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This study evaluated the combined effects of elemental sulfur (ES) and synthetic organic conditioner (SOC) amendments on the chemical properties of calcareous soils from arid and semiarid regions. A 60-day laboratory incubation experiment was conducted to determine if Mending ES-treated soils with SOCs would improve selected chemical properties such as pH and soluble and extractable nutrients. Four calcareous soils from central Saudi Arabia varying in CaCO3 content were used. Air-dried soil samples were treated with (I) ES at rates of 7.7, 14.8, 23.7, and 19.0 g kg(-1) to neutralize 50% CaCO3 content of soil I, soil 2, soil 3, and soil 4, respectively; (2) four SOCs-Broadleaf(BL), Aquasorb (AS), Agrihope (AH), and Hydrogel (HG)-at a rate of 0.2% (dry weight basis). The addition of ES or ES + individual SOC amendments improved some of the soil chemical properties. In all cases, addition-of ES + SOC was more effective than ES alone as determined by a decrease in soil pH and an increase in soluble SO42- and Na+, as well as extractable Fe and Mn. Addition of ES alone was more effective than ES + SOC only in increasing soluble Ca2+ and Mg2+, In contrast, the addition of an individual SOC adversely affected soil properties resulting in an increase in soil pH and soluble Na+ and decreases in soluble Ca2+ and Mg2+ and extractable Zn, Fe, and Mn. Extractable Cu and P were not affected by the changes in soils chemistry induced by the treatments. Soluble K concentrations were significantly high in all sail samples treated with the HG conditioner and ES + HG. The deleterious effects by individual SOC on selected soil chemical properties indicates the potential adverse effect by these conditioners on calcareous soils. Nevertheless, the addition of ES in conjunction with SOC was generally synergistic and improved soil properties.