Lysimeter experiments were conducted with sandy-clay-loam soil to study the efficiency of two amendments in reclaiming saline-sodic soil using moderately saline and SAR (sodium-adsorption ratio) irrigation water. Gypsum obtained from industrial phosphate by-products and reagent grade Ca chloride were applied to packed soil columns and irrigated with moderately saline (ECe = 2.16 dS m -1 ), moderate-SAR water (SAR = 4.8). Gypsum was mixed with soil prior to irrigation at application rates of 5, 10, 15, 20, 25, and 32 Mg ha -1 , and Ca chloride was dissolved directly in leaching water at application rates of 4. 25, 8.5, 12.75, 17.0, and 21.25 Mg ha -1 , respectively. The highest application rate in both amendments resulted in 96% reduction of total Na in soil. The hydraulic conductivity (HC) of soils receiving gypsum increased in all treatments. The highest HC value of 6.8 mm h -1 was obtained in the highest application rate (32 Mg ha -1 ), whereas the lowest value of 5.2 mm h -1 was observed with the control treatment. Both amendments were efficient in reducing soil salinity and sodicity (exchangeable-sodium percentage, ESP); however, Ca chloride was more effective than gypsum as a reclaiming material. Exchangeable Na and soluble salts were reduced with gypsum application by 82% and 96%, and by 86% and 93% with Ca chloride application, respectively. Exchangeable Ca increased with increasing amendment rate. Results of this study revealed that sodium was removed during cation-exchange reactions mostly when the SAR of effluent water was at maximum with subsequent passage of 3 to 4 pore volumes. Gypsum efficiently reduced soil ESP, soil EC, leaching water, and costs, therefore, an application rate of 20 Mg ha -1 of gypsum with 3 to 4 pore volumes of leaching water is recommended for reclaiming the studied soil.

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Fifteen soil profiles were taken from ArRamtha wastewater treatment plant, 65 km north of Amman. Twelve of them represent soil planted with barley and irrigated with wastewater for the past 2, 5, and 15 years. The remaining three profiles represented a control area that has been only rainfed. Soil samples were collected in four replicates from each depth in each soil profile. Field and laboratory experiments were conducted to study the effect of irrigation with treated wastewater on hydraulic properties of surface and subsurface vertisols. Soil infiltration rate (IR), hydraulic conductivity (HC), and water retention (at 33 kPa and 1.5 MPa) were measured. The application of wastewater for 2, 5, and 15 years reduced soil hydraulic conductivity, whereas the infiltration rate decreased for 2 and 5 years, compared with non-irrigated area. Sites irrigated for 15 years with treated wastewater are characterized by higher percentages of large cracks, therefore revealed the highest infiltration rate. Soil available water changed due to wastewater application in decreasing order of: control (rainfed), 15, 5, 2 years of wastewater application.

The removal of sodium salts from saline soils by salt tolerant crops, as alternative for costly chemical amendments, has emerged as an efficient low cost technology. Lysimeter experiments were carried out on a highly saline sodic soil (ECe = 65.3 dS m(-1), ESP = 27.4, CEC = 47.9 cmole+ kg(-1), and pH = 7.7) and irrigated with canal water (EC = 2.2 dSm(-1), SAR = 4.8) to investigate reclamation efficiency under four different treatments: control (no crop and no gypsum application) (C), gypsum application equivalent to 100% gypsum requirement (G100), planting sea orach (Atriplex halimus) as phytoremediation crop (Cr), planting sea orach with gypsum application equivalent to 50% gypsum requirement (CrG50). Soil salinity (ECe) and exchangeable sodium percentage (ESP) were significantly reduced compared to the control. Average ESP and ECe (dS m(-1)) in the top layer were 9.1, 5.8 (control), 4.8, 3.7 (Cr), 3.3, 3.9 (CrG50), and 3.8, 3.1 (G100), respectively. Atriplex halimus can be recommended as phytoremediation crop to reclaim highly saline sodic clay loam soils.

Phosphoric acid is increasingly used as a source of water‐soluble P, but it has not been widely tested for its effectiveness in reclaiming calcareous sodic and saline‐sodic soils relative to chemically equivalent rates of gypsum. In lysimeters experiments, we showed that a calcareous saline‐sodic soil can be ‘reclaimed’ using phosphoric acid and leaching with moderately saline irrigation water (sodium adsorption ratio = 4.1 and electrical conductivity = 2.2 dS/m). Phosphoric acid (50% pure) was dissolved directly in the leaching water at application rates of 450, 600 and 900 kg/ha, and phosphogypsum (80% pure) was mixed with soil prior to leaching at application rates of 15, 20, 30 and 40 t/ha. Phosphoric acid was more efficient than the chemical equivalent of phosphogypsum in improving soil hydraulic conductivity, and in reducing the exchangeable sodium percentage (ESP). The ESPs after leaching were: 10 (water only), 5.5–5.3 (phosphoric acid) and 8.2–5.9 (phosphogypsum).