Multi-electrode resistivity imaging

Multi-electrode soil imaging is a promisingway to investigate root systems by visualizing the distribution of soil volumes with different root densities, based on relationships between root biomass (RD) and electrical resistivity (ρ) of soils. Its most distinctive features are spatial coverage, rapidity, and minimum disturbance. Spatial patterns and frequency of ρ match those of RD, but calibration is needed and small RD values may not be clearly discriminated in soils with large ρ or variability in other features. Therefore it has been envisaged as: A nondestructive method for spatial quantification in two and three-dimensions A basis for spatially sound sampling A support for differential soil management Available data indicate that a definite response is not found for roots <2 mm and data sets are positively skewed. Statistical procedures to handle deviations from normality with the advantage of simplicity are discussed, as well as field of application, advantages, drawbacks, and future needs.