Plastic is widely used in agriculture for weed suppression, packaging, seed starting, and more. However, studies show that plastic can disrupt soil health, stunt plant growth, and leach from soils into aquatic environments. Here we dive into the issue of plastic in agriculture, and showcase Canadian farmers who’ve found alternatives.
The phrase ‘plastic pollution’ is more likely to bring to mind heartbreaking photos of remote Pacific Ocean beaches littered with plastic or wildlife trapped in six-pack rings than images of earthworms and soil profiles. While marine plastic pollution tends to get the most attention, and for good reason (a recent study of 102 sea turtles in three different oceans found microplastics in the gut of every single one), a 2021 report on agricultural plastics use by the Food and Agriculture Organization of the United Nations (FAO) revealed that there may actually be more plastics in our soils than in our oceans.
Agricultural activities are one of the most direct pathways for plastics to enter soils, with impacts on both soil and aquatic ecosystems, as plastics in soils can travel downstream to rivers, lakes, and oceans. According to the FAO report, plastics used in agriculture represent 3.5% of total global plastic production. While it might seem like a small percentage, 3.5% of total plastic production amounts to a total of 12.5 million tonnes per year. (These estimates do not include food packaging, which is responsible for a further estimated 37 million tonnes of plastic per year.)
Effects of Plastics on Soil Health
While the impacts on soil health have been slow to gain scientific attention, initial research shows that microplastics (pieces less than 5 mm in diameter) can disrupt soil biology, fertility, drainage, and structure, which can affect germination, root growth, and overall plant health. Because of their physical properties, plastic particles also appear to act as a magnet for salt, pathogens, and toxic chemicals in soils. Over time, microplastics can accumulate and travel deeper into the soil profile, through the process of mechanical cultivation, drainage, and soil organisms.
One study in China found that on farms where plastic mulches were used for more than 10 years, the topsoil contained 50-260 kg of plastic per hectare.
Healthy soils are critical to ensuring food security and combating climate change, and preventing plastics from entering soils is one way to protect the capacity of soils to produce food and sequester carbon well into the future.
There’s no denying that plastic has its place – it’s cheap, lightweight, and responsible for many time and cost-saving advancements in agriculture:
- plastic mulches can help with weed suppression,
- plastic drip irrigation allows for more efficient watering,
- greenhouse poly extends the growing season and allows us to grow a wider range of crops in colder climates,
- silage wrap allows farmers to produce and store nutritious feed, and
- plastic bins and crates make for easy harvest, storage, and transport
to name just a few. However, as with many things in agriculture, the use of plastic comes with tradeoffs. It’s unrealistic that plastic will ever be totally eliminated from food systems (and that’s ok), but as ecological farmers it’s worth exploring how we can reduce our dependence on plastic products in situations where there are better alternatives.
How exactly do plastics enter soils?
Plastic can enter the environment through three different pathways, sometimes referred to as the 3Ds: being damaged (a harvest bin is dropped on the ground and a piece chips off), being degraded (plastic tarps left out in the elements slowly disintegrate over time), or being discarded (a drip tape end plug falls out of your pocket in the field). The application of sewage sludge as fertilizer is another way that plastics can enter soils directly. Unfortunately not all of the microplastics present in industrial and domestic wastewater and stormwater are removed during wastewater treatment processes. Of course, plastics can enter soils through non-agricultural activities as well, such as littering or runoff from roads. Plastics that enter the environment through any of these pathways eventually break down into microplastics, which are almost impossible to recover.
Photo: Forrest Farm
What is plastic actually made of?
While there are many different types of plastic, each with its own complex chemical structure, all plastics share two common elements. To make plastic, fossil fuels are converted into hydrocarbon-based resins (PVC, HDPE, etc.), which are then combined with additives (BPA, phthalates, etc.) that give plastic its desired properties, such as flexibility or transparency.
Can’t plastic be recycled?
