Overcoming Drought, Part II: Trends in Greenhouse Irrigation

August 9, 2002 - 09:56

Slowly but surely, growers are recognizing not only the need but also the benefits of reclaiming their irrigation water.

Water is becoming a very precious, and increasingly scarce,
commodity — both in and outside the horticultural community. The view of water
as cheap and plentiful has slowly begun to change — just ask growers in
California, the Mid-Atlantic, South Florida or the Rocky Mountains, where local
and state governments are instituting strict water conservation and reuse

The Water Runneth Out

Less than four-tenths of one percent of the world’s
fresh water is usable for human consumption, according to Tom Kimmell,
executive director of the U.S. Irrigation Association. And as the American
population grows, so does the demand for fresh, potable water. Since the
beginning of this century, per capita water use in the United States has
quadrupled, with Americans typically consuming between 60 and 100 gallons of
water per capita per day.

To help reduce the demand on fresh water supplies, the idea
of using reclaimed water is gaining momentum. Cities like Tucson, Ariz.; San
Diego and Pasadena, Calif.; Austin, Texas; and Tampa and St. Petersburg, Fla.,
are using reclamation systems to conserve water and reduce heavy reliance on
water sources from outside their regions.

Reclaimed water is the product of a wastewater treatment
process that eliminates harmful by-products while retaining beneficial
elements. Depending on the type of reclamation system used, the treated water
can be “cleaned” to meet safety standards for drinking water or
simply treated for secondary uses such as landscape irrigation or for
decorative fountains and pools.

Faced with dwindling water supplies, growers have not only
tapped into their local reclaimed water services, they have started water
reclamation systems of their own.

“We were one of the first growers to install a water
reclamation system in our area,” said Doug Mahlstedt, manager of Rudvalis
Orchids, Carlsbad, Calif. “It just made fiscal and environmental

How the Water Works

There are several types of reclamation systems on the
market, but each uses the basic principle of filtering out harmful contaminants
to allow reuse of the water. In a typical system, water runoff is channeled
after irrigation and collected in a holding area such as a pool, pond or
settling tank. Water is then transferred into a separate area to be
“cleaned.” Most systems use a series of carbon, charcoal or sand
filters to separate large particles and dirt from the water. Water is then
passed through stronger filters that kill bacteria, viruses and other
pathogens. These final stages often use UV, infrared, chlorine or ozone

Rudvalis’ water reclamation system, from Pure O3 Tech,
Escondido, Calif., utilizes ultraviolet radiation, ozone and a configuration of
pumps and filters. The system removes bacteria and pathogens and recovers 50-80
percent of fertilizers for reuse. Mahlstedt reports a savings in the amount of
water the facility uses, as well as a reduction in fertilizer and nitrate

“Our system takes water samples and measures the
amount of nitrates still contained in the recycled water. That way we only
inject the fertilizer we need without adding extras,” said Mahlstedt.

At this point, Rudvalis is using the reclaimed water to
irrigate landscape plants around the grounds, although Mahlstedt said he
wouldn’t hesitate to use the water to irrigate the facility’s
orchid crops.

“Right now, the reclaimed water doesn’t re-enter
our crop irrigation system, but we will eventually pipe it back into the
system. It is on our list of projects for the year,” he said.

Vista, Calif.-based Altman Plants, which grows a variety of
annual and herbaceous perennials and was the 2002 GPN/MasterTag Marketing
Innovation Award winner, also utilizes a Pure O3 Tech water reclamation system.
Once the Altman system processes the water through the filtration system, it is
blended with fresh water before use.

“It’s approximately a 50/50 blend of reclaimed
water and city water,” said John Ryan, a grower for Altman’s.
“We pump the blended water right back into our irrigation system and use
it on all of our crops.”

“I was a bit skeptical of using the reclaimed water to
irrigate our crops,” added Ryan, “especially on sensitive plants
like poinsettias and small cuttings. But 12 million gallons have been processed
through the system since installation last December, and we haven’t had a
single problem.”

