Evaluating the Impacts of Treated Wastewater and Groundwater Irrigation on Soil Quality and Physico-Chemical Properties

Agricultural irrigation accounts for approximately 90% of global freshwater consumption. As water scarcity intensifies, the reuse of treated wastewater (TWW) emerges as a viable and sustainable solution. While the reuse of wastewater can enhance soil properties, it also poses risks, such as increased soil salinization and heavy metal contamination. This study compared the effects of irrigation using TWW and groundwater (GW) on soil physicochemical properties in Algeria. The analysis is based on laboratory assessments of pH, electrical conductivity (EC), TDS, salinity, and calcium carbonate contents, along with soil quality index (SQI) in both irrigated and non-irrigated (control) soils. Statistical analyses revealed significant variations among treatments. TWW-irrigated soils exhibited higher pH (7.48 ± 0.04) but lower EC1 : 5 (262.5 ± 12.58 μS/cm) and salinity (0.127 ± 0.005 g/kg) compared to GW-irrigated soils. GW samples showed elevated salinity levels, suggesting the need for salt-tolerant crops, while TWW and control samples indicated optimal EC1 : 5 values. Soil samples were neutral to slightly alkaline, suitable for a wide range of crops, and exhibited high limestone content, indicating potential for cultivating calcicole species. Findings suggest that TWW reuse is preferable to GW, as it does not adversely affect soil properties and supports the sustainability of the water-soil-plant ecosystem. SQI results indicated TWW-irrigated soil had moderate quality similar to control, while 67.7% of GW-irrigated soils had poor quality. The implementation of agroforestry systems is recommended to mitigate salinity risks associated with high lime of Calcisols. Extensive monitoring of soil properties and inclusion of further indicators such as heavy metals, biochemical, and microbial traits are advisable.