Agri Kultuur March/ Maart 2016 - Page 22

Article and photos by Henk Stander Aquaculture Division, Department of Animal Sciences, University of Stellenbosch A quaponic systems are bio-integrated recirculating aquaculture systems that incorporate the production of plants without soil. Vegetables, fruit, flowers, and/or herbs can be produced in this kind of production systems. Aquaponics has become increasingly popular on different levels. A very active WhatsApp aquaponics group was established after the Murray Hallam Aquaponic Master Class short course in Stellenbosch last year. Group members interact with each other on a daily basis and share information. To make a success out of your aquaponic system one needs to follow a hands-on approach and manage your system by paying attention to technical, biological and scientific detail when monitoring the system on a daily basis. Aquaponic systems offer several advantages. In Recirculating Aquaculture Systems effluent is discharged from the system to eliminate organic sediment and prevent nutrient build-up. In aquaponic systems, the plants recover a substantial percentage of these nutrients, thereby reducing the need to discharge water to the environment and therefore extending water use, i.e., by removing dissolved nutrients through plant uptake, the water exchange rate can be reduced. The nitrate accumulation in culture waters can be reduced to as much as 97% in the aquaponic system when compared with the fish-only system. Economics: The economics of aquaponic systems depend on specific site conditions, production decisions taken and markets. It would be inaccurate to make sweeping generalizations because material cost, construction cost, operating costs and market prices vary by location. However, the profit margins will definitely be higher if the product manufacturing costs are low and the food distribution supply chain is short. The transportation, packaging and conservation of the food are time and energy consuming, which has an effect on the additional costs and freshness of the product. In order to meet these challenges, more urban and peri-urban fresh food production plants need to be implemented to guarantee efficient short food supply chains. Dr. James Rakocy showed with respect to the crop choice, leafy greens generally achieve a higher profitability than fruity vegetables. In an initial economic analysis, given the University of Virgin Islands (UVI) system design, they had a profit margin with basil exceeding almost by a factor 4 of that of lettuce. This finding