Fig. 3From: Benchmarking electrical methods for rapid estimation of root biomassImpact of the stem contact electrode on the measured electrical capacitance of the plant–soil system. Plot of the mean relative difference between the parallel capacitance measured with a clamp and that measured with a needle, as a function of frequency, in 2T (filled square), 3T (filled triangle) and 4T (plus symbol) configurations. Differences are <6 % for frequencies <200 Hz in 3T configurationBack to article page