Calibration of Inductive Electromagnetic Meter for Determining Electrical Conductivity of UAS, Raichur Soil

Abstract

EM-38 electromagnetic induction sensor is a most useful instrument to determine the soil salinity. Significant positive correlation found between inductive electromagnetic meter (IEM) readings and saturated paste extract electrical conductivity (EC) revealed that this technique could be used for determination of soil salinity. However, calibration of the instrument is necessary for interpretation of instrument readings in terms of meaningful parameters of soil salinity. The calibration equations developed elsewhere may not predict electrical conductivity of UAS, Raichur soil accurately. So, in this study, calibration of EM-38 was carried out to find the soil salinity of experimental site soil. A multiple linear regression equation was developed which valid up to 20 cm depth after calibration of the instrument for experimental site soil and this equation considered reliable as it showed a significant positive correlation between predicted and measured soil salinity values. Co-efficient of determination (R2) value was 0.817 between predicted and measured EC values. While salinity measurements made with the EM-38 are not highly accurate, but measurements within reasonable accuracy can be made very rapidly. Hence, this equation enables the user of the EM-38 to derive a realistic index of salinity of soil under consideration in terms of EC.