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