Sizing lettuce growing surface in aquaponic systems based on evapotranspiration and phosphorus fish feed

Due to the lack of healthy soils and water in the cities, there is a need of implementing more efficient production techniques such as aquaponics, which provides benefits of generating protein from aquatic species in addition to vegetables.
It makes efficient water and energy use.
The objective of this study was the estimation of the optimal lettuce growing surface, depending on the amount of phosphorus generated by the fish and taken into account the evapotranspiration.
The experiment was carried out in a greenhouse located at the Universidad Autónoma de Chapingo, from October 24 to November 28, 2022. A functional aquaponic units (2 m²) were installed with three repetitions, each aquaponic unit consisted of a 0.72 m² (103×70 cm) plant growing surface, 150-L tilapia pond.
Each pond has 16 tilapias with an initial average weight of 158.91 g.
The systems were one week without plants, for the maturation of each treatment, later on October 31, the transplant of the lettuce (Lactuca sativa L.) was carried out.
The fish tanks were oxygenated by means of a 370 W air pump, the temperature was maintained with a 100 W submersible resistance and the water was recirculated at a flow of 2.14 L min^‑1. Five weekly samplings were carried out in the nutrient solution, fish pond and biofilter to determine the phosphorus in the system. 2.58% of the total water in the system was added per day in the fish tank.
A daily fish feeding was recorded, also the average phosphorus found for the three repetitions in the fish tank increased from 6.7 mg L^‑1 (October 31, 2022) to 9.6 mg L^‑1 (November 28, 2022). The optimal growing lettuce area based on the phosphorus requirement by the plant was 0.95 m². This means that the actual lettuce growing surface can be increased by 32%. The results can be used as the starting point for the design of aquaponic systems in cities.

International Symposium on New Technologies for Sustainable Greenhouse Systems: GreenSys2023

R. Salazar-Moreno, A.C. Sánchez-Martínez, J. Pineda-Pineda, I.L. López-Cruz, E. Fitz-Rodríguez

tilapia, phosphorus, Lactuca sativa, water

https://doi.org/10.17660/ActaHortic.2025.1426.35