Quantity and Quality of Dispersed Fine Particles after the Low‐Energy Water‐Dispersible Soil Test: Impact of the Initial Soil Matrix Potential

Core Ideas Moist initial conditions allow better discrimination of particle dispersion among soils. The nature of dispersed <2‐μm particles varies with the initial soil matrix condition. The low‐energy water‐dispersible clay test at two different initial conditions allows soil functioning analysis. Transfer of <2‐µm soil particles is a key process in the dispersion of pollutants and the textural differentiation of soil. Dispersion tests involving low‐energy water‐dispersible clay (LEWDC) are commonly used to indicate the stock of particles <2‐µm that can be mobilized. However, notable differences in LEWDC protocols exist. We discuss the impact of the initial soil matrix potential on the dispersion sensitivity of <2‐µm particles and the nature (mineralogy and particle size) of the dispersed particles. The dispersion sensitivity was more differentiated among soils with a high initial water content, which allows better soil discrimination. The nature of dispersed <2‐µm particles was closer to that of the bulk <2‐µm soil when moist initial conditions were considered, whereas enrichment in coarse clay minerals (with a particle‐size mode of around 2 µm) was observed with dry initial conditions. Performing the LEWDC test under both moist and dry initial conditions can be used to interpret soil functioning.