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

The 29th edition of UNEP’s Foresight Brief highlights how plastics used extensively in farming – from plastic coated plastic fertilizers to mulch film – are contaminating the soil and potentially threatening food security. Microplastics are also impacting human health when transferred to people through the food chain.

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

Plastics are ubiquitous in agriculture. Macroplastics are used as protective wraps around mulch and fodder. They cover greenhouses and shield crops from the elements. They are used in irrigation tubes, sacks and bottles — and intentionally added microplastics are even used as coatings on fertilizers, pesticides and seeds.

But over time, macroplastics slowly break down into microplastics of shards less than 5mm long – and seep into the soil. These microplastics can change the physical structure of earth and limit its capacity to hold water. That can affect plants by reducing root growth and nutrient uptake. Chemical additives in plastics that leach into the soil can also impact food value chains and lead to health implications.

None of these solutions are a magic bullet. Plastic is inexpensive and easy to work with, which makes trying to introduce alternatives a hard sell.

Elaine Baker, University of Sydney
According to the Foresight Brief, the single-biggest source of microplastic pollution in soil is fertilizers produced from organic matter, such as manure. Known as biosolids, these can be cheaper and better for the environment than manufactured fertilizers. But manure is mixed with microspheres, tiny synthetic particles commonly used in soap, shampoo, makeup and other personal care products, which is cause for concern.

Some countries have banned plastic microspheres, but many other microplastics continue to enter the water system. These include everything from cigarette filters to tire components to synthetic fibres from clothes. Experts say the varying size and composition of microplastics make them difficult to remove once they are in sewage.

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

📚 Facts and figures
• Only 9 per cent of plastic globally is recycled and much of the plastic used cannot be recycled at all. Current recycling systems are not capable of recycling the huge volume of plastic produced, with 46 per cent of all plastic landfilled every year. A life-cycle approach to plastics is needed which looks at everything from extraction of raw resources to product design, production, consumption and waste management.

• While plastic pollution can have a devastating effect on wildlife, it also damages ecosystems, the economy, climate and human health. The production of plastic generated 3.4 per cent of global greenhouse emissions in 2019. Plastic pollution – in the form of microplastics – can also enter the body through inhalation and absorption via the skin and accumulate in organs, including the placenta, and can result in serious health impacts.

• Some of the plastic labelled ‘biodegradable’ requires temperatures of 50°C to be broken down, conditions rarely met in nature. Biodegradable plastic also needs to be separated from non-biodegradable plastic to not compromise the recycling process. Inadequate waste management infrastructure and incorrect waste segregation by consumers make this process complicated.

• Approximately 36 per cent of all plastic produced globally is used for packaging, but every sector contributes to the plastic pollution crisis. For example, more than 45,000 tonnes of plastic enters the ocean every year from industrial fishing gear alone, while approximately 12.5 million tonnes of plastic products are used in the agricultural and farming sector each year.

• Unless there is a change in how plastic is designed, produced, used and disposed of, plastic could emit 19 per cent of all global emissions by 2040. The plastics industry is currently responsible for 6 per cent of global oil consumption. So plastic production needs to be reduced to meet the Paris Agreement target of limiting global temperature rise to 1.5°C.

• Overall, 46 per cent of plastic waste is landfilled, while 22 per cent is mismanaged and becomes litter. Unlike other materials, plastic does not biodegrade. This pollution chokes marine wildlife, damages soil and poisons groundwater, and can cause serious health impacts
• The production of plastic is one of the most energy-intensive manufacturing processes in the world. The material is made from fossil fuels such as crude oil, which are transformed via heat and other additives into a polymer. In 2019, plastics generated 1.8 billion metric tonnes of greenhouse gas emissions – 3.4 per cent of the global total.
• The packaging sector is the largest generator of single-use plastic waste ¬in the world. Approximately 36 per cent of all plastics produced are used in packaging. This includes single-use plastic food and beverage containers, 85 per cent of which end up in landfills or as mismanaged waste.
• Farming is another area where plastic is ubiquitous: it is used in everything from seed coatings to mulch film.
• The fishing industry is another significant source. Recent research suggests more than 100 million pounds of plastic enters the oceans from industrial fishing gear alone.
• The fashion industry is another major plastic user. About 60 per cent of material made into clothing is plastic, including polyester, acrylic and nylon.

📚 Plastic causes land pollution
Remember massive garbage debris in the dumping zone. It contains various hazardous contaminants that seep into the soil, causing land pollution. These harmful toxins decrease the quality of soil by reducing the level of nutrients found in the soil. Nature always gives its feedback. “As you sow, so shall you reap.”