Elemental sulfur effects on salt leaching, plant growth, nutrient uptake, and microbial diversity in an arid saline soil

The amendment of salt-affected soils with elemental sulfur (S⁰) has been recognized for its potential to effectively reduce soil salinity and pH, thereby enhancing soil physicochemical properties, promoting crop growth, and improving yields. Despite these known benefits, the widespread adoption of S⁰ for managing saline soils, particularly in arid calcareous regions, remains limited. Consequently, this study aimed to evaluate the impact of S⁰ on salt leaching, soil pH, nutrient uptake, plant growth, microbial diversity, and community structure under alkaline saline soil conditions. The study includes three main experiments: a preliminary column experiment without plants, a field trial with Rhodes grass (Chloris gayana), and a greenhouse pot experiment with wheat (Triticum spp.). Our findings demonstrated that S⁰ incorporation into the soil exerted a positive influence, resulting in increased salt removal, reduced soil pH, and improved plant growth. Specifically, soil amendment with 750 kg S⁰ ha⁻¹ led to a substantial salt removal, exceeding double in the column experiment, approximately 91.3 % in the field trial, and about 34.1 % in the greenhouse pot experiment compared to the control. S⁰ amendment also significantly lowered soil and leachate pH in both field and greenhouse trials, with reductions of 3.3 % and 6.3 %, and 8.1 % and 4.4 %, respectively, relative to the control. Calcium and phosphorus uptake by Rhodes grass increased significantly by 75 % and 14 %, respectively, compared with the control. Soil organic matter content significantly increased from 0.6 % to 1.5 % compared to that of the control. This overall enhancement in soil conditions resulted in a considerable increase in Rhodes grass and wheat yields by 13 % and 59 %, respectively. While the prokaryotic diversity (16S V4 rRNA sequencing) in the Rhodes grass field trial was not significantly affected by S⁰ amendments after two months, the microbial community composition showed remarkable differences between the S⁰-amended and control samples. Eighty-three unique taxa were exclusively found in the S⁰-amended samples. In conclusion, our findings suggest that the amendment of soil with S⁰ is a promising strategy for the sustainable management of calcareous salt-affected soils in arid regions.