July 14, 2010 | General

Compost-Based Growing System Sprouts Innovation

BioCycle July 2010, Vol. 51, No. 7, p. 40
From commercial strawberry production to urban agriculture, compost encased in mesh material shows some promise in sustainable food production.
Dan Sullivan

WHEN a group of Somali Bantu refugees residing in Syracuse, New York, wanted to establish their own vegetable garden, Filtrexx CEO Rod Tyler collaborated with a local manufacturer located in the historic industrial part of the city not far from the low-income housing projects where the Somali Bantu had relocated.
Tyler had initially discussed the idea of a demonstration community garden project utilizing compost-filled Filtrexx Garden Soxx with Jonnell Robinson, cochair of Syracuse Grows, a volunteer group formed two years ago to support existing community gardens and to help establish new ones. Robinson, a Syracuse University community geographer, says she was initially skeptical. “They wanted to do a demonstration garden right on their plot of land,” she recalls. “At first I hesitated because it was in a heavy industrial part of Syracuse. There are not a lot of neighbors – no community. I thought ‘If you are going to have a demonstration community garden, you need a community.'”
She went back for a site visit in the early spring when the snow was gone and the sun was out and had a different reaction. “It dawned on me how beautiful their property is,” she explains. “Driving back to the university I cut through projects that are a little under half a mile away within easy walking distance – not many of the people in this community have cars – and it clicked. I thought, ‘Oh my gosh, this is good opportunity.'” Robinson contacted Somali Bantu community leaders, who she says expressed great enthusiasm for the idea of having their own community garden. “They have been a target of violence here and there from other members of the African American community,” she adds. “This area is isolated more, and there’s a protective fence around the property.” The presence of daytime factory workers also provided a heightened sense of security. “Time was not necessarily on our side – they wanted to get the garden in, and it was already almost June,” she adds.
With Filtrexx donating the Garden Soxx, the Onondaga County Resource Recovery Agency (OCCRA) donating the compost and local farms and nurseries donating the seedlings, community members and volunteers were able to install the garden on May 30 in about four hours time.
“We are confronted with contaminated soils pretty much throughout the entire city – lead and in some cases arsenic – due to our manufacturing [history],” Robinson explains. “In the past we’ve built raised beds, but that’s expensive – purchasing the lumber and acquiring the machinery to work with the lumber. Garden Soxx are nicer in that regard – you just lay down a barrier over the contaminated soil, and plant directly into these socks.”


Filtrexx CEO Rodney Tyler is no stranger to compost. Based in Grafton, Ohio, his Green Horizons Environmental consulting company was active in the early 1990s during the dawn of compost application for roadside erosion control and in experimenting with various feedstocks for that purpose.
Discussions with civil engineers about the nuances of compost for particular applications led to the development of Filtrexx’s first FilterSock in 2000, a porous compost-containment sock utilized first as a bank stabilization product and, more recently, for agricultural applications. When BioCycle’s sister publication In Business profiled the company in its May/June 2004 issue (“Making Socks That Control Erosion … And Prevent Landslides”), it had already logged more than 4,000 projects ranging from stream bank restoration to helping out Seaworld. Filtrexx now manufactures more than 80 products, including 8-, 12-, 18-, 24-, 32- and 60-inch diameter socks made of cotton, biodegradable plastic, polyester, rayon, polypropylene or high-density polyethylene.
Tyler explains that a breakthrough came with the invention of the FX Machine in 2005, a device that hooks up to a Bobcat. The operator can fill socks at a relatively low investment cost – around $16,000 – versus the $100,000 to $300,000 investment for a pneumatic blower truck.
Currently, Filtrexx is test marketing an already-filled Garden Soxx – 8-inches in diameter by 2-foot-long – at Home Depots in the West and at other garden centers across the country, where they arrive 80 stacked to a pallet and ready to plant. The company also works with regional composters for larger-scale agricultural installations who will go to a farm and fill the socks on site. Tyler says the high-density polyethylene Garden Soxx are the most popular for agricultural applications because they can be used over and over again. They are acceptable for organic production, he says, because the National Organic Program considers them “just another container.”
Filtrexx fills the sock with straight compost, usually made from yard trimmings. “I wrote a book in 1996 that said how not to do this,” Tyler says of the somewhat counterintuitive convention of growing crops in nothing but compost. “It’s a myth that’s never been challenged by anybody except us. We’re utilizing the golden chalice of compost … the same as if you used peat or rice hulls or anything where you know you can get 1-1-1-type media.” That, he says, makes all the difference.
According to Tyler, the compost media remains productive for several years before requiring any inputs such as top dressing with poultry litter. At the Filtrexx research facility in Grafton, he says, “we are in our fourth growing season in the same media.” By year four, Tyler adds, the socks have lost a lot of weight and are shedding key nutrients such as phosphorous and potassium.

