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"When I started thinking about this five
years ago, there wasn't a water shortage in Central Florida," said
Holloway, "I just wanted to grow better plants."
The Holloway irrigation system, which
recycles collected rainwater and doesn't discharge any wastewater into
the environment, is drawing wide-ranging interest from
environmentalists who want to stop the drain on Florida's theatened
water resources.
Nurseries are a fast-growing -- but
water-intensive -- industry in Central Florida. Ornamentals and
grasses accounted for almost a third of agricultural irrigation use in
the district, drawing about 110 million gallons a day of potential
drinking water from the underground supply.
Holloway estimated that his system
annually saves 4 million gallons of water per acre.
The St. Johns River Water Management
District has given Holloway a grant of $70,000 to help develop the new
irrigation system, and both the Department of Environmental Protection
and state agricultural officials are eager to see whether it can work
in the field.
"There's a grower in South Florida who
wants one, and there's been interest in the Middle East in it," said
Holloway, who only recently started to publicize and market the
irrigation system.
Other growers have experimented with
ways of re-using water, but Holloway said his system is one of a kind
because it combines a long-established practice -- root irrigation for
better plant growth -- with a closed irrigation system to recycle
water.
"This is unique -- I don't know of
anything like it," said Joe Hill, a member of the Lake County Water
Authority and former member of the St. Johns River Water Management
District.
Nursery operations have toyed with a
similar concept called "ebb and flow" for years, but no one thought it
could be used on a large scale, said Mike Thomas, an engineer with the
Florida Department of Environmental Protection, who has evaluated the
system.
"They all thought it was impossible,"
he said.
But Holloway has showed that a fairly
large system can work, and Thomas said DEP is pushing for federal
funds to build an even larger demonstration project.
Back to the future
The system hinges on the concept of
watering from the roots up -- an idea as ancient as agriculture
itself, Holloway said.
"It is more efficient to irrigate from
the roots up -- there's evidence they were doing this in ancient times
along the Tigris and Euphrates," said Holloway.
It has only been in the last hundred
years or so that growers have resorted to overhead irrigation, which
is much more wasteful of water and relies on motors and irrigation
lines. But overhead irrigation methods and even state-of-the-art
microjet irrigation sprinklers on the soil surface can not distribute
the water evenly around the plant roots.
"There are dry spots in the pot, which
means only a portion of the roots are actually working," said Michael
Holloway, a son and vice president of the nursery operations.
Holloway simply puts his potted plants
on a polyethylene liner that covers about half an acre. Every few
days, the liner is flooded for about half an hour, allowing the plants
to soak up moisture evenly from the roots up.
The water then is drained back into a
lined holding pond about 8 feet deep until needed again. Because the
water isn't sprayed on the plants and there is little evaporation and
because the entire area also acts as a rainwater collector, there is
no need to pump ground or surface water to replenish the holding pond.
"There are two basic principles here
-- flood irrigation and a closed-loop system," said Michael Holloway.
"We don't need to pump water out, and we don't discharge any water
into the environment."
20 inches of rain will do
As long as 20 inches of rain falls a
year, the system is self-sustaining, he said.
And as dry as it has been in the past
three years, rainfall totals in Lake County have never dropped below
30 inches a year.
Saving water wasn't the objective when
he started working on using kiddie swimming pools for growing plants
five years ago.
"I just wanted to grow better plants,"
said Rufus Halloway, who grows live oak, crape myrtle, ligustrum,
cypress and magnolia.
He initially put the potted plants in
the plastic pools to see how they would fare when watered from the
bottom rather than the top. Not only did they grow bigger and faster,
they used less water.
"I'd tell my nursery manager we ought
to water them again, and he'd always say they've got plenty of water,"
said Holloway.
He quickly realized that watering from
the roots up made the plants grow faster because the entire root
system was getting moisture, which allows the plant to grow more
efficiently. And because the water was coming from below, there was
less evaporation, and the plants' roots stayed moist longer while
using less water.
Then Holloway got inspired to create a
closed irrigation system, which would simply reuse water to cut costs
and labor.
He built a 3-acre demonstration system
on his 50-acre nursery three years ago and last year added a second
one.
Unexpected advantages
"Ninety-nine percent of the water
that's not used by the plants is reused," said Holloway, who said he
has found a number of unexpected benefits.
Aside from higher crop yields and
growth rates, the system drastically reduced pumping and electrical
costs and eliminated many common plant diseases that are caused when
the plant itself is watered.
Holloway also said ultraviolet light
rays reflect off the polyethylene liner and act as a natural
pesticide, greatly reducing the need to spray for bugs.
"The last five years have been
research and development -- it's been an experiment," said Holloway.
"But now we know it works, and we're ready to spread the word."
Ramsey Campbell can be reached at
rcampbell@orlandosentinel.com or 352-742-5923.
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