Probability density function: A tool for simultaneous monitoring of pore/solid roughness and moisture content

We present a novel approach to multiscale fractal image analysis for monitoring the dynamics of the soil pore/solid network roughness due to moisture content changes. Roughness of the gray-level probability density function (PDF) of subsequent images of the drying soil was expressed in terms of its Hurst exponent (HPDF), which correlated significantly with the soil dielectric permittivity and gravimetric water content, as well as with micro-horizon depth and the temporal progress of drying. We documented an intermittent character of the water content dynamics, correlating with oscillations of the pore/solid interface roughness. Our technique of PDF roughness analysis of digital images, exemplified here for soil moisture monitoring, can be applied for monitoring the other complex systems, for instance plant growth in greenhouse.