Electrical Resistivity Tomography of the Root Zone.

Understanding root scale processes and primarily those related to uptake in the root zone is very important for proper development of agricultural practices, efficient irrigation management, and proper estimation of vadose zone fluxes. Such understanding requires an ability to map in high spatial and temporal resolution the root zone. Electrical resistivity tomography (ERT) is a geophysical method that is very sensitive to the water content of the soil, which makes it of high suitability for root zone mapping and monitoring. In this talk we review the methodology and present several case studies that demonstrate the limitations of the method for root zone mapping. We will focus on high resolution mapping of the root zone of a single plant (bell pepper), and show where and when a plant takes its water. More than anything else our results show how lacking is our current knowledge and how difficult it is to assume a spatial distribution of the root uptake. We believe that ERT, being a relatively cheap non-destructive non-invasive method for root zone mapping can already be used at the field scale for various agronomic applications, while as a research tool some improvements are still needed.