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The growing global demand for sustainable vegetable production has accelerated the adoption of hydroponic systems, which can reduce water use by up to 90% compared with conventional soil-based agriculture while enabling year-round cultivation. However, conventional hydroponics depends heavily on mineral fertilizers derived from finite resources, raising concerns about long-term sustainability. Organic hydroponics has emerged as a promising alternative by substituting synthetic fertilizers with bio-based inputs such as compost teas, fish hydrolyzates, and digestates, while integrating microbial processes that enhance nutrient cycling and plant growth. This review synthesizes current knowledge on organic nutrient dynamics in hydroponic vegetable systems, with emphasis on nutrient solution formulation, bioavailability, and crop uptake efficiency. Microbial communities are highlighted as crucial mediators of mineralization, nutrient-use efficiency, and pathogen suppression, although their functional roles remain insufficiently characterized. Resource-oriented strategies such as water quality management, recycling of spent nutrient solutions, and valorization of waste streams through composting, vermicomposting, anaerobic digestion, and nutrient recovery technologies are assessed as key enablers of circular agriculture. Key challenges include balancing nutrient release with plant demand, stabilizing organic solutions, maintaining food safety, and harmonizing policy and certification frameworks. Integrating standardized formulations, microbial innovations, and waste recovery can advance sustainable intensification, resilience, and food security.
Awad-Allah et al. (Mon,) studied this question.
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