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Example of a healty
hydroponic tomato garden (note the small root
pots) |
Hydroponic
vegetables grown with no
soil |
Hydroponics and Fish Farming Combined (Aquaponics)
Hydroponic
growers view fish-manured irrigation water as a source of organic
fertilizer that enables plants to grow well. Fish farmers view
hydroponics as a biofiltration method to facilitate intensive
recirculating
aquaculture. Greenhouse growers view aquaponics as a way to
introduce organic hydroponic produce into the market place, since
the only fertility input is fish feed and all of the nutrients
pass through a biological process. Food-producing greenhouses -
yielding two products from one production unit - are naturally
appealing for niche marketing and green labeling. In arid
regions
where water is scarce, aquaponics is an appropriate technology that
allows food production with re-used water Aquaponics is a working
model of sustainable food production wherein plant and
animal agriculture are integrated, and recycling of nutrients and
water filtration are linked.
In addition to commercial application, aquaponics has become
a popular training aid on integrated bio-systems
with vocational agriculture programs and high school biology
classes.
Zero Waste Theory
Instead
of locating the fish and vegetable components in separate containers
inside a greenhouse,
fish production can be located in outdoor tanks or adjacent
buildings. The effluent simply
needs to be delivered to hydroponic vegetable beds. In warm climates, hydroponic
vegetable
beds may be located outside. As an example, the Center for
Regenerative Studies at California
State Polytechnic University-Pomona implemented an outdoor
integrated bio-system that
links: (a) a pond containing treated sewage wastewater stocked with
tilapia and carp; (b) water
hyacinth - an aquatic plant very efficient at sucking up nutrients -
covering 50% of the water
surface area; the plant biomass generated by water hyacinth is used
as feedstock for compost
heaps; (c) nearby vegetable gardens irrigated with nutrient-laden
pond water.
In
addition to locating the fish and vegetable components in separate
containers, fish and plants can
be placed in the same container to function as a polyculture. For
example, plants sit on top of
floating polystyrene panels with their roots hanging down into the
water that fish swim around
in. Models include the Rackocy system, solar-algae ponds (see
literature by Zweig and Kleinholz),
and the solar-aquatic ponds, or Living Machines, made popular by
John Todd at Ocean
Arks International.
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