This study explored a sustainable approach to agricultural waste management by converting spoiled eggs into high-quality liquid fertilizers. Egg-based fertilizers (EFs) produced from different input compositions were characterized for their physicochemical properties, and the most suitable EF was further evaluated for its effects on the growth, physiological performance, and yield of Malabar spinach (Basella alba). Three treatments were prepared: EF1 (spoiled eggs without chicks), EF2 (spoiled eggs with chicks), and EF3 (a 1:1 mixture of both). EF1 contained the highest levels of total nitrogen (6.09 g L-1), total and available phosphorus (1.05 and 0.80 g L-1 P₂O₅, respectively), and total calcium (3.79 g L-1 CaO), with no detectable Escherichia coli or Salmonella. EF3 exhibited the highest potassium content (1.16 g L-1 total and 1.04 g L-1 available K₂O). In a field trial, EF1 was applied at 1.0%, 1.5%, and 2.0%, and compared with a commercial organic fish fertilizer and an unfertilized control. Applications of EF1 at 1.5% significantly enhanced shoot length, leaf dimensions, SPAD, leaf area index (LAI), and yield (6.3 and 11.9 t ha-1 at 21 and 37 days after planting, respectively). Yield showed strong positive correlations with leaf length (r = 0.96**), leaf width (r = 0.92**), SPAD (r = 0.84**), and LAI (r = 0.90**), supporting the observed treatment effects. Nitrate concentrations in all the treatments remained below 150 mg kg-1, within safe limits for leafy vegetables. Overall, EF1 at 1.5% represents a safe, effective, and sustainable fertilization option for Malabar spinach production.
