What to do with it when you’re done
For the past half-century, the use of plastic mulch has gained popularity with fruit and vegetable growers. Growing on plastic offers multiple advantages, but when it’s outlived its usefulness, where does it go? Ongoing research is bringing better options for disposal, recycling and biodegradable mulch.
Use of plastic mulch and plasticulture
Producing fruits and vegetables with a plasticulture system allows farmers to maximize early growth and overall yield and minimize weed infestations. In some regions, using plastic in conjunction with raised beds and drip irrigation enhances profitability by expanding growing seasons and marketing windows. Given all these perks, it’s no surprise that the use of plastic has increased by about 5 percent in each of the last 10 years. North American use is believed to be about 600,000 acres annually.
Once limited to black, agricultural plastic mulch is now available in a range of colors from silver to brown. Each color produces different soil temperatures and light modifications, leading Pennsylvania State University researchers to test colors by crop. For instance, red mulch appears to benefit tomatoes in that growing zone by increasing yield and decreasing early blight. Pennsylvania peppers have been shown to thrive on silver mulch. Check with your cooperative extension service for recommendations in your region.
In response to high energy costs in recent years, manufacturers have cut production expenses by reducing mulch thickness. In the last few years, mulch as thin as 0.7 mil or less has been released. While this does drive down costs, the skinny plastic is extremely difficult to remove from the field.
Regardless of thickness, the retrieval and disposal of plastic is a significant challenge for plasticulture growers.
Mulch disposal alternatives
As environmental issues receive more attention, the disposal conundrum is being more closely examined. The nature of plastic and agriculture itself compound the problem. In addition to the difficulties in trashing or recycling plastics, removed mulch is usually covered with soil, plant matter and pesticide residue.
In some operations, mulch can be reused. For example, plastic used for growing spring strawberries can be put to work again for a summer crop. However, bringing out the same plastic year after year is impractical due to possible damage and deterioration, although some success has been reported in dry regions.
Traditionally, plastic has been retrieved manually, but there are alternatives to this time-consuming and labor-intensive process. Mulch lifters, such as Rain-Flo products, deploy coulters to loosen plant residue and soil and blades to lift the plastic. Guides on the blades elevate the mulch to remove soil. The material is then cut in half, allowing soil to drop away when the plastic is lifted. The mulch can then be retrieved by hand or with a commercial collector. Such devices have powered spools to roll up the material.
However the plastic is lifted, the real question is what to do with it. Progress with ideal options such as recycling or repurposing has been slow, but solutions are on the horizon. Some growers bury used mulch on their property, while others burn it. Burning, however, may release potentially hazardous substances and is banned in some areas. Some landfills will accept agricultural plastic.
Recycling and reusing mulch
Low-density polyethylene (LDPE) plastic can be recycled, although the collection and condition issues are obstacles. Black mulch is difficult to recycle, even in those areas where recycling programs exist.
Ag Plastics and Innovations (www.agplasticsandinnovations.com) is piloting a program to tackle the problem of plastic being rejected for recycling due to soil. The Oxnard, Calif., company’s pre-cleaning machine is mounted to a tractor; the three-point machine is lowered over beds and the plastic is fed through the cleaner. A ready-to-recycle bundle emerges.
New Jersey is among the states offering recycling services. Growers can recycle clean, dry irrigation tape and mulch film. A Connecticut program aims to improve the collection and recycling of agricultural plastics. Modified Tiger Balers will collect and bale the material, a strategy expected to cut costs and increase suitability of mulch for recycling.
Although there are several companies and organizations involved in collecting, reusing and/or recycling certain plastics such as pesticide and plant containers, few dealing in plastic mulch have been identified. RKO Industries (www.rkoindustries.com) in LaBelle, Fla., is actively involved in recycling materials such as plastic mulch, irrigation tape and tubing, and fumigation and greenhouse film. The company removes material from farms and transports it to its plant, where it is sorted. No cleaning is needed before the material is processed and resized. It is then washed and dried and converted into resin pellets, which are used to manufacture a range of products. RKO says its services are economical, as compared to the costs of burning or disposing plastic in landfills, estimating a minimal 50 percent savings for an individual grower. Genesis Poly Recycling (www.genesispoly.com) in Mankato, Minn., provides similar services.
At Pennsylvania State University, a process has been developed to convert plastic items, including mulch, into a fuel source called Plastofuel. It can be used in agricultural or community boilers that typically burn coal. A mobile production plant is now being tested. Ultimately, growers may be able to convert their waste plastic into Plastofuel on their own farms.
As recycling efforts slowly develop, researchers are moving ahead with perhaps a better option: biodegradable mulch products. Although these products are costlier up front, the expenses related to removal and disposal are eliminated.
Canadian company Dubois Agrinovation (www.duboisag.com) has several products available for U.S. use; however, the Organic Materials Review Institute here has not approved it at this time. Its compostable and biodegradable black Biotelo mulch film is manufactured from Mater-Bi, a cornstarch material. Temperature, humidity and microorganisms in the soil transform the mulch into water, carbon dioxide and biomass, leaving no toxic residue. A clear version is recommended for sweet corn only. Although Dubois does not release pricing, one vendor offers a 1,000-foot-by-48-inch Biotelo film for $231.
Dubois’ photodegradable product is broken down by sunlight; however, the underground portion doesn’t disintegrate and must be removed. Available in black, brown and clear, the mulch is recommended for sweet corn.
Telles (www.mirelplastics.com) in Lowell, Mass., is expected to soon release its biodegradable product made from a bioplastic called Mirel. This material begins to break down once installed. Following the growing season, growers need only till it into the ground.
Based in Annville, Pa., Robert Marvel Plastic Mulch (www.robertmarvel.com) offers Eco-One Oxo biodegradable mulch. Available in black and clear and assorted widths, it degrades fully in the same manner as the Biotelo product.
All manufacturers recommend purchasing only the quantity immediately needed and carefully storing leftover material in a cool, dark area. Biodegradable products are applied in the same manner as traditional mulch and offers similar production benefits.
Paper mulch has been demonstrated to be as effective as plastic, but tearing has been an obstacle, although newer versions appear to be sturdy enough to avoid that. In addition, large mechanical installation processes may be necessary. Future testing of colored paper mulch is the next step needed in order to bring such products to market.
Based in Greensboro, N.C., the author writes articles about horticulture, landscaping, agriculture and travel. She has been a contributor to Moose River Media publications for three years. Comment or question? Visit www.farmingforumsite.com and join in the discussions.