Study on the effect of hydrothermal charcoal source modifier on saline-alkaline soil improvement

Land salinization has become a global issue. To mitigate this issue, the modifiers and water-soluble fertilizers have emerged as a promising strategy to enhance soil nutrient content and promote crop production in saline soils. In this study, based on the hydrothermal method for preparing corn stalks derived biochar prepared modifiers and water-soluble fertilizers for using in soda saline-alkali soil. Through field microplot experiments, the separate and interactive effects of different concentrations of them were studied, as well as their influence on the growth of alfalfa and Leymus chinensis on saline-alkali soil. The combined application of modifiers and water-soluble fertilizers can effectively increase soil nutrient content and enzyme activity, significantly reducing soil pH and alkalinity. It was found that the optimal application rate of 20 g/kg of improver resulted in a 4.99% decrease in pH of soil and 11.23% decrease in alkalinity. Additionally, organic matter, available P2O5, NH4+-N, and NO3--N contents increased by 25.74%, 28.48%, 19.87%, and 32.90%, respectively. Soil enzyme activities generally peaked at 20 g/kg of modifiers and water-soluble fertilizers, with sucrase showing the most significant increases, with 31.14% for alfalfa and 25.52% for L. chinensis. Two-way ANOVA results demonstrated significant interaction effects between the modifiers and water-soluble fertilizer on pH, Ca2+ and Mg2+ content, quick-acting potassium content, soil sucrase and urease activity, biomass of soil and alfalfa leaf width. Moreover, planting alfalfa and L. chinensis indicated that combined use of modifies and fertilizer had a significant effect on promoting crop cultivation in saline-alkali soil. Our findings provided a robust theoretical groundwork for improving the management of saline soils and optimizing crop production in such challenging environments.