Runoff Can Break the Law

Despite inconsistent enforcement, the Federal Clean Water
Act spells out the standards for all discharges off commercial property.
Finalized in 1987, the Act created a federal-state partnership in which the
federal government set the agenda and standards for pollution abatement, while
states were to carry out day-to-day implementation and enforcement. The Act has
two major parts. The first states that all discharges (water and otherwise)
into the nation’s waters are unlawful, unless specifically authorized by
a permit. The second part provides for financial assistance for water quality improvement

Despite the provisions for enforcement, most states
didn’t have the time or money to play watchdog to greenhouses and
nurseries. But all that seems to have changed. As suburban sprawl moves in on
greenhouse operations and state agencies have begun more frequent monitoring of
creeks, streams and rivers, greenhouses are in increasing danger of being cited
for contaminated water runoff.

“The immediate benefit of a reclamation system is the
cost savings on water and fertilizer,” said Ryan. “But the greater
benefit is that the system ensures we are in compliance with state and federal
environmental laws. No one wants to be pumping chemicals into the environment
and endangering our clean waterways. The reclamation system demonstrates
Altman’s philosophy of enterprise in harmony with the environment.”

In addition to the EPA, the Department of Health and the
USDA, local and regional environmental groups are popping up throughout coastal
communities in California, Florida and other states to keep greenhouse growers
in check.

“The California Urban Water Conservation Council
(CUWCC) and the Fallbrook Conservation Service are just two groups that have
started policing the industry for water runoff,” said Jim Brazie,
agricultural sales manager for Hydroscape Products, a California-based
developer of irrigation uniformity and efficiency systems. “But this
certainly isn’t just a Southern California issue. Growers all over the
country will be facing this, if they aren’t already.”

“As housing developments move closer to greenhouse
operations, citizens are also starting to notice and report water runoff from
any business near their homes,” said Mahlstedt.

Budget Constraints

So if a water reclamation system can save growers money on water
and fertilizer bills, as well as prevent costly citations, why don’t all
growers have such systems?

“The easy answer is cost,” said Mahlstedt.
“The initial cash outlay is quite high, and most growers simply
don’t have that much cash lying around for a whole new system.”

According to Can Sirin, Pure O3 Tech, a water reclamation
system can cost between $100,000 and $300,000. But Sirin is quick to point out
that the cost of a system pales in comparison to the potential fine for
violating runoff regulations.

“It seems expensive, but the cost savings in water and
fertilizer is almost immediate, and you completely eliminate the potential of
an EPA fine,” said Sirin.

And while the Clean Water Act imposes water runoff
regulations, it also stipulates funding for growers willing to install systems.

Altman’s received a $50,000 grant from the
Environmental Quality Incentives Program (EQIP), the main conservation program
of the federal Farm Bill, to help cover the costs of its water reclamation

Another potential pitfall with reclaimed water is increased
salt content. Salinity will increase with each irrigation cycle and can cause
leaf burn in susceptible plants.

“Salt content is a concern,” said Mahlstedt.
“But the solution is relatively simple. It takes a bit of forethought,
but if you pass the reclaimed water through a reverse osmosis system, it will
keep your salinity in check.”

Conservation at a Lower Price

Manufacturers and growers alike agree that as time passes,
water reclamation systems will become less expensive, making them affordable to
more greenhouse and nursery operations.

“As purification systems are perfected, more will get
installed,” said Brazie, “and the cost will be reduced. There are
currently only a few companies offering these products and services. But, the
whole system will be streamlined and more affordable in the near future.”

In the meantime, growers can perform a number of tasks to
save money, water and the environment. “Before you even build a water
catch facility or reclamation system, it is absolutely necessary to back up
your current irrigation system and tighten things up,” said Brazie.

Brazie recommends checking irrigation application and system
uniformity. “Target systems for 85 percent uniformity. Also check
irrigation scheduling and employ the ‘cycle and soak‚

For example, if a crop needs 10 minutes of watering time per
day, run the irrigation system in three, three-minute cycles instead of one
10-minute cycle, advised Brazie. “You’ll get less runoff with a cycle
and soak and won’t waste so much water. Even if you don’t install
an entire water recycling system, every little bit helps.”

About The Author

Beth Meneghini is a freelance garden writer based in San Diego and a former editor with GPN. She can be reached via email at beth4473@hotmail.com.

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