The massive use of plastic in agriculture affects our health, that of the soil and food production

Plastics are accumulating in the world’s soils at a worrying rate, according to a new report from the United Nations Environment Program (UNEP).

The 29th edition of the agency’s Foresight Brief highlights how plastics widely used in agriculture, from plastic-coated fertilizers to mulch films, are polluting the soil and potentially threatening food production and our access to to them.

They are also affecting human health when transferred to people through the food chain.

“There is only a finite amount of agricultural land available,” Professor Elaine Baker of the University of Sydney, co-author of the report, reminds us. “We are beginning to understand that the accumulation of plastic can have wide-ranging repercussions on soil health, biodiversity and productivity, all of which are vital for food security,” she says.

Macro and microplastics

Plastics are omnipresent in agriculture, both through macroplastics and microplastics, which are the ones that end up in our food chain.

Macroplastics are used as protective wrappers for mulch and forage. They cover greenhouses and protect crops from the elements. They are also used in irrigation tubes, bags and bottles.

Over time, macroplastics slowly break down into fragments less than five millimeters in length, and seep into the ground. In addition, there are also intentionally added microplastics, which are even used as coatings for fertilizers, pesticides and seeds.

These microplastics can change the physical structure of the soil and limit its ability to retain water. This can affect plants by reducing root growth and nutrient uptake.

Chemical additives from plastics that seep into the ground can also affect food value chains and have health consequences.

According to the report, the largest source of microplastic contamination in the soil is fertilizers produced from organic matter, such as manure. Known as biosolids, they may be cheaper and better for the environment than manufactured fertilizers, but the manure is laced with microbeads, tiny synthetic particles commonly used in soaps, shampoos, makeup and other personal care products, which is cause for concern. concern.

Plastics are ubiquitous in agriculture, affecting our health, the health of the soil, and food production. (Photo: FAO / Cristina Aldehuela)

Substitution for nature-based solutions

Some countries have banned plastic microbeads, but many other microplastics continue to enter the water system. These include everything from cigarette filters to tire components and synthetic fibers in clothing.

Experts say the variable size and composition of microplastics make it difficult to remove once they’re in wastewater.

Progress is being made in improving the biodegradability of polymers used in agricultural products. Some mulch films, used to modify soil temperatures, limit weed growth and prevent moisture loss, are now marketed as fully biodegradable and compostable, which is not always the case.

To reduce dependence on hydrocarbon-based polymers, the use of biobased polymers is becoming more widespread. But not all are biodegradable, some can be as toxic as fossil fuel-based polymers, and their price remains an issue.

Experts say that the production of bio-based polymers must include considerations of sustainable agriculture and can be replaced by nature-based solutions. For example, so-called cover crops can be used, which protect the soil and are not intended to be harvested. This strategy can suppress weeds, counteract soil diseases and improve soil fertility, but there are concerns that it may reduce yields and increase costs.

Follow the path of the European Union

“None of the (nature-based) solutions is a magic bullet,” says Baker. “Plastic is cheap and easy to work with, which makes trying to introduce alternatives a hard sell.”

According to her, governments must “disincentivize” the use of agricultural plastics, following the path of the European Union, which earlier this year restricted the use of certain types of polymers in fertilizers.

Baker said that more research is needed to develop products, such as some of textile origin, that do not release microplastics. Encouraging consumers to rethink their plastic consumption and encouraging manufacturers to reduce the amount of plastic they use is also essential, she said.

“Although research on the impact of plastics on soil is still limited, there is evidence of negative effects on soil health and productivity,” says the expert. “Now is the time to embrace the precautionary principle and develop targeted solutions to stop the flow of plastic from source to the environment.” (Font: UN News)