If
you drive along California’s Central Coast, you will see the ocean on
one side—and oceans of plastic on the other. This is according to Dr.
Seeta Sistla, an assistant professor at California Polytechnic State
University (Cal Poly). “It looks like the sea because it’s so many acres
of plastic that have been put down,” says Sistla, the primary
investigator on two multi-institution research grants studying
biodegradable alternatives to plastic mulch in agriculture. “It’s
absolutely astounding how much plastic use goes into producing
food—plastic that’s then not functionally reusable. And it’s building up
in our soils.”
When we consider plastic in the food system, packaging is usually top
of mind. It’s the largest source of plastic waste globally, with a
widely documented impact, especially in marine environments. But those
clear berry clamshells, produce bags, yogurt containers, and Styrofoam
meat trays lining grocery store shelves represent the very end of
plastic’s journey from field to fork.
Widely used across agriculture and aquaculture sectors—from crops to
forestry, livestock, and fishing, in organic, conventional, hydroponic,
and soil-centered systems alike—plastic touches everything we eat.
That’s because plasticulture—the application of plastics in
agriculture—carries numerous benefits. Applied as mulch and weed
blockers for produce, cover for fruit trees, and wrapping for hay bales,
greenhouse liners, seed trays, slow-release fertilizers, irrigation
systems, fishing nets, milking tubes, packing boxes, pesticide
containers, and so much more, plastic has been increasingly utilized in
agriculture since the 1950s. This versatile material helps boost
efficiency and yields, reduce soil runoff, conserve water, deter pests,
improve sanitation, preserve feeds, and avoid toxic herbicides, among
other functions. It’s also a major source of pollution, one that may be
damaging the very lifeblood of our food system: soil.
And consumers are largely unaware that strawberries, tomatoes, salad
greens, and other produce are frequently grown in rows fitted with
plastic sheeting, that bananas mature in pesticide-impregnated plastic
bags, that polymer-coated seeds sprout from agricultural sites across
the globe, and that modern fishing plainly wouldn’t exist without
plastic.
“Landscapes hide plastic really well. We’ve sampled areas where it
looks like there’s nothing there until you get down and look, and then
there’s all these visible fragments and who knows how much
microplastic,” says Sistla. “Our lab has found that there’s upwards of
10 to over 100,000 pieces of plastic per hectare left behind after clean
removal of this material. And this is not because farmers are not being
careful. . . . But if you use plastic year in, year out, for 20 years,
you see an accumulation, even in really well-managed fields.”
“Landscapes hide plastic really well. We’ve
sampled areas where it looks like there’s nothing there until you get
down and look, and then there’s all these visible fragments and who
knows how much microplastic.”
Despite its deep roots, plasticulture is often overlooked in
mainstream discussions of sustainable agriculture (largely because of
its non-visibility in the public eye), but researchers are increasingly
discovering the practice poses real threats to the future of food
security.
Late last year the United Nations Food and Agriculture Organization (FAO) issued A Call for Action concerning
the long-term impact of plasticulture on terrestrial and aquatic
environments and human health. The FAO found that in 2019 alone, 12.5
million tons of plastic products were used in plant and animal
production, and another 37.3 million tons were used in food packaging.
Most of those plastics are single-use and replaced annually, if not
seasonally. Often possessing little recycling value, millions of tons
end up in landfills or are incinerated, releasing microplastics into
food, fields, air, and water all along the way.
Those plastic particles are known to scale the food web. Now they’re
being found in roots and crops, and even making their way into human blood. Studies confirm that microplastic is altering soil composition too, disturbing the relationship between soil microbes—organisms essential to healthy earth and nutritious foods—along with soil’s ability to absorb water.
That’s particularly alarming, given that scientists estimate
agricultural soils may contain more microplastics than the oceans.
With over 90 percent of global agriculture taking place on land,
finding alternatives to plastics in crop production is critical.
Reducing Dependence and Increasing Alternatives
Dr. Gladis Zinati, director of the Vegetable Systems Trial
at Rodale Institute—a long-term study comparing vegetables grown in
organic and conventional cropping systems side by side with various
management practices—aims to link soil health, plant health, and
nutrient density to human health. The trial, which began in 2016,
implements intensive tillage with black plastic mulch and reduced
tillage without plastic for both its conventional and organically grown
crops.
