Electrical resistivity tomography: A reliable tool to monitor the efficiency of different irrigation systems in horticulture field

Water management in agricultural systems is essential for optimal crop yields without incurring excessive water costs and wastage. The choice of irrigation method is crucial for better water management and distribution. The drip system appears to be among the best methods in the field of precision agriculture. In addition to the irrigation system, mulching with ridge plastic film to drain excess water is widely used to increase crop yields in terms of plant water availability. In this study, the time-lapse Electrical Resistivity Tomography (ERT), a not-invasive geophysical technique, is proposed as a simple and reliable method to evaluate the effectiveness of the irrigation systems and to monitor the changes in water content over time and over a volume of soil. ERTs data were compared to moisture ones retrieved from sensors that record continuously over time, but punctually. The ERT investigations were conducted in melon-growing lands in southern Tuscany (Italy). Measurements were carried out on two different fields in two periods: spring and summer. The aim of the work was to evaluate, by means of volumetric measures of the soil conductivity, the effectiveness of three different drip systems and of the mulch ridge. In both the monitored fields the ridge was created in a half portion of the field itself, while the other part of the land was left plat. Geoelectrical investigations associated with humidity sensors have shown that in the summer a too high mulch ridge quickly drains the irrigation water, bringing the root zone into a water deficit. The ERTs also provided good results relating to the irrigation system, demonstrating that a three-lines drip irrigation system, compared to a two-lines one, manages to distribute the irrigation water homogeneously, guaranteeing a constant water content for the plants over time.