Patricia Millner, a research microbiologist with USDA’s Agricultural Research Service in Beltsville, Maryland, began testing the efficacy of various strawberry production systems in anticipation of a phase-out of the soil fumigant methyl bromide that took place in 2005. Her research has zeroed in on both disease suppression and fruit nutrient concentration, and she reports that the Filtrexx system scored high marks for both. The socks not only helped control black root rot, the strawberries grown in straight compost were significantly higher in antioxidants and flavaniods, fructose, glucose, sucrose and other nutritional considerations than fruit produced on either black plastic mulch or matted-row systems.
“We knew that methyl bromide was going to be discontinued, and we were looking for alternative methods especially for strawberries in the eastern United States at this latitude [Beltsville, Maryland],” explains Millner. “We don’t grow them as annuals typically in this region – we grow them as perennials.” The plants start out as bare-root transplants and are typically productive for about three years. Because the developing roots are so susceptible to fungal diseases, methyl bromide has historically been a mainstay of commercial strawberry production. That is until the connection was made between the popular soil fumigant and ozone depletion. “We wanted to show that compost could be a good barrier against the root problem,” she says.
The experiment used runner tip transplants grown in soilless media. Three growing methods were evaluated: direct planting in the soil under black plastic; direct planting into the compost-filled Garden Soxx; and planting into matted rows with no black plastic “which is typically the system you see with strawberries – allowing runners to make a lot of plants and bush out and fill in,” Millner explains. Some of the starts were also dipped in vinegar before transplanting.
“The compost socks did very well,” Millner says, suggesting that heavy feeding strawberries could also easily be fertilized with the drip tape that runs through the Garden Soxx. She also suggests that the Filtrexx system lends itself to both organic production/transition and runner production. “You’d have a completely clean material, and you could clip off the runners and peg them in another sock,” she says, adding that preplanted Garden Soxx could be sold as readymade gardens and hung up on terraces for growing any variety of vegetables or ornamentals.
“The most remarkable thing overall was the effect of compost on different nutritional factors we tested,” Millner adds, noting that a lot of antioxidant benefits were much higher with the strawberries grown in compost rather than in soil. “So growing strawberries in compost is really a good thing – it’s good for the health of the person eating it, and it’s good for the health of the plant.”
She underscores that compost used in the growing system needs to have specific characteristics. “There are certain specifications, such as using mature material with certain particle sizes and density – not super fine or super porous for this particular application … You can tell by the roots how they like it because the whole sock becomes a garden of roots — clean white unlesioned roots. That’s why the foliage is so great – because the roots are so great. I think it’s a great system and there is opportunity for all kinds of considerations. They don’t stay waterlogged, which is what usually creates problems for these root diseases.”

Tyler sees great potential for the Garden Soxx in urban farms and gardens being established on former brownfield sites or abandoned lots with contaminated soils. He offers the real-life example of an abandoned 2-acre industrial lot in Cleveland that soaked up $10,000 for a site assessment and required $50,000 in remediation before it could be utilized in any beneficial way by the community. “That’s $60,000 and you haven’t even started growing anything,” he says. “That would buy 20,000 linear feet of gardens at $3 a foot on the high side.” On top of that, he says, if the city comes up with other plans for the site, as happened with the above example, the installation can be moved to another location.
While the upside of this growing system is compelling, several farmers cited the upfront costs and said it was too early to tell if the payback in increased yields, weed and disease suppression and other touted benefits would be worth the initial investment. “We’ve had some problems with it,” says Steve Moore a veteran organic farmer now doing research at the University of North Carolina Center for Environmental Farming Systems. “I think it holds a lot of promise, particularly in Eastern North Carolina with the idled-out tobacco farms.” That might include, Moore suggests, helping people convert to organic.
“It’s what’s in the socks that counts,” he says. “I think they’re going to a tighter weave, and I think that’s a good thing.” A tighter weave should help mitigate dust issues when the Garden Soxx are being filled, he adds, and should also help with water retention. The coarse material the Center received from a local certified composter “was difficult to wet up – and with the drip tape inside the socks, if anything goes wrong you’ve got to cut the socks open,” Moore says. “It occurred to me that stapling the drip tape on top with 6-inch ground pins would be a better bet.”
Steve Groff, a farmer in Lancaster County, Pennsylvania, did not return calls for this story, but Kip Gardner, Filtrexx’s Director of Agricultural Systems says Groff’s yields were up – but so were his expenses. “He was doing a trial with tomatoes in 1-acre of Haygrove High Tunnel and we persuaded him to try some Soxx,” says Gardner. Groff has been experimenting with different ways of mitigating root disease, including grafting more susceptible varieties onto disease-resistant rootstock particularly suited to greenhouse and high-tunnel production. “He’s had this particular tunnel in the same location for about five years and is starting to have these [disease] issues,” Gardner says.
The Filtrexx system offered an alternative to the native soils. Groff reported a doubling of his yield from 40 tons to 80 tons harvested off of one covered acre. “He’s been very forthright and says ‘I like the system,’ but he’s growing conventional tomatoes for wholesale sales, and this might be more cost than he’s used to,” says Gardner. “He’s going to reserve judgment until he gets into the second year.” While Groff used 12-inch Soxx, the 8-inch sock has proven to be the more common choice for agricultural applications.
Virginia farmer J.D. Scott has grown 20 acres of June bearing pick-your-own strawberries in the same spot for two decades. He was developing some fungal problems, and came to Filtrexx at the advice of his state Extension office. “Extension secured some grant money for a 6,000-foot installation, and one of our local affiliates filled the sock onsite with locally sourced compost,” Filtrexx’s Gardner explained.
“We first planted them last fall,” Scott told BioCycle by cell phone from his strawberry fields in early May. “This is our first year, and we just started picking. People really like the setup; it’s very clean and neat. We like how easy they are to pick, and the berries have done real well. It’s a good deal. We really won’t know until after the picking season, but it’s very expensive to plant an acre like that. I don’t know how [the economics] will work out. They said you can plant more than one year; if that is so and we do that and it works out, then it will cut down on the cost.”
When BioCycle caught back up with Scott at the end of the picking season he reported having had more problems with weeds and cutgrass than he had initially anticipated and that production was about on target with previous years. “I don’t think the compost was up to par with what it was supposed to be,” he says, adding that he plans to clean up the 6,000 feet of Garden Soxx and give them another shot next year. “We’ve been using the matted-row system; normally two years is the lifespan of those, then we do away with them because of diseases. [Filtrexx is] saying four or five years, so we’ll see.”

Sign up