While some plastic products can be recycled, the reality is that most plastic that enters the waste stream never actually gets recycled into new products. In Canada, where recycling programs and facilities abound, only 25% of plastic waste ever makes it to a sorting facility. Of that 25%, only 9% is actually recycled, either because it is contaminated with residues or because its composition makes it difficult to recycle, which is the case with plastic made from multiple types of resins. Unfortunately, the vast majority of plastic waste in Canada (86%) is sent to the landfill.
The vast majority of plastic waste in Canada (86%) is sent to the landfill.
Agricultural plastic products such as mulches or cell trays have the additional challenge of being very difficult to recycle once they contain soil and plant matter residues. Most recycling facilities cannot process plastics “contaminated” with these agricultural residues. Agricultural plastics recycling could improve in the future, however, with the growth of programs like Cleanfarms. Cleanfarms is a nonprofit organization that partners with retailers to collect and recycle agricultural plastics in Canada, such as fertilizer containers (which can be recycled into drainage tile) and twine (which can be recycled into roofing materials). Currently, Cleanfarms is collecting about 10% of the agricultural plastics used in Canada, but has goals to eventually reach zero plastic waste in agriculture. Find a Cleanfarms collection site near you!
Photo: Bent Plow Farm
What about bioplastics?
Bioplastics is an umbrella term used to refer to plastics that are manufactured from biological ingredients (bio-based) and/or break down into organic matter at the end of their life (biodegradable). Compostable plastics are a smaller category within biodegradable plastics. As the name suggests, compostable plastics can be converted into simple organic compounds, such as water, CO2, and biomass under specific temperature, light, microbial, and oxygen conditions. These conditions are only present in industrial composting facilities, which are rare. Unfortunately, compostable plastics will not decompose in your home compost and are not accepted by most municipal composting facilities. The lack of industrial composting facilities means that currently the opportunities for proper end of life management for compostable plastics are limited. Still, agricultural products made from bioplastics, such as mulches, salad bags, or twine, are growing in popularity. Some advantages of bioplastics include:
- Bio-based products are not made directly from fossil fuels,
- From a leaching perspective, bio-based plastics degrade into microplastics that are less harmful than those of conventional plastics, and
- Biodegradable plastics will break down more quickly than conventional plastics in a waste facility.
Not all bioplastics are created equal
If you do use bioplastic products on the farm, look for bioplastics that are both 100% bio-based and biodegradable, such as PLA. Reuse your bioplastic products until they start to degrade and when the time comes to dispose of them, check with your local composting and recycling facilities to see what they accept. (If they do not accept biodegradable plastics, send biodegradable plastic to the landfill to avoid contaminating recycling or composting streams). If you are using bioplastics for packaging, make sure your customers know how to properly dispose of them as well.
Do your research to ensure specific bioplastic products are actually accepted by your local composting or recycling facilities- many are not.
Are there any better plastic alternatives?
Plastic alternatives are growing in popularity as global tolerance for plastics (especially single-use plastics) decreases. Recently, restrictions on single-use plastics have been gaining momentum, and today approximately two thirds of countries around the world, from Kenya to Lithuania, have enacted regulations or outright bans (usually on plastic bags) in some shape or form.
In Canada, many provinces, municipalities, and businesses have already voluntarily banned certain plastic items, and there is a federal single-use plastics ban in the works. The single-use plastics ban, which could come into effect as early as the end of 2022, would eliminate six of the worst offenders: checkout bags, cutlery, foodservice wares (clamshells, lidded containers, cartons, cups, plates and bowls), ring carriers (6-pack rings), stir sticks, and straws (with the exception of people who need flexible plastic straws for accessibility reasons). These are all products that are either difficult to recycle or often end up as litter in the environment. Today there are reusable or biodegradable alternatives for many common plastic products, from stainless steel straws to fabric shopping bags and packaging made from mushrooms.
Critics often cite the increased financial costs and carbon footprint of manufacturing and transporting plastic alternatives, which can be heavier, more resource-intensive to produce, or involve chemicals that are just as harsh and toxic as those used to make plastic. These criticisms highlight the need to move away from single-use products in general and to consider the environmental impacts at all stages of a product’s life cycle, from design to production, transportation, use, and disposal.
