A Comparative Study of Two Aquaponic Methods: Raft vs. Gravel Filtration

Sweet basil (Ocimum basilicum) was planted and grown using both a gravel filtration and floating raft method in order to determine which produced the greatest biomass. Basil was also grown under the same conditions in soil as a control. The growth period was 30 days at which point the total biomass was measured and weighed (wet weight). The gravel filtration method produced the greatest biomass according to height (19in), and weight (459 gms). The basil grew twice as fast in the soilless system compared to the control group (P = 0.0049). Comparing only the two aquaponic methods, the gravel filtration method of aquaponics was significantly superior to the raft method when growing the herb basil (P = 0.0014). Introduction Soilless agriculture, or hydroponics, entails growing vegetation without a substrate, using chemical fertilizers (Emberger 1991). Aquaculture is the captive cultivation of aquatic organisms for human use (Howerton 2001). The combination of both practices creates a third system of soilless cultivation known as aquaponics. This system differs from hydroponics and aquaculture in that fish are grown simultaneously in the same water as the vegetation resulting in byproducts (nutrients from fish wastes) that fertilize the plants instead of chemical additives. Aquaponics creates a mutualistic relationship between fish and plants; the fish produce nutrients metabolically which the plants absorb, cleaning the water in the process. Growth continues until both fish and plants are harvested as food products (Whitton 2009). Some of the advantages of aquaponics are: control of nutrition, high yields on a s footprint, lower costs due to recirculating water, and easy management of disease mall and pests 1994).