 Should
a Grower even consider Flood Floors in a single Quonset house?
Or in a couple bays of gutter-connected houses? Maybe!
So far mostly larger operations have installed Flood
Floors. The reason was not necessarily high initial costs,
but the lack of experience with such systems. With little
support available, it took a good measure of pioneering
spirit and resources to do the jump. This has changed
now. Small and medium size growers discover that they
can have the same benefits larger ones do: saving labor,
uniform watering, dry foliage for reduced disease problems,
flexible use of the growing space, low maintenance, full
water recirculation.
The Technical Side
There is no limit to how small and
simple Flood Floors can be. A tree nursery in Oregon
fills a plastic lined
100 square foot section of greenhouse floor with a garden
house. Different size Flood Floor systems call for different
designs. Simply scaling down a large system will make
it expensive and often impractical.
Some features
are common to Flood Floors of any size:
• The plants sit on concrete floors, which are pitched just enough to ensure
puddle-free drainage.
•Curbs or special rubber barriers separate
the floor area into manageable watering zones,
which generally correspond with the bays of the
greenhouse.
• Each watering zone is filled 1 - 2 inches deep with water, and drainedagain.
The plants sit in the water for less than 10 minutes. This is time enough for
the capillary
action to provide a thorough watering, but not
long enough to allow pathogens to migrate into
the surrounding water.
• Floor heat is crucial for the optimum microclimate and provides valuable
control of the root temperatures. Larger floor heat systems typically tie in
with the overhead heat. Small systems can be as simple as a small boiler and
a circulation pump connected to the in-floor tubing.
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Other features vary with the size and application of
a system. A system of 10,000 square feet or more typically
has:
• 10 — 100 watering zones of 1000 — 6000
square feet each
• Short watering times of an hour
or less per acre
• Two or three solution storage
tanks that allow the grower to choose between fertilizer
mixes or plain
water
• Low maintenance water filtration
• Fully
automated operation, often integrated with an environmental
computer. As the systems get smaller,
the picture changes.
• The number and size of watering
zones decreases. More and smaller zones add flexibility,
but cost marginally
more to install than fewer large ones.
•
There is less need to push for high speed. Even a 'slower'
system will water every thing in less than an hour. However,
we still want to be sure the water
does not sit for more than 10 minutes on
any watering zone.
• Experience shows that a choice of one or two
fertilizer solutions covers the needs of most small growers.
With
appropriate design it is easy to add more tanks later
if needed. The higher costs for in-ground tanks are usually
justified in larger systems; the smaller ones typically
have above ground tanks for ease of installation. The
size of the tanks is largely determined by the size of
the watering zones, and not much by the number of zones
in a system.
• Even the smallest systems normally
run unattended on a programmable irrigation controller.
It's the Economy
 No matter what the size of a Flood Floor system, the
initial investment is considerable. Realistically we
look at $ 4.50 - 6.00 per square foot. Now don't stop
reading yet! These numbers include all materials and
all (often hidden) labor costs from design to operating
system. And it buys more than a labor saving irrigation
system: concrete floors for flexibility and sanitation,
floor heat for better growth and disease control, and
a leap ahead of any environmental regulation.
Flood Floors are a long-term investment, with 10-20
years of low maintenance operation to be expected. For
many smaller growers such up-front investment is out
of reach, even if it pays back handsomely. That's where
another aspect of Flood Floors comes in: practically
all technology involved is simple. A grower with some
handyman-skills can do almost all the work himself and
with his crew. And not all work needs to be done at once.
It is common to put the piping into the ground, pour
the floors in increments, and add tanks, pumps and controls
as the situation allows. Well draining concrete floors
are an asset even before the flooding is operational.
Where Flood Floors of any size may not be a good investment:
Inexpensive greenhouse space that is used only seasonally
for bedding plants is not a likely candidate. While many
bedding crops do well on sub-irrigation, it is really
the potted crops where the payoff comes in. Flood Floors
can easily be installed in existing greenhouses, but
if they are likely to outlast the structure, they can
turn into a liability.
Ebb and Flood Bench systems are helpful where manual
work on the crops is required. However, cost, high maintenance
and labor-intensive handling on fixed and rolling benches
make the floor option attractive for many growers.
Going for the Floors
Flood Floors are essentially simple. But well functioning
simplicity is the result of competent design and lots
of experience. Connect with growers who have built and
operate Flood Floors. Talk to professionals about the
many options to tailor a system to your specific needs,
and prevent unnecessary expenses.60 - 70% of the cost
of Flood Floors lie in the concrete work. Sophisticated
concrete placing and finishing equipment can be helpful,
but is not essential for good floors; experienced and
careful people are. Laser leveling is indispensable.
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