Recycling Agricultural Plastic I

Summer 2019
David McDaniel's third high tunnel
The author’s third high tunnel with a fourth shown under construction. Photo by David McDaniel

By David McDaniel

Maine commercial farmers are addicted to plastic. Whether we farm organically or conventionally, the economics of modern farming drive our dependence on petroleum-based plastic products.

We use acres of black plastic mulch to warm our cold northern soil and eliminate mechanical weeding or chemical herbicides. We lay miles of plastic drip tape under this impervious mulch to irrigate our fields. We drape white spun polypropylene row cover from 1,000-foot rolls for frost and insect protection.  Plastic high tunnels are popping up like spring onions, fueled by generous USDA NRCS grants and a frenzy of legalized cannabis growers. Silage bales and bunker plastic have replaced the barns and silos of an earlier era. Vegetable farmers increasingly use these same black silage tarps for occultation – a no-till method of suppressing weeds.

Farmers love plastic because it is extremely cheap, our profit margins are small and we search for every financial competitive advantage. Compare the expense of silage bales to concrete silos, or of a glass greenhouse to a poly-covered high tunnel – no contest. Plastic saves time and dramatically decreases labor costs. A single mechanized application of black plastic mulch and drip tape replaces repetitive mechanical field weeding and lugging heavy overhead irrigation pipes.

Consumer choice drives our addiction. Poly-culture has significantly expanded our growing season and increased the menu of locally available produce. We all compete to be first to market in the spring and last to harvest in the fall. Ginger and turmeric anyone? Coming to a farmers’ market near you!

But is our plastic addiction adding to environmental degradation? Where does all that plastic go at the end of its useful life?

The dirty secret of agricultural plastic is that it is considered too dirty to be recycled easily. Recycling plastic in Maine is based on sorting post-consumer waste using the familiar resin identification codes 1 through 7 and then selling this relatively clean material to various end users. Agricultural plastic never fit neatly into this recycling model, since it comes in a confusing array of non-consumer products, often not labeled with a resin code and almost always heavily contaminated with soil, water or agricultural residue.

In the best of times, Maine commercial recyclers never wanted to recycle agricultural plastic. Now these are the worst of times. The national plastic recycling market is in a state of extreme disruption as China, formerly the biggest end buyer of U.S. plastic waste, has stopped accepting new plastic shipments. As Vic Horton, executive director of the Maine Resource Recovery Association, eloquently said, “China woke up and decided they didn’t want any more of our garbage!”

Nobody knows exactly where all this agricultural waste plastic is going. Most probably ends up in landfills. Some may be repurposed and burned in a waste-to-energy facility. A very small amount is heroically recycled. A few years ago I witnessed my Thorndike neighbor Wini Noyes washing used black plastic field mulch and hanging it up to dry so that it was clean enough to be recycled!

How much unrecycled agricultural plastic are we talking about? No definitive federal or state data are available, but a few estimates paint a depressing picture.

Jean Jones, executive director of the Southern Waste Information eXchange in Florida, estimates that total U.S. agricultural plastic waste is between 800 million and 1 billion pounds per year. Using farm census data we can estimate roughly that Maine’s farms produce approximately 488 pounds of plastic waste per farm per year, for a total of 4,003,906 pounds annually. This conversion from national data doesn’t appropriately weigh heavy-use states such as Florida and California, so we need to dig a little deeper.

Price Murphy, director of operations for Revolution Plastics (a Midwest company specializing in recycling plastic dairy waste), estimates that Maine’s 227 dairy farms produce approximately 1 million pounds of plastic waste per year. A University of Maine Cooperative Extension workgroup looking at recycling greenhouse plastic estimates that Maine discards 20 to 30 tons of greenhouse and high tunnel plastic each year. Data from the Virginia-based Ag Container Recycling Council indicates that Maine farmers discard 108,158 pounds of pesticide containers (organic and nonorganic) each year, excluding 55-gallon drums.

Missing from these numbers are the additional large volumes of plastic mulch, row covers and drip tape, plus plastics from the nursery industry. Jones says nursery containers alone make up almost half of the national totals.

Our rough estimate of 4,003,906 pounds of annual Maine agricultural plastic waste may be depressingly accurate.

The final problem with this ubiquitous polymer is its environmental persistence and possible biological toxicity. Plastics not only degrade excruciatingly slowly, but some types do so by breaking down into smaller, persistent nanoparticles that are becoming alarmingly common in the world’s drinking supply and appear to be accumulating and cycling through our food chain from the North Pole to Antarctica. Depending on the individual chemical constituents, the plastic may pose serious health hazards such as hormonal and endocrine disruption in susceptible organisms. A million years from now, a future non-human archeologist may see this layer of human-produced plastic particles in the geological record and label our extinction the Plasticene era!

Long-term solutions to our addiction to agricultural plastic are complex. In the short term I recommend eliminating as much plastic from farming operations as is economically feasible, and often even when it is economically disadvantageous. Prioritize your use of plastic. Eliminate disposable single-season products. Is mechanical weeding and straw mulch a better option than plastic mulch? Use plastic that has a multi-year lifespan. Find substitutes.

Part II – Recycling Solutions will appear in the fall MOF&G and will discuss best practices for using and recycling specific types of agricultural plastic.

About the author: David McDaniel co-owns and farms Earth Dharma Farm in Jackson, Maine. He chairs the Ag Plastic Recycling Committee for the University of Maine Waldo County Extension Association and is a board member of the Unity Area Regional Recycling Center. You can reach him at [email protected].

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