A Study of Phosphorus and Calcium Dynamics in an Integrated Rainbow Trout and Spinach (Nores variety) Aquaponic System with Different Crop Densities

Abstract

The goal of this study is to quantify both calcium and phosphorus budgets for an integrated rainbow trout – spinach (Nores variety) aquaponic system, where three crops densities were used (BH1–59 crops/m2, BH2–48 crops/m2 and BH3–39 crops/m2 and a control variant). Fish were fed with two types of feed (41% and 50% protein), using 3 different feeding regimes. Total calcium and total phosphorus retention rates for each of the three tested spinach biomass densities were individually determined by water chemical and plant biochemical analysis. Also, the concentration of those two macroelements was determined from fish meat and fish faeces. Significant differences (p<0.05) were recorded between fish faeces total phosphorus content and between total calcium and total phosphorus retention rates for each of the three variants of tested crops densities (significant higher at BH1 compared to BH3, p<0.05). It is recommended that lower densities to be used for a better crop absorption of both calcium and phosphorus or a lower hydraulic flow regime and a better light intensity to be applied in case of the used integrated aquaponic system.

Keywords

• aquaponic system
• calcium
• faeces
• phosphorus
• rainbow trout
• spinach