Imaging and Interpretation of Soil-Plant-Water Processes.

Noninvasive observation methods provide the possibility to investigate particular aspects of the uptake of water or solutes by plant roots in great detail. A relatively novel imaging technique in this context is neutron radiography. It has the potential to complement the valuable application of existing imaging methods by closing the gap between measurement of flow and transport phenomena for saturated porous systems via Magnetic Resonance imaging and X-ray imaging for identification of soil structures and roots in unsaturated soil. Though both imaging techniques have also been applied to look at water content distribution in soil, in this area neutron radiography may have the capability to be the most accurate and sensitive technique, especially when simultaneously detecting roots and water content. Of this new development results will be shown from imaging active roots and water content changes in soil on decimetre scale by neutron radiography including tomography. One aspect is root growth, also influenced by factors such as heavy metals or structures. Another one is the influence of roots and soil structures on the changes in water content distributions, for example after infiltration events. The interpretation of the observations in a mathematical framework requires an elaborated and time-consuming image processing effort. However, such procedures provide the chance to create a basis for detailed comparison of experimental data and mathematical modelling of processes in the soil-plant-water system.