The good news is that there are some alternatives available for farmers looking to reduce their dependence on plastic products, although usually it’s not as simple as replacing a plastic product with a comparable non-plastic one. As the awareness of soil plastic pollution increases, hopefully we will see more substitutes available for plastic farm products in the future. Until then, moving away from plastics on the farm involves the requisite creativity, sacrifice, ingenuity, and trial and error inherent in ecological farming.
Examples of Canadian Farms Working to Reduce Their Plastic Use
Photo: Bent Plow Farm
Alternatives to Plastic Seeding and Propagation Equipment
When Emma and Scott started Bent Plow Farm, a diversified organic market garden on 2 acres of land outside Nelson, BC, there weren’t a lot of durable options for seedling trays, so they started soil blocking from Day 1 and haven’t looked back. Soil block makers, available from places like Lee Valley or Johnny’s Seeds, compress soil into uniform blocks that hold their shape without the need for plastic cell molds. Soil block makers come in different sizes, so you can customize them to your operations and even “pot up” small soil blocks into larger ones. “They produce fantastic seedlings. The roots air prune, they grow really healthy, they experience less transplant shock than transplants from cell trays. We find the plants hold much longer in the greenhouse,” Emma says.
Air pruning means that when the roots reach the edge of the soil block, they dehydrate (as they would in the ground when their roots hit the top of the soil), and the plant gets a signal to stop extending roots in that direction and put its energy into developing roots elsewhere. Making soil blocks is more time consuming than filling a regular plastic cell tray with soil, but Emma says the farm team enjoys this time spent together in the greenhouse, and they save time transplanting because soil blocks don’t need to be popped out (and the seedlings never get stuck in their cells). Some farms build wooden trays for their soil blocks to further reduce plastic use as well.
Madi runs Three Sisters Farm and Greenhouse, a garden centre and nursery in Fernie, BC focussed on supplying the community with sustainable garden products. Prior to starting Three Sisters, Madi was an avid backyard gardener but was often discouraged by the amount of plastic that she came home with each time she visited her local garden centre, whether it was small containers of fertilizer or lots of seedlings in individual plastic pots. It was hard seeing shreds of plastic in the soil plugs when transplanting seedlings, knowing that microplastics are entering soils, air, water, and ultimately our bodies.
When Madi and her husband bought their current 4-acre property, Madi saw an opportunity to create the type of garden centre she always wished she had access to as a home gardener, and Three Sisters Farm and Greenhouse was born. Today, Three Sisters focuses on growing edible, pollinator-friendly, and medicinal seedlings, using as little plastic and as many local inputs as possible.
Photo: Three Sisters Farm & Greenhouse
At Three Sisters Farm and Greenhouse, Madi also grows her plants from seed using soil blocks. Soil blocking is relatively uncommon in the nursery world, but Madi says it has been very well-received by customers, who often comment on how little transplant stress their plants experience! To get around the issue of individually labeling plants (it’s difficult to stick a plastic/wooden label in a soil block), Madi gives customers a sharpie and a cardboard flat so that they can write the types of seedlings on the cardboard flat next to their soil blocks.
For farmers that prefer using pots or cell trays for seedlings, there are some longer-lasting and/or biodegradable options:
- Winstrip Trays have become well-known for their durable design (so much so that they offer a 3-year guarantee against breakage with normal use!). Trays can last upwards of 10 years, and are rigid enough to not need a bottom tray.
- The Paperpot system is another alternative to using plastic seed trays. Paperpots are chains of biodegradable paper cells that are transplanted directly into the soil using a specialized Paperpot Transplanter. A note for certified organic growers: the Paperpot system is not currently certified for use in Canadian organic production due to the presence of adhesives in the paper that are not permitted by the Canadian Organic Standards (although Paperpots have been approved for organic production in the US).
- Pots made from other biodegradable materials, such wood fibre, coconut coir, or manure, can also be used as an alternative to plastic pots. A note for certified organic growers: The use of biodegradable pots in organic production is murky – some products, even though they are “biodegradable”, may contain substances not allowed in the Canadian organics, similar to Paperpots. For example, because Cow Pots are made using recycled newsprint that sometimes contains coloured ink, they are not certified for use in organic production. Check with your certifier before using biodegradable pots, unless they have the Canadian organic logo!
