A multiple electrode device (MED) monitored four probe soil electrolyte conductivity (ECa) and its frequency response reveal that: (i) the average values of ECa gradients with frequency are +0.480, +6.960×10−3 and -3.836 × 10−3 dS m−1 (kHz)−1 in 10−2 to 0.5, 1 to 500 and 500 to 900 kHz respective frequency regions; (ii) the charge and potential of hydrated clay ion systemfor the peak ECa values vary from 65 to 75 × 10−19 Coulomb and 58 to 68 mV, respectively, (iii) the difference in MCa between the peak and valley ECa values is 1.78 dS m−1 and corresponds to the extremes of cationic desorption and adsorption on the claypartofthe soil and there by a factor of order 10 with ΔECa gives the tentative value of CEC of soil [18.0 cmol(p+)kg−1); (iv) in case of upper 50 cm soil column, the 1 kHz ECa average values recorded for a week deviate from the maximum and minimum ECa values by 8.9 per cent and provide a factor 4.02 to convert ECa to ECe; (v) a highly significant regional linear 10 Hz ECa responses to water content (W kg kg−1) are given by following relations:
Multiple electrode device, four-probe soil EC, frequency and water content responses of ECa, hydrated clay-ion system
