Multiple cross-linking induced lignin-based liquid mulch film for soil stabilization and crop growth promotion

Objective In response to white pollution and microplastic risks associated with the widespread use of polyethylene (PE) film in arid and semi-arid regions of China, this study proposes a novel strategy for preparing liquid films through non-covalent bonding self-assembly, guided by the goal of enhancing the utilization value of biomass resources. The aim is to develop green, biobased soil-covering materials and provide a sustainable alternative to PE film for cultivated land conservation in arid and semi-arid areas.

Method A ternary composite sprayable, multi-crosslinked lignin-based liquid film (LCP) was prepared using sodium lignosulfonate, chitosan, and polyvinyl alcohol as raw materials, with the mass ratio of chitosan to polyvinyl alcohol systematically adjusted. The physicochemical structure of the LCP was characterized using Fourier transform infrared spectroscopy, isothermal titration calorimetry, and rotational rheology. Mechanical properties were evaluated using a universal testing machine. The optimal formulation ratio and application rate of LCP were determined based on assessments of water vapor permeability, crop growth characteristics, and soil water retention capacity.

Result The synthesis of LCP is primarily driven by hydrogen bonding and electrostatic interactions, and the material exhibits pronounced shear-thinning behavior. When the mass ratio of sodium lignosulfonate, chitosan, and polyvinyl alcohol is 10∶4∶4, the resulting LCP demonstrates optimal performance, achieving a mechanical strength of 24.05 MPa, a water vapor permeability of 352.10 g/(m²·d), a seed germination rate of 95%, and an average root length of 19.44 mm. Compared with the untreated control, application at a dry matter dosage of 8.0 g/m² increases crop emergence rate, plant height, and total biomass by 54.55%, 26.90%, and 54.99%, respectively, while also significantly enhancing soil retention.

Conclusion The liquid mulch film developed in this study effectively promotes crop growth and enhances soil water retention capacity, offering a valuable strategy for reducing polyethylene (PE) film usage and enabling high-value utilization of agricultural and forestry wastes, with broad application prospects.