For Madi, moving away from using plastic nursery pots for her trees was also really important. Three Sisters carries bare root stock fruit trees, which means the plants come without soil or a pot. This not only avoids plastic but greatly reduces shipping emissions, as bare root stock trees are lighter and take up less space than potted trees. The trees can be sold directly to customers as bare root stock, or if Madi needs to hold them for longer periods of time, she pots them up into fabric pots.
Fabric pots are much more efficient to transport, and you can fit as many as 300 pots in a single box. Similar to soil blocking, plants in fabric pots naturally air prune their roots. As a result, plants grown in fabric pots develop much bigger, more robust root systems. Madi also offers a buy back program for the fabric pots, where customers can bring in their used fabric pots and Madi will purchase them for a small fee, run them through her washing machine, and reuse them.
Photo: Smart Pots
Alternatives to Plastic Mulches
The issue of plastic mulches in agriculture is complex. Plastic mulches make up the second largest category of farm plastics globally (second only to greenhouse plastic). Many organic farmers especially rely on mulches for weed suppression, and so far there aren’t any perfect plastic-free alternatives.
In 2015, biodegradable plastic mulches were prohibited in the Canadian Organic Standard because all of the biodegradable plastic mulches on the market were found to contain petroleum-derived ingredients (i.e. they were not 100% bio-based). This is still the case, and Canadian Organic Standard has yet to approve a fully bio-based, biodegradable plastic mulch.
Some non-certified organic farmers may still choose to use biodegradable plastic mulch because they see it as the lesser of two evils. Additionally, if you remove it from your fields at the end of the season, the risk of soil contamination is similar to regular plastic mulches (which are allowed in certified organic operations). When it comes to biodegradable plastic mulch, each farm will make decisions based on what makes the most sense for their context.
While it seems counterintuitive, using landscape fabric or even thicker gauge plastic films can also reduce the risk of leaching because thicker mulches are less likely to break down in the field and easier to remove at the end of the season. Additionally, storing your plastics in a protected place when you are not using them will increase their lifespan and prevent weathering that will weaken the plastic and result in microplastics leaching into the environment.
One fully biodegradable mulch option is paper mulch. With this method, a large roll of kraft paper is rolled out over top of the bed and the edges are secured in the same way as plastic mulch (dug in, sandbagged, or stapled). There is no need to pre-burn holes, as holes can be punched at transplanting time, either by hand or with any pointy farm tool, such as a knife, hori hori, or bulb planter. While it is less robust and doesn’t warm the soil in the same way as black plastic mulch, paper mulch still significantly reduces weed pressure and can withstand rain and irrigation. Paper mulch is also relatively inexpensive and is allowed in organic production as long as it doesn’t contain coloured ink.
Other biodegradable options include mulching with a thick layer of compost, cover crops (living or rolled/mowed), straw, or even wood chips, depending on the crop. Many of these options have the added benefit of being produced locally (sometimes even on the farm) and building soil organic matter. (For more information on using cover crops as mulch, check out this resource from the Rodale Institute).
Photo: Ice Cap Organics
In Fernie, Madi has partnered with a local arborist that provides her with wood chips from disease-free trees, which she offers to her customers as mulch. Madi has also found that many farmers are happy to part with their unusable wet hay bales in the spring, which make for a great source of free mulch.
One important consideration is that organic matter mulches tend to create cooler soil temperatures, which can be a disadvantage for heat-loving crops. However, as climate change results in hotter, drier summers, mulches that have a cooling effect may become desirable (and even necessary) for more crops.
