Fig. 2
From: Benchmarking electrical methods for rapid estimation of root biomass
Coefficient of determination (r 2) between root dry mass and parallel capacitance, as a function of frequency. The semi-log plot was obtained from measurements for a 3T configuration, a frequency range of 0.5–20,000 Hz (log scale). Plants were grown in silt loam (plus symbol), loam (times symbol) and sandy loam (filled triangle) soils. The black dots represent the average of the three soil types. The maximum determination frequency f max for average is 116 Hz