Modeling the nitrogen uptake to balance lettuce and carp growth in an aquaponic system.
MSc-thesis abstract (submitted 19 February 2015 ):
Aquaponics might be considered a recently (re)discovered production technique. Currently few are the scientific studies about aquaponics. LEPAS (‘LEttuce Production in Aquaponic Systems’) is a model designed to predict lettuce and fish growth in aquaponic systems.
To calibrate and test LEPAS, lettuce plants (Lactuca sativa ‘Appia’) were grown in a small scale aquaponic system in combination with common carps (Cyprinus carpio). Plants were constantly harvested to measure the fresh weight, dry weight and leaf area. Fish were weighted just at the start and at the end of the experiment. The experiment was divided in two sub experiments: the first month a ratio of 1.1 kg of fish/m2 area covered by plant was applied, while the second month a ratio of 3.3 kg of fish/m2 area covered by plant. The model predictions for the plant dry weight resulted to be in good agreement with the observed values (R2=0.82), so as the fish growth prediction. LEPAS shows that the response of nitrate accumulation in the water is highly influenced by the fish/plant ratio. Therefore when using this tool for aquaponic systems’ scaling purposes it is advisable to focus on the nitrogen balance rather than on plant and fish growth response directly.