Development of biodegradable spray mulch from lignosulfonate, chitosan, and biochar towards sustainable agriculture

Authors: KASERA, N - Auburn University; ADHIKARI, SUSHIL - Auburn University; JAHROMI, HOSSEIN - Auburn University

Submitted to: Sustainable Materials and Technologies
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/13/2026
Publication Date: 3/14/2026
Citation: Kasera, N., Adhikari, S., Jahromi, H. 2026. Development of biodegradable spray mulch from lignosulfonate, chitosan, and biochar towards sustainable agriculture. Sustainable Materials and Technologies. 48:e01960. https://doi.org/10.1016/j.susmat.2026.e01960.
DOI: https://doi.org/10.1016/j.susmat.2026.e01960

Interpretive Summary: Plastic polyethylene mulches are widely used in agriculture but generate persistent plastic residues and require labor-intensive retrieval after use. While biodegradable mulch films have been explored, most rely on precast films and do not adequately address practical application challenges. Sprayable biopolymer solutions that form protective films on soil surfaces offer an eco-friendly alternative to plastic-based mulches and align with sustainable agricultural practices. This work reports a fully biobased, spray-applied mulch system based on chitosan and lignosulfonate – both beneficial for soil health – that can form an in-situ protective layer on the soil surface. Results demonstrate a practical, spray-applied, and biodegradable alternative to conventional plastic mulches that integrate material design, application strategy, and end-of-life considerations.

Technical Abstract: Plastic polyethylene mulches are widely used in agriculture but generate persistent plastic residues and require labor-intensive retrieval after use. While biodegradable mulch films have been explored, most rely on precast films and do not adequately address practical application challenges. Sprayable biopolymer solutions that form protective films on soil surfaces offer an eco-friendly alternative to plastic-based mulches and align with sustainable agricultural practices. Therefore, in this work, we report a fully biobased, spray-applied mulch system based on chitosan and lignosulfonate – both beneficial for soil health – that can form an in-situ protective layer on the soil surface. Biochar (10%, 20%, and 30% of the lignosulfonate weight) was also incorporated to further tailor functional performance. The formulation is prepared via room-temperature aqueous processing, eliminating the need for film laying and post-harvest removal. Interactions between lignosulfonate and chitosan enable film formation, while biochar incorporation modulates mechanical behavior, optical properties, and degradation kinetics. The tensile strength of the lignosulfonate-chitosan films ranged from 0.82 to 6.22 MPa, with elongation at break ranging from 6.77% to 27.30%. Biochar addition to the composites increased flexibility and opacity and the composites effectively blocked UV radiation. The biopolymer formulation with biochar (20% of the lignosulfonate weight) was successfully spray-applied using a commercially available garden sprayer without observable nozzle clogging under the tested conditions, and reduced soil evaporation from 678 to 480 g m-2 day-1. Tested materials also showed rapid biodegradation, losing more than 40% of their weight during the first 10 days of the experiment. Together, these results demonstrate a practical, spray-applied, and biodegradable alternative to conventional plastic mulches that integrate material design, application strategy, and end-of-life considerations.