Dynamics of Biopore Systems Investigated by X-Ray Microtomography.

X-ray microtomography (XMCT) is a well established tool in soil science to study soil structure dynamics non-invasively. Scanning and image analysis techniques have been continuously improved in the last decade allowing now a wide range of scales to be studied at ever greater detail. Quantitative parameters of pore space morphological properties derived from image analysis algorithms can help to improve water and nutrient uptake models explicitly accounting for structure related biophysical soil processes. In this presentation we will show examples on biopore systems developed by roots of three different preceding crops (alfalfa, chicory, fescue) and the effect of an existing biopore network on subsequent root growth. Large soil microcosms (20 cm diameter, 70 cm height) as well as smaller soil core samples (5-10 cm diameter and 4-10 cm height) have been scanned using two industrial XMCT systems to resolve the root-induced pore space on the biopore network and single pore scale. Pore space architectures were quantified by image analysis to evaluate network properties (connectivity, channel length, tortuosity, ect.) and biopore interface areas, which both are important parameters controlling transport  and accessibility of roots to water and nutrients. The potential use of such metrics for an improved understanding of soil-root interactions will be discussed.