Sometimes, the easiest option is to avoid using mulch altogether. Forrest Farm is an 8 acre mixed vegetable and livestock farm in Salmo, BC. The land used to support a diversified farm, but lay dormant for many years before Amanda and Ewan bought it 7 years ago and brought it back into production. Now they run a diversified market garden, and raise pastured sheep, chickens, quail, pigs, and goats. Amanda and Ewan are passionate about avoiding plastic in all aspects of life, both on and off the farm. For them, reduced plastic use is just one of the many dimensions of environmental sustainability that can be achieved on small-scale, diversified, locally-supported farms, alongside reducing their fossil fuel consumption (both directly and indirectly), caring for their livestock and soils, and growing and eating seasonally.
“Being small, and growing enough for your local community is huge,” Amanda says. Reflecting on the rising dependence on plastic on large-scale, industrial farms, “We don’t have to farm like that. We can have hundreds of small farms instead of one big farm where everything is mechanized.” Forrest Farm direct-seeds as much as possible, which eliminates the use of both plastic mulch and cell trays. Amanda admits that without physical weed suppression, “the more energy and time you can put into staying on top of weeding early in the season, the better off you are in the end.”
One Farmer’s Trash is Another Farmer’s Treasure
Kristen runs Naturally Good Vibes Farm, a diversified vegetable farm and apiary on leased land in Langley, BC. For Kristen, trying to reduce plastic waste in farming was also no-brainer. A heavy dependence on plastic felt counterintuitive to what she was trying to achieve through her farming practices, a feeling that many ecological farmers can probably relate to. “It seemed silly to be trying to grow healthy food and help the environment but using all this plastic,” she says.
At Naturally Good Vibes Farm, Kristen sources a lot of her farm infrastructure second hand. For example, she repurposed pieces of an old fence that was being torn down and turned it into pea trellising. Her irrigation system came from another farm that was going to throw it away. When she found out a local refillery was getting rid of some large barrels, Kristen salvaged the barrels and used them to grow potatoes above ground.
Kristen encourages farmers to build connections in their community so you can take advantage of opportunities to give existing plastic products a second life on your farm. “Maybe there’s a farm that’s big enough that they get rid of their irrigation every year,” she says. Don’t be afraid to approach other farmers or ask your local nursery if you can poke around in their garbage, Kristen adds. In most cases, they won’t mind, and if you find something useful it’s a win-win. Of course, it’s important to thoroughly clean and disinfect anything that you are bringing onto your farm to avoid introducing new pests or diseases. This is where having relationships with other farmers really helps, Kristen says, because you know what kind of practices they use and/or what kinds of pests or diseases they may have on their farm.
Photo: Naturally Good Vibes Farm
Kristen is also working on a new project that will help create a more circular economy for used farm materials and infrastructure, and has an exciting invitation for farmers in the Greater Vancouver area: “I’m looking to connect farmers who want pre-owned affordable materials, and farmers who typically dispose of a lot of farm equipment each year. Items such as plastic, drip tape, staples etc. could all be things that farmers swap. One farmer’s garbage becomes another farmer’s treasure. It could be as simple as the farmer picking up what the other farmer doesn’t want instead of them leaving it for garbage pick up, or perhaps the farmer helping take it out of their field as well. If you are interested please email me at: email@example.com”
We encourage you to reach out to Kristen if you are keen to participate in this initiative, either by donating or receiving used farm materials!
Alternatives to Plastic Packaging
Whether it’s sourcing inputs (fertilizer, feed, etc.) or selling products (seedlings, salad, etc.), plastic packaging can be hard to avoid. At Three Sisters, Madi is working on providing her customers with zero-waste soil amendments. Currently, she brings in bulk amendments like Gaia fertilizer (which comes in paper bags), worm castings from Kootenay Worm Composting, and woodchips from the local arborist. Customers can bring their own containers and purchase smaller quantities of these amendments or buy them in reusable pails, which they can return for a deposit. In the future, Madi hopes to purchase a small tractor so she can bring in bulk compost and manure and provide customers with a zero-waste option for these amendments too.
At Forrest Farm, Amanda and Ewan take all of the manure and old bedding from their sheep and goat barns and use it as compost in their market garden, which is one of the ways they avoid bringing plastic from bagged soil amendments onto the farm.
