A: PSD, pore size distribution; VPD, volume pore distribution.S S : M M Rainfall changes the physical state, pore system geometry, and structure of soils. Characteriza on of the soil pore system provides a realis c base to understand the reten on and movement of water in soil. The objec ve of this work was to es mate mul fractal parameters from Hg injec on porosimetry data on the uppermost soil surface layer as aff ected by simulated rainfall. Soil aggregates were sampled at the 0-to 2-cm depth in a loamy soil, both on a recently lled soil surface and on its disturbed counterpart a er 260-mm cumula ve rainfall. Pore size distribu ons (PSDs) were determined by Hg intrusion porosimetry from 0.005-to about 100-μm pore diameters on 10 samples per surface stage. The rainfall reduced aggregate pore volume, showing signifi cant diff erences between the pore space of the reference and the disturbed soil surfaces. A mul fractal analysis was performed by means of scaling of the moments ranging from −10 < q < 10 for all PSDs. Mean values of the entropy dimension, D 1 , and correla on dimension, D 2 , in the aggregate set sampled a er rain disturbance were lower than those of the reference stage; however, mean values of the diff erence Δ(D 1 − D 2 ), the Hölder exponent of order zero, α 0 , and widths of the le (α 0 − α q+ ) and right (α q− − α 0 ) hand sides of the singularity spectra f(α) a er rainfall ac on were higher than those of the ini al soil surface. Entropy dimension, D 1 , and the width of the le (α 0 − α q+ ) hand side of the f(α) spectra best discriminated between PSDs of the reference ini al soil surface vs. soil surface disturbed by rain.

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The specific surface area (SSA) of a soil is commonly estimated by the Brunauer–Emmett–Teller (BET) equation, which implies linearity between applied pressure and volume of adsorbate for a restricted scale range. Dinitrogen adsorption isotherms provide useful data for BET analysis, but they also contain additional information that may render useful a multifractal analysis. The objectives of this work were: (i) to find out if differences in soil use intensity cause changes in SSA assessed by the BET method, and (ii) to evaluate the usefulness of multifractal analysis for characterizing N2 adsorption isotherms also used for SSA determination. The study soils were a Vertisol and a Mollisol from Entre Ríos, Argentina. Treatments included: (i) native land never previously cultivated; (ii) permanent pasture; (iii) crop–pasture rotation; and (iv) continuous cropping. Vertisols had significantly greater SSA than Mollisols. Continuous cropping resulted in significant losses of organic matter (OM) content and aggregate stability decay in both soil types. Losses of OM by land use intensification significantly increased SSA in the Mollisol, but this trend was reversed in the Vertisol. All N2 adsorption isotherms exhibited multifractal behavior. Singularity spectra showed strongly asymmetric concave parabolic shapes with a left‐hand side much wider than the right‐hand one. Entropy dimension, D1, values were in the range 0.357 to 0.558 for the Vertisol and 0.401 to 0.658 for the Mollisol, which indicates that most of the measure concentrates in a small size domain. Several multifractal parameters were significantly different between soil types and soil use intensities.

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