Enhancing plant growth in aquaponic systems via potassium manipulation in fish feeds: A pilot study of tailored feeds bridging nutritional gaps in aquaponics

Autor(es)

Duarte, Stefano Francisco Pereira ; Cerozi, Brunno Silva

• Tipo de documento: Artigo Científico
• Fonte: AGRICULTURAL SYSTEMS; v. 218, p. 6-pg., 2024-05-15.

Resumo

CONTEXT: Aquaponic systems often face challenges with limited potassium availability in comparison to nitrogen and phosphorus required for proper plant growth. The formulation of commercially available fish feeds, expectedly, prioritize meeting fish nutritional requirements, but inadvertently neglect the critical nutrient needs of plants when used in aquaponic systems, resulting in imbalances between nitrogen, phosphorus, and potassium. In response to this issue, aquaponic practitioners have long sought the development of specific fish feeds that can provide a balanced ratio of nutrients required for proper plant growth. OBJECTIVE: This study aimed to investigate the efficacy of potassium -rich feeds formulated to increase potassium levels via strategic ingredient swaps without affecting the core feed formulation. The increased availability of potassium in the aquaponic system may stimulate essential physiological processes in plants, such as photosynthesis and nutrient uptake, leading to improved growth. Specifically, we hypothesized that operating aquaponic systems with potassium -rich feeds would result in increased plant biomass production without adversely affecting fish growth performance or hematological parameters. METHODS: Nine independent aquaponic systems were employed to rear tilapia juveniles integrated with hydroponic lettuce production, with three distinct experimental diets. These diets gradually replaced dicalcium phosphate with increasing amounts of potassium phosphate (control treatment: 100% dicalcium phosphate and calcium carbonate and 0% potassium phosphate and calcium chloride; 50%-MKP: 50% dicalcium phosphate, and calcium carbonate and 50% potassium phosphate and calcium chloride; and 100%-MKP: 0% dicalcium phosphate and calcium carbonate, and 100% potassium phosphate and calcium chloride), while maintaining consistent levels of crude protein, digestible energy and phosphorus. Fish growth and health, plant biomass and nutrient accumulation, and water chemistry parameters were assessed. RESULTS AND CONCLUSIONS: Hematological parameters among the fish did not significantly differ across the treatment groups. Fish feeding the tailored feeds exhibited enhanced weight gain compared to the control group. Notably, plants in systems receiving tailored feeds demonstrated improved growth. Elevated concentrations of potassium in treatments receiving tailored feeds supported increased nutrient availability and plant growth. The study highlights the efficacy of tailored aquaponic feeds in optimizing plant nutrition without causing adverse effects on fish growth and health. SIGNIFICANCE: Tailored aquaponic feeds addressing nutrient imbalances offer a promising approach to enhancing vegetable biomass production and overall system performance in aquaponic setups. By takling inherent nutrient deficiencies of conventional fish feeds, such approach presents a viable strategy to improve plant nutrition within aquaponic production systems. (AU)

• Processo FAPESP: 21/00936-2 - Formulação de rações versáteis para ajuste da relação N:P:K em sistemas de aquaponia: desempenho e higidez de juvenis de tilápia do Nilo (Oreochromis niloticus), e qualidade e quantidade na produção de biomassa de alface
• Beneficiário: Stefano Francisco Pereira Duarte
• Modalidade de apoio: Bolsas no Brasil - Mestrado
• Processo FAPESP: 17/14269-2 - Protocolo para a modelagem da dinâmica de nutrientes em sistemas de aquaponia através de análise de balanço de massa
• Beneficiário: Brunno da Silva Cerozi
• Modalidade de apoio: Auxílio à Pesquisa - Jovens Pesquisadores