Unravelling soil water dynamics in almond orchards characterized by soil-heterogeneity using electrical resistivity tomography

Characterizing soil heterogeneity helps to improve the management of the natural resources (mainly water, nutrients and soil itself) at the farm level and enhances crop growth and relative yield sustainability. In this context, the geophysical monitoring based on direct current methods (such as the Electrical Resistivity Tomography, ERT) can help to detect the soil heterogeneity by exploring the soil water variability. ERT time-lapse surveys were carried out in almond orchards characterized by different soil types in terms of structure (i.e. layered, light and heavy soil profiles) and texture features (i.e. prevalently clay loam versus sandy clay loam). Specifically, two-dimensional ERT surveys were combined with the monitoring of multiple soil-plant-atmosphere factors, including the components of the surface energy balance using an eddy covariance system, the soil moisture and the plant water status measured using a neutron probe and pressure chamber measurements, respectively. The interpretation of the ERT results together with the ancillary data has provided spatially and temporally distributed information about the soil water processes that occurred within the almond root-zone during irrigation, allowing us to identify where the most root-water uptake occurs and the delineation of the irrigation wet bulbs under micro-irrigations conditions.