Monitoring different irrigation strategies using surface ERT

The huge demand of fresh water for irrigation together with water scarcity encourages the reuse of wastewater as a water resource in agricultural practices. The efficient use of wastewater, combined with irrigation strategies, could led to save water within an integrated management of water resources. ERT (Electrical Resistivity Tomography) technique could represent an useful tool to estimate the crop water requirements, the soil moisture and the impact of using poor quality water on crop and soil. In an experimental site close to Bologna (north of Italy), two different water saving irrigation techniques, Partial Root-zone Drying (PRD) and Regulated Deficit Irrigation (RDI), combined with brackish secondary treated wastewater and fresh water were tested in an irrigated corn crop. Particularly, during an irrigation cycle, lasted almost 72 hours, soil drainage through water uptake by the roots and the structural changes of the soil due to the poor quality of the used irrigation water, have been observed by means ERT survey in order to support water management models. Site specific petrophysical relationships ?-? have been obtained in laboratory to convert electrical resistivity into soil moisture content. Water content images, derived by ERT, were calibrated both by means the soil water content measured in laboratory on the undisturbed samples, and the soil moisture sensors installed in the field.