetic induction (EMI) method could be a cost effective and rapid method for assessment of soil salinity at large scale. EM-38, an instrument works on electromagnetic induction methods, was used for assessing spatial variation of soil salinity. Survey was carried out in vertical (EMV) and horizontal (EMH) modes at 200 m × 200 m grid spacing over 48 ha area of subsurface drainage site at village Mokhrakheri located in Rohtak district in Haryana, India. Based on the survey readings of high, moderate and low apparent conductivity, soil samples were collected from 8 sampling location points in field at 15 cm depth increment up to 90 cm depth for calibrating EM-38 observations. The soil samples were analyzed for soil salinity (ECe), cations (Ca2+, Mg2+ and Na+), anions (CO3 2-, HCO3 - and Cl-) and SAR using standard procedures. Sodium (Na+) and chloride (Cl-) ions were strongly correlated with apparent conductivity (EMV and EMH) measured by EM -38 as well as soil salinity (ECe). Therefore, Na+ and Cl- ions were mainly responsible for observed salinity in the field. Multiple regression analysis model based apparent conductivity (EMV and EMH) strongly predicted soil salinity (ECe). Quantitative evaluation of soil salinity for 0-90 cm profile indicated that more than 91% area of the field had salinity levels (ECe) above 4 dS m-1. It has been concluded that EM instrument is a reliable and rapid method for characterizing soil salinity at large scale for employing proper and precise reclamation measures for its effective utilization.