Employing Electromagnetic Induction Technique for the Assessment of Soil Compaction

Abstract

An experiment on a sandy soil field was conducted to investigate the potential of determining soil compaction from apparent soil Electrical Conductivity (EC_a) measured by Electromagnetic Induction (EMI) technique. A soil conductivity meter (EM38) was used to measure EC_a under four soil Moisture Contents (MC) (4.965.336.94 and 8.0%) and a range of Soil Compaction (SC) levels (on the average, from 220 to 2070 kPa). At each MC and SC level, EM38 measurements were recorded at three EM38 heights above the ground (0, 20 and 40 cm) and at vertical and horizontal device orientation. Except at the MC of 8.0%, results revealed that the measured EC_a was proportional to SC at all considered soil conditions and modes of measurement (EM38 orientation and height). For all soil conditions and modes of measurement, an overall mean of the coefficient of correlation (R²) of 0.66 was observed between SC and EC_a at soil MC of up to 6.94%. Thus, EC_a measurement can be an indicator of soil compaction, given that the MC is below 7% in sandy soil. For both EM38 orientations, higher correlations between SC and soil EC_a (average R² of 0.90) were observed with the EM38 placed on the ground (0 cm height) compared to those achieved at 20 cm and 40 cm height, where the average R² values were 0.62 and 0.47, respectively. At 0 cm height and MC of up to 6.94%, higher correlations between SC and EC_a were obtained at vertical EM38 orientation (average R2 of 0.98) compared to those at horizontal orientation (average R² of 0.81).