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An increasing number of electromagnetic (EM) sensors are deployed to measure volumetric soil water content (θ) for agricultural, ecological, and geotechnical applications. While impedance and capacitance sensors generally operate at frequencies between 20–300 MHz, time domain‐reflectometry (TDR) and‐transmissometry (TDT) function in the GHz range. In general, lower frequency sensors are less expensive but more sensitive to confounding effects of salinity, temperature, and soil textural variations. To simplify sensor application, factory‐supplied calibrations are often provided for different porous media types such as mineral, organic, and saline soils, or soilless‐substrates. The objective of the presented study was to evaluate the performance of eight commercially available EM moisture sensing systems (TDR 100, CS616, Theta Probe, Hydra Probe, SM300, Wet2, 5TE, 10HS) in seven well‐characterized and texturally varying soils using a standardized approach. The validity of factory supplied‐calibration relationships was evaluated and the influence of soil properties on the EM responses for θ measurements was observed. Results indicate that the factory‐supplied calibration relationships for groups of mineral and organic soils in general performed well, but some inconsistences were identified and suggestions for improvement are discussed. Soil‐specific calibrations from this study yielded accuracies of around 0.015 m3m−3 for 10HS, SM300, and Theta Probe, while lower accuracies of about 0.025 m3 m−3 were found for TDR100, CS616, Wet2, 5TE, and the Hydra Probe. These results are based on mineral soils having a large variation in texture, electrical conductivities below 2 dS m−1, organic matter below 10%, and specific surface areas of less than 50 m2 g−1.

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(1999), using the model of Turcotte (1986) and Tyler and Wheatcraft (1992), also found that three domains A particle-size distribution (PSD) constitutes a fundamental soil characterized the cumulative PSD of 19 soils. They assoproperty correlated to many other soil properties. Accurate representations of PSDs are, therefore, needed for soil characterization and ciated the power exponent in each domain with fractal prediction purposes. A power-law dependence of particle mass on dimensions defining scaling in the clay, silt, or sand particle diameter has been used to model soil PSDs, and such powerdomains. law dependence has been interpreted as being the result of a fractal A distribution of particle sizes reflects the relative distribution of particle sizes characterized with a single fractal dimenbalance of weathering and pedogenetic processes. Prision. However, recent studies have shown that a single fractal dimenmary minerals, generally present in the sand-and siltsion is not sufficient to characterize a distribution for the entire range size fractions, originate from weathering of a parent of particle sizes. The objective of this study was to apply multifractal material, while clay minerals are the result of weathering techniques to characterize contrasting PSDs and to identify multifracand synthesis of new minerals. The different origin of tal parameters potentially useful for classification and prediction. The the various size fractions may explain the various scaling multifractal spectra of 30 PSDs covering a wide range of soil textural classes were analyzed. Parameters calculated from each multifractal domains observed in soil PSD (Wu et al., 1993; Bittelli spectrum were: (i) the Hausdorff dimension, f(␣); (ii) the singularities et al., 1999). Grout et al. (1998) found that a single of strength, ␣; (iii) the generalized fractal dimension, D q ; and (iv) fractal dimension obtained from the model of Tyler their conjugate parameter the mass exponent, (q), calculated in the and Wheatcraft (1992) did not describe adequately the range of moment orders (q) of between Ϫ10 and ϩ10 taken at 0.5 distribution of particle sizes of three soils, and proposed lag increments. Multifractal scaling was evident by an increase in the multifractal techniques as a promising alternative to difference between the capacity D 0 and the entropy D 1 dimensions characterize PSD. Multifractal distributions may be best for soils with more than 10% clay content. Soils with Ͻ10% clay suited to represent the multiplicative action of the varicontent exhibited single scaling. Our results indicate that multifractal ous pedogenetic processes acting on a parent material parameters are promising descriptors of PSDs. Differences in scaling and resulting in a given distribution of particle sizes. properties of PSDs should be considered in future studies.