Overcoming Drought, Part II: Trends in Greenhouse Irrigation By Beth Meneghini

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 wateras cheap and plentiful has slowly begun to change — just ask growers inCalifornia, the Mid-Atlantic, South Florida or the Rocky Mountains, where localand state governments are instituting strict water conservation and reusepractices.

The Water Runneth Out

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

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

Reclaimed water is the product of a wastewater treatmentprocess that eliminates harmful by-products while retaining beneficialelements. Depending on the type of reclamation system used, the treated watercan be “cleaned” to meet safety standards for drinking water orsimply treated for secondary uses such as landscape irrigation or fordecorative fountains and pools.

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

“We were one of the first growers to install a waterreclamation system in our area,” said Doug Mahlstedt, manager of RudvalisOrchids, Carlsbad, Calif. “It just made fiscal and environmentalsense.”

How the Water Works

There are several types of reclamation systems on themarket, but each uses the basic principle of filtering out harmful contaminantsto allow reuse of the water. In a typical system, water runoff is channeledafter irrigation and collected in a holding area such as a pool, pond orsettling tank. Water is then transferred into a separate area to be”cleaned.” Most systems use a series of carbon, charcoal or sandfilters to separate large particles and dirt from the water. Water is thenpassed through stronger filters that kill bacteria, viruses and otherpathogens. These final stages often use UV, infrared, chlorine or ozonefilters.

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

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

At this point, Rudvalis is using the reclaimed water toirrigate landscape plants around the grounds, although Mahlstedt said hewouldn’t hesitate to use the water to irrigate the facility’sorchid crops.

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

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

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

“I was a bit skeptical of using the reclaimed water toirrigate our crops,” added Ryan, “especially on sensitive plantslike poinsettias and small cuttings. But 12 million gallons have been processedthrough the system since installation last December, and we haven’t had asingle problem.”

Runoff Can Break the Law

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

Despite the provisions for enforcement, most statesdidn’t have the time or money to play watchdog to greenhouses andnurseries. But all that seems to have changed. As suburban sprawl moves in ongreenhouse operations and state agencies have begun more frequent monitoring ofcreeks, streams and rivers, greenhouses are in increasing danger of being citedfor contaminated water runoff.

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

In addition to the EPA, the Department of Health and theUSDA, local and regional environmental groups are popping up throughout coastalcommunities in California, Florida and other states to keep greenhouse growersin check.

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

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

Budget Constraints

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

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

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

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

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

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

Another potential pitfall with reclaimed water is increasedsalt content. Salinity will increase with each irrigation cycle and can causeleaf 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 willkeep 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 tomore greenhouse and nursery operations.

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

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

Brazie recommends checking irrigation application and systemuniformity. “Target systems for 85 percent uniformity. Also checkirrigation scheduling and employ the ‘cycle and soak‚technique.'”

For example, if a crop needs 10 minutes of watering time perday, run the irrigation system in three, three-minute cycles instead of one10-minute cycle, advised Brazie. “You’ll get less runoff with a cycleand soak and won’t waste so much water. Even if you don’t installan entire water recycling system, every little bit helps.”

Beth Meneghini

Beth Meneghini is a freelance garden writer based in San Diego and a former editor with GPN. She can be reached via email at [email protected]

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