Photo: Forrest Farm
At Forrest Farm, selling direct-to-consumer also gives them a lot more control over how their products are packaged. For Amanda, it’s about removing the option of plastic packaging for the consumer altogether. For example, Forrest Farm’s meat products are wrapped in butcher paper and stamped instead of stickered, and their line of goat’s milk soap and deodorant products all come without plastic containers of any kind. This year, they plan to start making cheese, which will also be packaged in paper, not plastic. When it comes to packaging, Amanda lives by a simple rule, “Stamps not stickers, paper not plastic, bundles not bags.”
Photo: Forrest Farm
At Bent Plow Farm, Scott and Emma are trialing reusable plastic containers for salad with some of their CSA members to cut down on single use salad bags. Each member needs two containers, which is a pricey initial investment for the farm, however so far it’s been well-received. In the future, Emma and Scott hope to expand this system to all of their CSA members.
At Naturally Good Vibes, Kristen also avoids single-use plastics in her CSA. Instead, she uses reusable cloth produce bags and takeout containers which she’s saved or gotten from friends for smaller or more delicate items. For Kristen, this process involved some trial and error. She factored the cost of the cloth bags into the price of the CSA, but admits that it became challenging when customers forget to bring back their reusable bags or containers. It’s hard to know at what point to start charging customers for not returning their items, she says. Using reusable containers is also more time-intensive because you have to wash each item when it’s returned to the farm.
Kristen’s advice for other farmers looking to adopt this model? Make sure you’re comfortable with how much you’re charging, and don’t forget to factor the added labour required to wash containers into the price of your product. And standardize the size of your containers! Having a bunch of different sized containers was “a nightmare”, Kristen laughs. “When I started, food security wasn’t really on a lot of people’s minds,” she reflects, and it was hard to justify charging more for a zero-waste CSA. As consumer awareness of the intersection of food and sustainability grows, however, Kristen is hopeful that it will be easier for farmers to adopt practices that are more in line with their values and still be fairly compensated for it.
Photo: Naturally Good Vibes Farm
Madi is familiar with this struggle as well. For her, providing her community with more sustainable garden products has not always been easy financially. Her profit margins are lower than garden centres who rely on single-use plastics or products that are produced cheaply overseas and imported. However, her work has also provided her with opportunities to build social capital and invest in her community, and her network is constantly growing – a neighbour is going to start sewing fabric pots for Madi next year, another neighbour is going to build wooden trays for her soil blocks, and rather than importing clay pots from overseas, Madi is partnering with a potter in town to provide her customers with a beautiful, local alternative. While it can sometimes be difficult to go against the grain, she says, “Start somewhere, and the opportunities will come up.”
A Delicate Balance
As with most issues of environmental sustainability, the use of plastics in agriculture is not black and white. For Emma, Kristen, Madi, and Amanda, reducing plastic waste is a process, one that involves navigating a complex matrix of tradeoffs and competing priorities. Farmers, Kristen says, are “always trying to balance time, effort, and money”. She knows it can be really hard to step away from tradition, but encourages farmers who may be on the fence about making a change to:
“Just try it… Start with one thing this year.”
It could be switching to soil blocking for certain crops, or introducing reusable salad containers to your CSA, or experimenting with paper mulch on a few beds. Whatever it is, make sure it feels realistic for you and is something that you are genuinely interested in trying.
Photo: Bent Plow Farm
The reality is that when it comes to ecological agriculture, there are no silver bullets, only rusty pitchforks and muddy coveralls. There are still many challenges around reducing plastic use in agriculture, especially for certified organic farmers. As Emma says, “We try to make the best choices that we can with the options that we have.”
Have a strategy or product that you use on your farm to reduce plastic? Share it with us in the comments below!
Want to learn more about plastic in agriculture? Check out these resources:
FAO Report: Assessment of Agricultural Plastics and their Sustainability
UN Working Paper: Plastics in agriculture: sources and impacts
Civil Eats: Ocean Plastic Is Bad, but Soil Plastic Pollution May Be Worse
CBC News: New study tracks agricultural plastics across Canada, with goal of more recycling
NRDC: A Growing Concern: Microplastic Pollution on Farm Fields