The potential of double recirculating aquaponic systems for intensive tomato production

Aquaponics combine the production of fish and plants in a sustainable way due to the double use of water and nutrients. Compared to conventional single recirculation aquaponic systems (SRAPS), the double recirculation aquaponic systems (DRAPS) are improved by the combination of two separate recirculating systems: the recirculating aquaculture system (RAS) for fish rearing and a closed hydroponic cycle for plant production. Both systems are connected in one direction to transfer the nutrient rich fish waste water to the hydroponic unit. The unidirectional connection of both systems allows the optimisation of fish waste water for plant growth by addition of mineral fertilizer without negative effects on fish rearing. DRAPS is a relative new approach and information about the functionality and successful use are rare. Therefore, more research on DRAPS is necessary. The present study was focused on different growth and production parameters of tomatoes produced in DRAPS compared to those produced in conventional hydroponics. Investigations during an annual production in 2015 showed that tomatoes produced in DRAPS have a comparable plant growth and development as obtained for conventional hydroponics. Even the fruit quantity and the fruit quality, including nutrient contents, were similar in both production systems.