Hydrochar Utilization for Saline-Alkali Soil Amelioration and Its Carbon Sequestration Potential Assessment

For the current situation of saline-alkali soil amelioration, it is urgent to explore a multi-objective amelioration strategy involving crop income increase and environmental benefits. This study used pine-needle hydrochar to ameliorate saline-alkali soil and conducted column and pot experiments to investigate its effects on soil properties and crop growth. And the environmental advantages of hydrochar are evaluated through Life Cycle Assessment (LCA). The electrical conductivity, exchangeable sodium percentage, and pH of saline-alkali soil ameliorated with hydrochar using the column elution method are reduced by 60%, 58%, and 1.2 pH units, respectively, compared to the original soil. Also, the gene copy number of the ameliorated soil has doubled according to qPCR determination. Pot experiment results show that the root length, fresh weight, and germination rate of wheatgrass are increased by 107, 75, and 20%, respectively. These results demonstrated that the exchange of Na⁺ with H⁺ released from hydrochar reduced the soil alkalinity and the viability of organisms is enhanced. Moreover, based on this study's data including the hydrochar dosage and wheatgrass yield, the LCA results showed 3.7 × 10⁹ t CO₂e carbon sequestration potential and significant environmental benefits.