Plastics in soil threaten health and agriculture

A lot of the talk surrounding plastic pollution focuses on its impact on marine ecosystems. But there may actually be more microplastic pollution in the soil than in the ocean, according to UN research.

The UN’s Food and Agriculture Organization (FAO) has released a report warning of the “disastrous” impacts of the use of plastics in agriculture.

“The report serves as a loud call for decisive action to curb the disastrous use of plastics across the agricultural sectors,” FAO deputy director general Maria Helena Semedo wrote in the report foreword.

Plastics are used in agriculture for a variety of purposes, from mulching films to plastic tree guards to controlled-release fertilizers coated with polymers. In fact, world agriculture used 12.5 million tonnes (approximately 13.8 million U.S. tons) of plastic for plant and animal production in 2019 and 37.3 million tonnes (approximately 41.1 million tonnes) for food packaging the same year.

While plastic can be beneficial to agriculture, its widespread use also raises concerns about its impact on public health and the environment when it degrades.

This is especially concerning for the world’s soils. When microplastics from mulching film build up in surface soils, for example, they reduce agricultural yields. There is also a concern that microplastics in agricultural soils could work their way up the food chain to harm human health. Some plastics contain toxic chemicals themselves, and plastics can also collect and transport diseases and chemicals when they enter the ocean.

University of Sheffield professor Jonathan Leake told The Guardian that there was evidence that plastic pollution in the soil harms earthworms, which are important for soil health.

“Plastic pollution of agricultural soils is a pervasive, persistent problem that threatens soil health throughout much of the world,” he said. “We are currently adding large amounts of these unnatural materials into agricultural soils without understanding their long-term effects.”

The UN agreed that more research is needed to understand how plastic pollution is impacting the world’s soils.

“The trouble is we don’t know how much long-term damage the breaking down of these products is doing to agricultural soils,” Mahesh Pradhan, coordinator of the UN Environment Programme’s (UNEP) Global Partnership for Nutrient Management, said in a recent statement. “We need to develop standardized methods of detecting microplastics in soil to better understand how long they remain there and how they change over time.”

The FAO report also called for improving the management of agricultural plastics through “the 6R model” – refuse, redesign, reduce, reuse, recycle and recover. More specifically, potential solutions could include changing practices to phase out plastic altogether, replacing plastics with biodegradable alternatives or designing better ways to manage or reuse plastic waste.

Innovation is also a possible solution, Kristina Thygesen, a senior expert at GRID Arendal who is collaborating with UNEP on agricultural plastics, said.

“Right now, a farmer might use plastic to control weeds, but maybe a small machine could be developed that can recognize weeds and remove them,” she said in the UNEP statement. “We live in a high-tech world, and we can find solutions if we really want to. We need to develop a new generation of agricultural technology.”