Valorization of spent mushroom substrate and cassava pulp into biodegradable nursery pots: mechanical performance, cultivation performance, and biodegradation behavior

This study investigated the valorization of spent mushroom substrate (SMS), vermicompost, and cassava pulp into biodegradable nursery pots as alternatives to plastic containers. The three residues were functionally integrated as lignocellulosic reinforcement, a porosity-modifying component, and a starch-based binder, an approach not previously reported for this residue combination, to balance mechanical performance and deterioration within a single formulation. Seven SMS:Ver:Cas formulations were evaluated for compressive strength, bulk density, porosity, water holding capacity, cultivation deterioration, and microstructural changes. Material composition significantly influenced structural and deterioration behavior. The 3:3:4 formulation exhibited the highest compressive strength (165.02 ± 11.43 kPa) and lowest porosity (13.50%), reflecting improved particle packing and interfacial bonding among the three components. Bulk density, porosity, and water holding capacity ranged from 0.24–0.45 g/cm³, 13.50–42.50%, and 132.60–219.87%. Higher vermicompost increased porosity and deterioration; SMS-rich formulations remained more stable. Cultivation with Ipomoea aquatica over 8 weeks revealed progressive cracking, matrix softening, fiber debonding, and root penetration through the pot walls. Deterioration was assessed qualitatively, so quantitative biodegradation kinetics were not determined. A preliminary cradle-to-gate life cycle assessment indicated approximately 80% lower global warming potential than a conventional polypropylene pot; as end-of-life processes and other impact categories were excluded, this is a preliminary indicator rather than a comprehensive evaluation. These findings demonstrate that the complementary functions of SMS, cassava pulp, and vermicompost can be tailored to balance mechanical stability and deterioration during cultivation, with preliminary evidence of reduced environmental impact.