Hydroponic Tomato
Growing
T
here are 3 hydroponic growing systems
suitable for the hydroponic growing of
tomato plants. Initially, the ebb-and-
flow method (or modifications of the
technique) was the method in use from the
late 1930s into the 1970s. In the mid-1970s,
Allan Cooper introduced his nutrient film
technique (NFT) that substantially changed
the basic concept of hydroponic growing,
eliminating the need of a rooting medium,
with the plant roots being periodically bathed
in a flow of nutrient solution.
With the introduction of drip irrigation, water
and nutrient solution (combined with fertilizer
injector systems) could be placed at the base
of the tomato plant. Initially perlite, in either
bags or buckets, was the rooting medium of
choice with rockwool slabs, and more recently
coconut coir slabs, are now in widest use.
All of the currently used hydroponic
techniques have flaws that have to be dealt
with. The “ideal” hydroponic growing system
has yet to be developed, although initially the
NFT method was thought to be the one that
would come closest.
There are two systems for handling the
nutrient solution, an “open” system in which
sufficient nutrient solution is applied to
the rooting medium necessary to keep it
moist with minimal or little runoff, and for
the “closed” system, the nutrient solution
delivered to the rooting medium is in excess
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and is recovered for reuse.
Ebb-and-Flow (Flood-and-Drain)
Sometimes referred to as flood-and-drain,
a water-tight growing bed, containing either
clean gravel or course sand as the rooting
medium, is periodically flooded for a short
period (5 to 10 minutes) with a nutrient
solution pumped from a supply tank. By
placing the nutrient solution supply tank
below the growing bed, the nutrient solution
can drain back by gravity. This hydroponic
growing system is little used today other
than for hobby-type systems. The method
is inefficient in its use of water and plant
nutrient reagents. Root disease occurrence
and nutrient element insufficiencies can occur
with repeated use of the nutrient solution.
Being a “closed” system, the re-circulated
nutrient solution will require reconstitution,
filtering, and sterilization. Within the
growing period, the nutrient solution may
require replacement. The rooting medium
will require washing to remove root debris
and accumulated precipitates as well as
sterilization before reuse
Nutrient Film Technique (NFT)
A germination cube containing a tomato
seedling is set in a sloping trough of flowing
nutrient solution. The trough can be made of
framed material or consist of a plastic sheet
that is pulled up over the cube, enclosing it
in a pyramid-shaped trough. The slope of
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