Synergistic Effects of Nano-Gypsum, Biochar, and Microbial inoculants on Salt Leaching and Soil Reclamation of Saline-Sodic Soils

To explore the potential of nanotechnology in soil reclamation and enhance gypsum efficiency for sustainable agriculture, we examined individual and combined treatments of nano-gypsum (NG), biochar, and microbial inoculants (Trichoderma harzianum and Pseudomonas fluorescens) for effective soil reclamation of saline-sodic soil. The experiment comprised nine treatments, with nano-gypsum (NG) applied at three levels, both alone and in combination with biochar and microbial inoculants, along with a conventional gypsum-based reference treatment (Control, GR). The treatments were incubated for 15, 30, and 45 days. Subsequently, a soil column leaching experiment was conducted to evaluate the synergistic effects of the different amendments on leachate and soil characteristics. Findings reveal that Treatment T9 (NG at 45% GR combined with biochar and microbial inoculants yielded a significant increase in leachate concentrations of Ca²⁺ (9.54%), Mg²⁺ (17.10%), Na⁺ (34.1%), and sodium adsorption ratio (35.01%) compared to GR as compared to individual treatment of biochar, microbial inoculants and NG. The increase in both Ca²⁺ and Na⁺ in the leachate indicates active dissolution and ion exchange, resulting in the release and removal of displaced Na⁺. Simultaneously, the combined amendments significantly reduce soil electrical conductivity, influencing the concentrations of Ca²⁺, Mg²⁺, and Na⁺ ions in the soil. An increase in cation exchange capacity accompanied the reduction in exchangeable sodium percentage and SAR, primarily attributed to biochar application, while nano-gypsum enhanced ion exchange processes through Ca²⁺ mediated Na⁺ displacement. This treatment was the most effective in reclaiming soil compared to the conventional gypsum treatment. The study highlights the potential for enhanced sodium-calcium balance in the soil, showcasing improved soil quality, mitigated salinity-related issues, and improved soil properties.