Extension of Aquaponic Water Use for NFT Baby-Leaf Production: Mizuna and Rocket Salad

Abstract

Aquaponics is a recirculating technology that combines aquaculture with hydroponics. It allows nutrients from fish waste to feed plants and thus saves water and nutrients. However, there is a mismatch between the nutrients provided by the fish waste and plant needs. Because of this, some nutrients, notably N, tend to accumulate in the aquaponic water (APW or AP water). The aim of this study was to investigate how APW, which is depleted of P and K but still rich in N, could be further utilized. APW was used in a mesocosm and compared with APW from the same source that had been supplemented with macro-nutrients (complemented AP water or CAPW) and a hydroponic control (HC). Mizuna (M) and rocket salad (R) were used as short-cycle vegetable crops in a NFT system. The results revealed that the low production potential of APW was mainly caused by the lack of P and K. If these were supplemented, the yields were comparable to those in the HC. M yield in CAPW was significantly higher than that of HC, probably due to biostimulant effects connected to the organic components in the water as a result of fish farming. Water type, cultivation density, and intercropping significantly influenced the qualitative characteristics of the crop in terms of antioxidant compounds and minerals. Nitrate content in vegetables was lower than European regulation limits. The extended use of APW is viable if the missing nutrients are supplemented; this could be a strategy to increase the efficiency of water and nitrogen use, while further reducing environmental impact.

Effect of stocking density of fish on water quality and growth performance of European Carp and leafy vegetables in a low-tech aquaponic system

“…This aspect, as reported by several authors [3, 20, 21], reduced the effective nitrification of the ammonium produced by fish, thus slowing the N availability for the plant. During the experiment, after the full activation of the biofilter, the yield of crop, especially in the APL, was comparable or higher than the control due to the continuous supply of N compounds from the fish and probably also due to the accumulation of several humic-like and protein-like dissolved organic matter components in the water [22] that exert a biostimulant effect [23, 24]. Considering the yield values, the production of catalogna was lower (-60%) than that obtained in open-field conditions [25]; the production of lettuce, on the other hand, especially for HP and APL, is in line with that reported in other soilless experiments [26].…”

Lettuce growth in aquaponic system and in soil fertilized with fish sludge

“…Delaide et al (2016) demonstrated that aquaponics production with nutrient supplementation performed better than conventional aquaponics and hydroponics. Nicoletto et al (2018) found that aquaponics water lacks adequate levels of P and K to meet desirable yields of baby leaf greens, whereas supplementation with these nutrients showed better growth of the varieties when compared to conventional hydroponics. Estrada et al (2018) proposed the use of stochastic models for predicting and analysing the production of tilapia ( Oreochromis niloticus ) and lettuce cultivated in an aquaponic system.…”

Stochastic modelling of aquaponic production of tilapia (Oreochromis niloticus ) with lettuce (Lactuca sativa ) and cucumber (Cucumis sativus )

“…Schmautz et al () obtained significantly lower tomato production in NFT than in a floating raft system but not than medium‐based system (Maucieri et al, ). Nevertheless, NFT appears to be an appropriate technology for aquaponics, based on capital cost and ease of use (Goda, Essa, Hassaan, & Sharawy, ; Lennard & Leonard, ; Nicoletto et al, ).…”