Phytoremediation of Saline-Sodic Soils in Arid Regions Using Rubia tinctorum L.: Effects on Soil Chemical and Physical Restoration

Saline-sodic soils pose a significant limitation to sustainable agriculture in arid and semi-arid regions, primarily due to prolonged droughts, high evapotranspiration rates, and inadequate water management. Traditional reclamation approaches often depend on chemical amendments; however, phytoremediation using salt-tolerant plants offers an environmentally friendly and cost-effective alternative. This study evaluates the effectiveness of Rubia tinctorum L.—a salt-tolerant, medicinal plant—in improving the chemical and physical properties of saline-sodic soil under controlled column conditions. The performance of Rubia tinctorum L. was compared to Sesbania aculeata L., Cynodon dactylon L., and chemical treatments (gypsum at 50 and 100% of requirement, and sulfuric acid) using soil with initial ECe = 12.88 dS m–1, SAR = 23.8, and pH 7.7. All treatments were leached with 41 L of water over 30 days. Rubia tinctorum L. reduced SAR by 59%, comparable to the 65% reduction achieved by chemical amendments. Additionally, it significantly enhanced soil structure, increasing mean weight diameter (MWD) by 74.5% and saturated hydraulic conductivity by 88% compared to the control. These findings demonstrate the plant’s capacity to improve soil aggregation and water transmission, highlighting its potential as a dual-purpose species for both soil rehabilitation and economic value in arid regions. The study supports Rubia tinctorum L. as a sustainable strategy for reclaiming salt-affected soils and promoting resilience in dryland agricultural systems.