Challenges and opportunities in using biowaste for sustainable hydroponic netted melon (Cucumis melo L.) cultivation

CONTEXT: Circular agriculture aims to promote resource recycling for a sustainable environment. Substituting chemical inputs with biowaste alternatives is a practical strategy for fostering sustainable agriculture, especially in hydroponic systems that enable efficient production under resource-limited conditions. Netted melons (Cucumis melo L.) are high-economic-valued crops, which represents an opportunity to explore these substitutions. However, using biowaste in hydroponics requires additional pretreatment processes and may lead to lower fruit weights, impacting both environmental and economic outcomes. OBJECTIVE: This study aimed to evaluate the environmental impacts of partially substituting conventional fertilizers with biowaste fertilizers in hydroponic melon cultivation. METHODS: This study performed a life cycle assessment (LCA) to assess the effects of substituting 20 % biowaste (mealworm frass) for conventional fertilizers (synthetic chemicals) in hydroponic netted melon cultivation. The practical trials were first carried out to measure the impacts of biowaste substitution on plant growth and crop yields. Then, scaled-up analyses were conducted to include seasonal variability in this study. RESULTS AND CONCLUSIONS: Biowaste Substitution for conventional fertilizers in hydroponic netted melon cultivation increased the total environmental impacts by 11.3–13.7 %. This increase was primarily attributed to additional energy requirements for biowaste pretreatment and reduced fruit weight, leading to a 2.1 % rise in greenhouse gas (GHG) emissions. In particular, although biowaste substitution reduced mineral source scarcity by 20.0–30.7 %, the global warming potential increased by 11.6–14.2 %. Also, we initially expected to reduce GHG emissions by 8.2 % when implementing biowaste substitution, but additional energy requirements and reduced fruit weights offset the benefits. SIGNIFICANCE: This study highlights both the potential and challenges of biowaste substitution in hydroponic systems. This illustrated the unstable conditions in soilless cultivation when applying biowaste fertilizers. As hydroponic farming continues to advance within circular agricultural systems, careful consideration is required for food productivity and energy requirements to achieve environmental sustainability in agriculture systems.