Formulation of versatile feeds to adjust the N:P:K ratio in aquaponics systems: performance and health of juvenile Nile tilapia (Oreochromis niloticus), and quality and quantity in lettuce biomass production

Author(s)

Stefano Francisco Pereira Duarte

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2023-02-06

Examining board members

Brunno da Silva Cerozi; Tamara Maria Gomes Aprilanti; Paulo Cesar Falanghe Carneiro

• Advisor: Brunno da Silva Cerozi

Abstract

Aquaponics is a system that integrates fish and plant production in a closed recirculating system, in which fish production wastes become bioavailable nutrients for plants that have a high nutrient removal capacity and thus water quality enhancement for fish. In aquaponic production systems, potassium is the nutrient that generally presents the greatest limitations, since the feeds supplied to the fish are formulated to meet their nutritional requirements and not to release nutrients that meet plant requirements. The objectives of this work were to determine the effectiveness of formulating versatile feeds for aquaponics containing increasing levels of potassium phosphate in a diet for fish on the quantity and quality of vegetable biomass produced from lettuce and to determine the effects on growth performance and changes in the hematological status of tilapia juveniles, were used. The trials for each potassium phosphate inclusion level were conducted and analyzed in a completely randomized design, with three treatments and three replications each (n=3) nine independent aquaponics systems. The tanks were populated with tilapia juveniles, which were fed twice a day at a rate of 3% of live weight, with three experimental diets formulated to meet the nutritional requirements of tilapia, containing the inclusion of 0 (T1), 50 ( T2), and 100% (T3) of potassium phosphate replacing dicalcium phosphate. The results of weight gain, feed conversion rate and specific growth rate showed significant differences among treatments, with T2 and T3 showing the best fish growth. For plants, T3 showed the highest production of fresh biomass. Treatments T2 and T3 showed higher values compared to T1 in terms of K and P uptake by plants. Water temperature and OD data were similar among all treatments. T1 showed a significant difference in the pH of the aquaponic solution compared to T3. T2 and T3 showed higher values of electrical conductivity throughout the experiment. The concentration of P and K in the water was higher for T2 and T3. T3 showed a N:P ratio 12.5 and 2.5 times higher than T1 and T2, respectively. The N:K ratio had T3 with the highest ratio (1.0:1.61). The K:P ratio presented T1 with the highest ratio (1.0:11.29), with T2 and T3 presenting values 5.40 and 7.19 times lower. No significant differences were observed in the hematological profile of fish fed with the different treatments. The versatile feeds showed promising results, improving the production of tilapia and lettuce biomass by adjusting the N:P:K ratio in aquaponics systems. (AU)

• FAPESP's process: 21/00936-2 - Formulation of versatile diets to adjust the N: P: K ratio in aquaponic nutrient solutions: performance and health of Nile tilapia (Oreochromis niloticus) juveniles, and quality and quantity of lettuce biomass production
• Grantee: Stefano Francisco Pereira Duarte
• Support Opportunities: Scholarships in Brazil - Master