Development of Liquid Organic Fertilizers Using Agro-Industrial Wastes for the Hydroponic Cultivation of Lettuce
摘要
The study aims to develop a sustainable approach to enhance crop yield by integrating the utilization of agro-industrial residues with the advanced agricultural technique of hydroponics. Agro-industrial wastes such as paddy straw, wheat straw, molasses and biogas slurry, along with treated sewage water as diluent, were used for the fermentative production of liquid organic fertilizers (LOFs). The leachate recovered from 30-day fermented slurry contained acceptable levels of total N (868.6–1274.5 mg/L), P (273.2–500.8 mg/L), K (1082.4–1508.7 mg/L) and essential micronutrients. Nitrogen (1274.5 mg/L) and P (500.8 mg/L) were found maximum in leachate of S-LF1, while K level was highest in leachate of S-LF2 (1508.7 mg/L). Overall, heavy metals concentration was below 2.1 mg/L in leachate of six LOFs. Consequently, nutrients level in LOFs were suitable for the cultivation of green oak-leaf lettuce in deep-water culture hydroponics. The LOFs prepared using wheat straw and sewage water were more effective in enhancing plant growth and yield compared to paddy straw and distilled water-based counterparts, respectively. Green oak-leaf lettuce grown with S-LF1 showed comparable plant growth to those supplied with a standard inorganic solution, with maximum fresh shoot weight (43.85 g), dry shoot weight (4.03 g), leaf area (110.87cm2) and root length (33.07 cm). The results suggested that agro-industrial residues can be effectively repurposed to produce LOFs, capable of supporting lettuce growth in hydroponics. The study fulfils the dual purpose of recycling agricultural waste while improving nutrient efficiency and crop quality. This approach reduces environmental pollution and promote circular economy practices, aligning with the principles of modern yet sustainable agriculture.