A wrap on plastic

Maia Welbel

Plastic pollution is one of the gravest environmental challenges of our time. Hundreds of millions of tons of plastic are produced globally every year, and nearly half of it is discarded after only a single use. Not only is all that material resource-intensive to produce, it’s also toxic to living things on this planet. A growing body of research shows just how pervasive the residues of our worldwide plastic habit have become — and the impacts are cause for alarm.

The use of synthetic polymers in all sorts of technology has come to define our modern lifestyle. Plastic revolutionized medicine, improved sanitation, expanded transportation, and much more. But that convenience and multi-functionality comes at a cost. Plastic litter can take centuries to break down in the environment, and causes ecosystem damage all throughout the process.

Plastic proliferates

Over time, exposure to sunlight, wind, and water causes plastic to break down into tiny particles known as micro-plastics, which spread through land and water systems. Since rising to ubiquity post WWII, plastics made from fossil fuels have seeped their way into ecosystems in every corner of the globe.

From 1950 to 2015, plastic production increased by 448 million tons, and researchers estimate that number will double by 2050. Today, about 8 million tons of plastic waste run into the ocean from coastal nations yearly, killing millions of birds, fish, and other marine organisms. Most scientific research on plastic pollution up to this point has been focused on the impact on bodies of water, but according to a recent report by the FAO, an estimated 80 percent of plastics found in marine environments are first disposed of on land. The earth’s soils are likely just as saturated with plastic, if not more so, than oceans.

‘Plasticulture’ looms large

While domestic and industrial sectors make up the lion’s share of plastic use globally, the FAO report spotlights the particularly potent threat of plastic applications in agriculture.

Plastic is used on farms for crop cover, irrigation tubing, feed storage, and more. For example, film mulch — perforated plastic sheeting laid over fields for plants to grow through — suppresses weeds, improves water efficiency, and increases crop yields. But the proximity of these synthetic materials to soil and food may have frightening consequences for human and environmental health.

Commonly used agricultural plastic products tend to break down readily in the soil, leaving invisible bits behind long after they've done their job. There has yet to be enough land-based research to draw firm conclusions, but studies suggest that plastics can absorb and concentrate pollutants, carry pathogens, and transport toxic elements such as heavy metals into plant cells.

Micro-plastics have been detected in consumables from bottled water to table salt to seafood, but a 2020 study was the first to show micro-plastics had been absorbed into common produce items including apples and carrots. There seems to be general consensus among scientists that further toxicological and epidemiological studies investigating the effects of micro-plastics on human health are necessary.

Though we know plastics aid in convenience and scalability on farms today, the long-term impacts of these materials on soil ecosystem quality and functioning remain unclear. Studies have reported harmful effects of micro-plastics on crucial soil fauna including earthworms, snails, and nematodes. These creatures ingest plastic residue from the soil, which induce toxic effects on their systems. This can throw the soil ecosystem out of balance, and cause cascading effects on both biotic and abiotic soil elements. The migration of soil fauna from upper soil levels with a higher plastic concentration to deeper ones also can impair flow of moisture and nutrients throughout the soil and inhibit water retention ability. Since the accumulation of these materials has happened so rapidly and so recently, we don’t know how severely we might be threatening food security for future generations.

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Taking the long view

As mounting evidence warns of the harms of soil pollution, we need to be funneling resources toward understanding and mitigating the plastic problem. More extensive research should be conducted on the accumulation of micro-plastics on agricultural land, the mechanism by which they travel, how they are or are not absorbed by plants and wildlife, the effects of that absorption, impacts on soil structure, fungi, and other measures of ecosystem vitality. There also must be investment into safer alternatives plastics used in farming.

Alternatives to film mulch, for example, may include compost, grass clippings, and straw. At Zumwalt Acres, a regenerative farm in Illinois, fruit trees are mulched with cardboard covered by wood chips to prevent pest invasion.

The Rodale Institute, a pioneer of organic agriculture, conducted a study on the benefitsof using mulch from cover crops, which can be grown over the winter in the same soil where a cash crop is to be planted in the spring. Cover crops enrich the soil with nutrients and help protect it from erosion as they grow, and once they’re pulled up, their remains act as a great alternative to plastic film mulch.

Small Farm Works, a business in Wisconsin committed to sustainable farming tools, makes a paper chain pot transplanting system, based on a plastic-free technology originally developed in Japan. This tool speeds up transplanting significantly, plus it eliminates the need for the plastic trays and pots that most seedlings in horticulture settings start their lives in.

While recycling will never be a perfect solution, drip irrigation company Netafim is working to reduce plastic waste by collecting plastic irrigation tubing from farms in California and recycling it to produce a resin that is then used for other agricultural purposes.

Taking a holistic approach to farmland conservation, one that is less reliant on plastic and more concerned with long term sustainability, will make our food system safer today and promote longevity for the future.