No Soil, No Problem
While plastic pop bottles continue to pile up in our landfills, scientists and growers are working together to make this growing problem a growing solution.
September 1, 2009
Plastic pop bottles, for many of us, are another way of referring to polyethylene terephthalate (PET). This thermoplastic polymer is most commonly used to create the containers we use for foods and beverages. It's also one of the most commonly recycled materials in the world.
But did you know that PET is now making a push into the arena of growing media? You read correctly, growing media. So the next time you polish off a bottle of your favorite soda over lunch, make sure to toss it into the correct recycling bin. After all, it may revisit you down the road during your next production run.
Fighter Jets To Begonias
It takes a special person to make the connection between the aerospace industry and the horticulture industry. In this particular case, that special person is Joe Byles, president of Freedom Garden Products.
Byles first began working with PET in the aerospace industry, trying to remedy fuel sloshing in the tanks of aircraft. In doing so, one problem came up. He couldn't get a desired amount of air to escape the material no matter what kind of drainage or pressure was being used. But he did notice in using PET, he could control the pore size of the matter.
As a Master Gardener, Byles thought, "I wonder if I made this the pore size of a sandy loam soil, could I grow plants in an undrained state?" Growing vegetables in two inches of this spongy material, Byles ran successful trials, undrained in the back of his pickup truck. Something he calls the "microclimate from hell," these plants were exposed to hot Texas sun and 70 mph trips up and down the freeway.
From his pickup, Byles began growing plants on solid concrete in the Texas summer. He quickly realized his recycled bottles could impact the growing world.
"No drainage means we can use a very small irrigation source and fill it up at a very slow rate because we are filling up a non-drained panel," he says. "Also, more water held in the volume means less watering." Working with Costa Farms has confirmed all of Byles' hypotheses.
Presently, Byles has teamed with Costa Farms located in Miami, Florida, calling this new technology Aqualok. Ideal applications for Aqualok are hanging baskets, potted plants, green roofs and no-dig landscaping.
"We are currently ramping up things right now and sending out samples to growers," says Costa's Andrew Britten. "We're trying to put this into a much larger production scale this spring." Britten is the grower in charge of the Aqualok trials.
He explains there are two different sides to Aqualok, with the biggest benefits coming in post harvest. For starters, the consumer will not be able to overwater plants grown in the Aqualok foam, because the foam traps the appropriate amount of air, which helps avoid root rot.
With Aqualok, Costa Farms is also seeing the typical dry-down period of straight soil-filled pots extended by up to two times (sometimes more) with the incorporation of Aqualok. Britten says that he's using the Aqualok with his Boston ferns.
"I'd typically water them once a week or once every two weeks," he says. "Now I'm going a month inside my house without having to water. People can go away for the weekend, even the week and not have to worry about their plants drying out. It really adds to the consumer's benefit."
Fits Right In
The grower has a new experience in store, too. "We're basically growing in 50 percent soil and 50 percent foam, which gives us a significant reduction in fertilizer requirements," Britten says.
"We first tried growing exclusively in the foam. But we couldn't get stability to those young plants and we couldn't get fertilizer to them, either." And when it came to controlled-release fertilizer, it would just roll off the top of the foam. "To offset those problems, we decided to go half foam, half soil."
The Aqualok foam was created with a skin on it, which aids in slowing water penetration through the foam. Britten says it mimics soil, and with the addition of a drainage hole, Costa Farms can grow side by side with a straight-soil counterpart using the same irrigation cycles.
"We want this to be as seamless as possible for the people using it," Britten says.
Root development is another interesting facet to the Aqualok technology. "We are seeing that the roots are more fibrous and thicker in the foam than in the soil," Britten says. During one trial, Britten thoroughly saturated an Aqualok pot for a 10-week period. "We didn't see any root rot, which is very impressive, because we'd get rotting in straight soil if we did the same thing," he says.
"We've found in growing with a 50/50 (soil/foam) mix, the roots in the soil actually slowed down and stopped developing, and all the development was in the foam itself."
Mihalek is a former Meister Media Worldwide editor.