From waste to resource: evaluating leaf litter compost-derived bio-nutrient solutions for enhanced growth and nutrient-use efficiency of leafy vegetables under soilless culture

Soilless culture open systems rely heavily on synthetic fertilizers, creating environmental concerns and motivating the search for sustainable nutrient alternatives. This study evaluated four organic nutrient extraction methods – compost tea, aerobic degradation, anaerobic digestion, and combined anaerobic – aerobic degradation for spinach (Spinacia oleracea) cultivation under controlled conditions. Compost tea produced the greatest nutrient enrichment (electrical conductivity 7.04 dS/m), substantially exceeding the other extracts (1.79–2.37 dS/m). Compared with a conventional nutrient solution, the optimized organic formulation increased plant height by 27.5%, shoot biomass by 27.8%, root length (22.86 vs. 20.32 cm), and chlorophyll content (40.2 vs. 37.2). Nutrient uptake efficiencies reached 97% for nitrate-N and approximately 99% for phosphorus, potassium, and sulfur, while pH (6.84–7.60) and electrical conductivity remained stable throughout cultivation. These results demonstrate that the optimized organic nutrient solution can effectively replace synthetic fertilizers while improving plant growth and nutrient utilization under controlled conditions. Future research should evaluate its long-term performance, scalability, and economic feasibility across diverse crops and commercial greenhouse production systems.