Carbon and nitrogen cycles supported by microbes: a case study of organic aquaponics

Aquaponics, as an alternative solution for food production, has the potential to provide solutions in areas with limited water resources.
This study evaluated food productivity and environmental impacts of small-scale, resource-recycled aquaponics to minimize water and nutrient inputs while reducing greenhouse gas (GHGs) emissions.
The experimental aquaponics unit, consisting of a 5 m² vegetable cultivation space associated with a 350-L fish tank, yielded 9.8 kg of plants and 5.6 kg of fish over six months.
The closed-water system demonstrated the potential for minimizing water inputs by utilizing a 200-W dehumidifier to collect water from humidity.
The ecosystem within the unit achieved a balance of nitrogen and carbon, which were partially used by non-target diatom, algae, and microbes in the unit.
Bacterial biodiversity was significantly changed during the plant and fish cultivation.
Nitrogen-fixing bacteria were identified in the rhizosphere and the circulated water, including Cyanobacteria and Rhizobium groups, suggesting their potential contributions to crop growth.
The organic aquaponics system’s annual carbon footprint (CFP) was estimated at 59 kg CO₂ eq kg^‑1 using the carbon and nitrogen analysis data and available factors.
These findings support the potential of closed-water, small-scale organic aquaponics in arid regions to enhance food security, improve nutrition, and reduce greenhouse gas emissions.
This system can also minimize the use of limited water resources and promote sustainable food production in households.

International Symposium on Models for Plant Growth, Environments, Farm Management in Orchards and Protected Cultivation – HorchiModel2023

S. Teramoto

closed-water system, carbon footprint (CFP), microbial biodiversity, nitrogen-fixing potential, food production, arid regions

https://doi.org/10.17660/ActaHortic.2025.1425.60