Lignosulfonate Improves Soil Fertility by Promoting Exchangeable Al³⁺ Immobilization and Facilitating Its Interaction with Soil Enzymes through Active Functional Group Surfaces

Soil acidification threatens soil health and sustainable agriculture, and conventional mitigation strategies have various limitations, underscoring the need for the creation of more effective and sustainable alternatives. In this study, we evaluated the effects of calcium lignosulfonate (CL) on the physicochemical properties of acidic soils (Rs, K₂j, and J₂s) through pot experiments. Additionally, molecular modeling calculations were employed to investigate the interaction mechanisms between CL and soil exchangeable acidity and active enzyme. The results showed that CL was superior to lime in reducing phytotoxic exchangeable Al³⁺, enhancing soil acidification buffering capacity, and improving soil fertility and plant biomass accumulation. These benefits were attributed to the strong competitive adsorption of exchangeable Al³⁺ by the CL surface active functional groups, enhanced interactions between CL and soil enzymes, and the restructuring of microbial communities. These findings provide valuable insights for developing efficient soil amendments to mitigate the effects of acidification, ultimately enhancing soil health and agricultural productivity.