Black plastic mulch is standard in organic and conventional farming
practices; it’s used to control weeds, expedite production, and reduce
tillage, herbicides, and labor. The FAO confirms that plastic films
(such as mulches, greenhouse films, and silage wraps) represent 60
percent of all plasticulture. Despite their ubiquity, such plastics are
difficult to recycle because of contamination from plant, soil, and
pesticide residues.
One way that farmers can get around this is by growing cover crops and using roller crimpers
(a tractor attachment invented by Rodale that lays said crops onto the
field, creating a dense carpet where sowed seeds flourish and weeds
perish). The cropping method
can supplant the use of over 90 pounds of plastic per acre. It’s also
improving soil health. So far, the Vegetable Systems Trial has shown
that both bacterial and fungal biomass (crucial microorganisms
responsible for decomposing crop residues and building soil organic
matter) are greater in the organic reduced-tillage beds—those that
employ cover cropping and roller crimping instead of plastic. Zinati
notes another important finding: These valuable soil generators weren’t
just fewer in the plasticulture beds; their activity was also ultimately
reduced by the hot environment created by the black plastic.
While the cropping system has obvious benefits, it may not be a fit
for all operations. Straw, wood chips, paper, and even wool all provide
additional substitutes
to plastic mulch. Flame weeders are another long-standing tool, and
Rodale is working on an electric weed zapper to snuff unwanted growth on
vegetable fields. Zinati also recommends rotating crops to help build
healthy soil and planting crops that grow quickly to outcompete weeds.
Biodegradable mulch (BDM) is yet another option, though it’s more
costly and somewhat controversial. Sistla and her colleagues are working
to better understand the viability of BDMs as a replacement for
conventional polyethylene plastic, their use and utility in the field,
and their impact on soil and crops.
“There are no deleterious effects that we can detect of using BDM on
yield, or of the strawberries or quality of the strawberries,” says
Sistla, whose research centers on the popular fruit. “So it seems like
the BDM works well in the field. It’s extremely durable as well. The
thicker BDMs, they’re not breaking down; they’re not falling apart
during the growing season.”
While BDMs appear promising, Sistla is careful to make clear that
“there’s no free lunch, even in the biodegradable world.” Language in
this field can be confusing. “Just because it’s biodegradable doesn’t
mean it's biologically derived,” she clarifies. Such mulches can be
biobased (using natural materials like starch or cellulose), made from
fossil fuels, or a mixture of the two, she notes. To be considered truly
biodegradable by ASTM International,
BDMs must be 90 percent mineralized or transformed into carbon dioxide
under composting conditions within 180 days. If a mulch doesn’t meet
that standard, it won’t break down effectively in fields, and if visible
fragments are left behind, farmers won’t want to use it, Sistla
explains.
Another barrier to adoption? BDMs are unusable on certified organic farms because the technology remains unable to meet the National Organic Program standards,
which require BDMs to be 100 percent biobased, non-GMO, and
compostable, and 90 percent biodegraded in soil within two years of
application.
“There are benefits, but there are lots of disadvantages,” says
Zinati, who remains concerned about the documented adverse effects of
biodegradable plastics on soil. “These could impact the microbes. They
can impact the soil structure, and the physical properties, and the
chemistry.” That could lead to microorganisms spending more energy
decomposing BDMs than providing plants with vital nutrients. As with
conventional plastics, pollutants could leach from particles left
behind, and the accelerated decomposition of BDMs could result in more
littered soils, Zinati cautions. “Researchers have to do more in-depth
work to trace and monitor the degradation of those biodegradable
plastics and how they end up in the soil as well as in the harvestable
crop.”
Sistla agrees that more research is needed to understand the
long-term effects of biodegradable mulch on soil, crops, and human
health—goals that constitute the essence of her studies. “We need to
know more about how quickly these materials decompose in the field and
whether they do have any effects on crop production,” says Sistla,
adding that “if the feedstocks can be refined to be sustainable,
biobased, . . . it could be really, really promising.”
