Mealworm Frass as a Sustainable Organic Fertilizer for Greenhouse Tomato Cultivation

Due to the environmental impact and increasing cost of inorganic fertilizers, farmers are exploring alternative fertilization strategies. Tenebrio molitor, otherwise known as the mealworm, is one of the most widely reared insect species for the production of high-quality protein for animals and humans. Mealworm frass (MF), a nutrient-rich byproduct of Tenebrio molitor cultivation, presents a viable option for organic fertilization. To investigate the fertilizer potential of frass, a greenhouse pot experiment was conducted, comparing three levels of MF (MF1, MF2, and MF3 at 20, 40, and 80 g/L soil, respectively), organic compost (ORG), and inorganic fertilizer (FERT). MF gave comparable results to FERT in terms of the measured parameters of vegetation, flowering, and production. ORG also gave comparable results to FERT as far as flowering and production but had significantly lower height compared to it. The MF3 treatment significantly improved the average fruit weight and total yield by 19.56% and 30.81%, respectively, compared to the ORG treatment. The two highest doses of MF outperformed FERT in terms of leaf and soil nutrient status, while MF1 and ORG did not differ from it. Furthermore, MF3 yielded 20% greater fruit weight than MF1. However, MF1 was comparable to FERT in fruit weight, resulting in superior fruit color. These results support reduced-input agriculture by providing data for optimizing soil fertility and nutrient management in crops. The findings of this experiment suggest that MF is a viable alternative to inorganic fertilizers and organic compost for greenhouse cultivation of tomatoes. These results highlight the potential of MF as a circular, bio-based fertilizer capable of maintaining tomato productivity while improving soil fertility under protected cultivation systems.