Remediating the adverse effects of treated wastewater irrigation by repeated on-surface surfactant application

This dataset contains data collected from field studies of water movement through the soil using electrical resistivity tomography (ERT), laboratory analysis of the soil chemical properties, and the measurement of the soil hydraulic properties. The field is irrigated with wastewater which has led to the development of soil water repellency. This study investigated if spraying the soil with 0,5 or 10 g/L of a non-ionic surfactant will remediate the soil water repellency. ***Objective of the study*** (1) Whether the application of a nonionic surfactant to TWW irrigated soil can eradicate soil water repellency (SWR), with regard to preferential flow pathways, (2) if ameliorating SWR can homogenize soil moisture and chemical distribution, and (3) whether it offers any agronomic (yield) benefit to the trees. ***Instruments*** All ERT measurements were carried out using SYSCAL Junior (Iris Instruments, France) multi-electrode resistivity meter. Soil analysis was done in a commercial lab according to standard procedures. The soil hydraulic property was determined using HYPROP2 (UMS, Munich, Germany) system. ***Description of the data in this data set*** The data included in this data set has been organized into separate excel sheets according to the figure list below: Fig. 1. Percentages of mean soil water content (a), saturation degree (b), and soluble organic matter (c) as a function of sampling depths Fig. 3. Spatial distribution of ER in TWW irrigated plots, treated with 0, 5 and 10 g/L surfactant #20. Fig. 4. Temporal changes in ER measured before, during, and after irrigation, in the TWW irrigated plot, treated with 0 g/L surfactant #20 (2018). Fig. 5. Temporal changes in ER measured before, during, and after irrigation, in the TWW irrigated plot treated with 10 g/L surfactant #20 (2018). Fig. 6. Temporal changes in ER measured before, during, and after irrigation. in the TWW irrigated plot treated with 0 g/L surfactant #20 (2019). Fig. 7. Temporal changes in ER measured before, during, and after irrigation, in the TWW irrigated plot treated with 10 g/L surfactant #20 (2019). Fig. 8. Average EC, Na, Cl, N-NO3, P-Olsen, K, Ca+Mg, SAR, and PAR levels, from the top (0 – 20 cm) and bottom (20 – 40 cm) sampling depths. Fig. 9. Mean values for Saturation degree, EC, Na, Cl, Total N, P-Olsen, K, (solid lines) along the transect, at 25 cm intervals, for 0 - 40 cm depth. Fig. 10. Average grapefruit yields (in kg) for the untreated, and for two surfactant-treated plots, and for the trees in the plots, for 2019 and 2020. Fig. S1 (same as Fig. 1) Fig. S2 (same as Fig. 2) Fig. S3. Temporal changes in ER measured before, during, and after irrigation in the TWW irrigated plot treated with 5 g/L surfactant #20 (2019). Fig. S4. Soil water retention curves for 0, 5, and 10 g/L surfactant #20 treated plots. Panels a-c represent 0 – 20 cm depth, while panels d-f represent 20 – 40 cm depth