While US farmers have been slower to adopt BDMs, the material is more
commonly used in other parts of the world, notably Europe, where the European Committee for Standardization has developed standards around the use of biodegradable plastic and banned the use of OXO-degradable plastics, given their significant environmental risks, including increased microplastic pollution.
Further research, innovations, and regulations are needed for all
agricultural plastics, including biodegradable and compostable
substitutes, to safeguard essential soil and water systems for a growing
population amid a changing climate, conditions under which
plasticulture is only expected to increase.
Making a Difference: Promoting Visibility in a Complex Food Chain
Thaddeus Barsotti, a second-generation organic farmer and the
co-owner of Capay Organic, a 350-acre certified organic farm in Yolo
County, California, selling fruits, vegetables, and some commodity
crops, says plastic hasn’t increased all that much on his farm since it
was founded in 1976, despite the global trend. Today the largest source
is drip tape, a common irrigation tool that is particularly useful in
arid climates. The farm replaces drip tape seasonally, as crops turn
over, and recycles the material with the manufacturer, which provides
on-farm pickup. “But when you move closer to the customer and away from
the field,” says Barsotti, “you see a lot more plastics.” This is
something he’s actively working to change.
Though the farm sells both retail and directly to consumers via
farmers’ markets and Farm Fresh to You (a CSA delivering approximately
20,000 boxes of food to subscribers per week), 95 percent of Capay
Organic’s produce is found in grocery stores. “Unfortunately, even
though consumers might say that they want plastic-free items, it’s hard
to pull that through the whole food chain,” he explains, citing that
reduction has been a challenge with his supermarket clients.
Barsotti is working to minimize plastic packaging by switching from
plastic bib ties to paper and metal twist ties for bunched greens,
swapping out plastic baskets for cardboard pints for cherry tomatoes,
embracing biodegradable bags, and reducing plastic bag use in general
through Farm Fresh to You. But “[wholesale] buyers don’t look at our
product and give it any more value because it doesn’t have plastic,” he
says. “In fact, I’ve heard the contrary: ‘Love your product. Needs to be
in a two-pound plastic bag, or I can’t sell it.’ And that’s just the
reality.”
“Right now we’re in a system where it is the norm,” says Sistla. “And
there’s good reasons for it from a grower perspective. But if consumers
were willing to pay twice as much for their berries if they weren’t
growing with any plastic at all, that would be interesting to see.”
Though that may sound like a steep price tag, both Barsotti and
Sistla highlight the importance of considering the economic
externalities of plastic. “This is having a real cost to our society,
but it’s not having an economic cost, so it’s getting ignored in our
system,” says Barsotti. “It’s even being encouraged because the economic
benefits of using plastic are so great.”
“This is having a real cost to our society, but it’s not having an economic cost, so it’s getting ignored in our system.”
Farmers and fishers can continue to move the needle on plastic
reduction by making small changes that add up, like swapping plastic
pots for cardboard, plastic harvest bags and Styrofoam fish boxes for
reusable crates, and greenhouse films for glass and polycarbonate.
The FAO finds that action is also needed by business and policymakers
in the form of improved product recyclability and broader access to
recycling infrastructure; development of extended producer
responsibility programs, in which companies are accountable for their
products’ waste; investment in alternative materials, equipment, and
systems approaches; product certifications and standards; and
legislation, both nationally and internationally, including product and
material bans. Global guidelines, incentives, and enforcement would also
go a long way to reduce, reuse, and recycle agri-food plastics.
Widespread consumer awareness of plastic’s true presence in food
production will be fundamental to making waves too. Individuals can take
it further by supporting local farmers and fishers through farmers'
markets and CSAs, discussing their concerns with growers,
self-educating, and advocating for meaningful corporate, social, and
governmental changes. The future of food depends on it.
I agree it is hard to buy fruit and vegetables in containers not made of plastic or covered with cling film (at least it is not all plastic), I like to buy loose and take my own bags with me. Here in Menorca it is much easier to buy local produce but still there is a lot of plastic waste.
The blog song for today is: "Dream a little dream of me" by the Mamas and the Papas.
TTFN
