Complementary Nutrients in Decoupled Aquaponics Enhance Basil Performance

Dylan Rodgers,Neil Mattson,Michael B. Timmons,Eugene Won

doi:10.3390/horticulturae8020111

Dylan Rodgers, Neil Mattson + Show 2 more

Open Access

https://doi.org/10.3390/horticulturae8020111

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Abstract

Aquaponics combines raising fish and growing plants by recycling water and nutrients to reduce water consumption and reliance on chemical fertilizers. Coupled aquaponics systems recirculate water between fish and plant crops, whereas decoupled systems send mineralized fish effluent and wastewater unidirectionally to an independent hydroponic loop. Decoupling enables changes to the water, such as pH adjustments and complementary nutrient additions, to promote plant performance. In this study, basil, Ocimum basilicum (L.), was transplanted into 4 L containers filled with decoupled aquaponic (DAP), nutrient-complemented decoupled aquaponic (DAP+), or chemical-based conventional hydroponic (CON) nutrient solutions and grown for 21 days at pH 5.8. Plants grown in DAP+ and CON had greater biomass, height, and Soil Plant Analysis Development (SPAD) chlorophyll index and lower root:shoot biomass ratios than those in DAP. Shoot fresh and dry biomass was 11% greater for CON than DAP+, while height, SPAD chlorophyll index, and root:shoot ratio did not differ. We concluded that added nutrients in DAP+ enhanced performance compared to DAP, and the biologically derived nutrition in DAP+ enhanced performance to be similar, but not equal, to CON. We cannot recommend specific adjustments to the targeted blend of complementary nutrients tested, but findings suggest that complementary nutrients are effective in decoupled aquaponics.

Highlights

IntroductionAquaponics integrates recirculating aquaculture (raising fish) and hydroponics (growing plants without soil)
This study aimed to evaluate the effect of complementary nutrients on basil performance in decoupled aquaponics compared to conventional hydroponics
Mean shoot fresh biomass for conventional hydroponic (CON) was 11% greater than for decoupled aquaponic (DAP)+

Summary

Introduction

Aquaponics integrates recirculating aquaculture (raising fish) and hydroponics (growing plants without soil). Nutrients from recirculating aquaculture are recycled as fertilizer for the plants, and the plants, in turn, clean the water through uptake of nutrients [1]. Aquaponics systems can produce two food crops with less water, chemical fertilizer, and environmental nutrient runoff than other common food animal and plant production systems [2]. Land-based recirculating aquaculture systems (RAS) and hydroponics can each reduce water use by 90% or more compared to some conventional aquaculture or field-based agriculture systems [3,4]. Deriving plant nutrition aquaponically can reduce the reliance on chemical fertilizers such as nitrate, potassium and phosphorus, which are usually mined or created with fossil fuel-intensive processes [5]. Aquaponics can repurpose aquaculture waste as a more environmentally sustainable alternative to some chemical fertilizers

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