This agricultural shortcut promises better harvests. It can hurt the soil. »Yale Climate Connection

When farmer Naiku Gaikwad asked about soil pollution in his village, he pointed out a 40-foot abandoned, filled with plastic.

“After harvesting the crops, farmers here threw hundreds of kilograms of plastic covering into the well,” said a 69-year-old farmer from Jambhali village in Maharashtra, India.

Farmers began using plastic coverings in the village twenty years ago because it provides short-term benefits such as early harvests, improved water utilization efficiency, higher yields and reduced labor costs.

The mulch is a thin, soft sheet, usually black or silver, and farmers spread over the soil like blankets to suppress weeds, retain moisture and regulate soil temperature.

Although farmers remove plastic coverings from the fields after harvest, it is usually impossible to completely remove the coverings because the coverings tend to tear, leaving behind plastic residues. Reuse can cause a large amount of plastic debris to accumulate in the soil. Through exposure to sunlight, changes in weather conditions and farming activities, these residues gradually turn into microplastics, with their particles smaller than five millimeters.

As microplastics break down in the soil, they release climate-warm gases (such as carbon dioxide and methane) by changing soil chemistry and enhancing microbial activity. This process contributes to climate change and damages plants by reducing its ability to perform photosynthesis and absorb carbon dioxide from the atmosphere.

Globally, 4 million tons of plastic coverings are used annually, an increase of 5.6% per year, resulting in the accumulation of microplastic pollution in the soil. A 2016 analysis showed that about 20 million hectares of agricultural land use plastic coverings.

A long-term study in China found that after 32 years, the microplastic level of plastic coverings was 10 times higher than in fields without plastic. The researchers also found that microplastics migrated to deeper soil layers, making it more difficult to remove them.

The study authors warn: “The legacy of plastic pollution will exist in the soil for hundreds of years.”

The researchers found that on average, contaminated soil contains more than 6,000 plastic particles. Agricultural plastics like cover films are an important source of plastic pollution, but plastics can also be accessed into the soil by regularly applying wastewater to treat sludge, which farmers usually use as fertilizer to suit the fields. Plastic particles migrate into wastewater sludge from daily items such as packaging, synthetic fibers in clothing, and personal care products entering the waterway. Wastewater treatment sludge increases only 63,000–430,000 metric tons of microplastics in European agricultural soil each year.

Inorganic fertilizers are chemically produced nutrients used to enhance plant growth and are also a direct source of micro particles. Some have slow or controlled release coatings that gradually release nutrients and contain non-biodegradable polymers that release microplastics into the soil as they degrade.

How microplastics promote climate change

Margherita Ferrante, co-author of the review paper on climate change and environmental microplastics, explained that when polyethylene or polystyrene is shattered by UV light, such as polyethylene or polystyrene is released into the atmosphere by UV light. Ferrante is an expert in hygiene and preventive medicine and general pathology, and is a professor at the University of Catania, Italy. Methane can react with other molecules in the atmosphere to form hot getter carbon dioxide, Ferrante said.

She added that both traditional plastics and biodegradable bioplastics emit a warm climate gas.

Generally, soil stores more carbon in stable form than the atmosphere and vegetation stores. But soil can also emit carbon dioxide, a process called soil respiration that occurs when microorganisms break down organic matter in soil and plant waste.

Without the influence of microplastics, the soil will not emit a lot of carbon dioxide. However, microplastics in soil can trigger higher emissions by altering microbial activity and increasing the activity of certain soil enzymes.

One study found that soil containing low-density polyethylene or lightweight plastics, such as plastic bags, increased eight soil respirations. The plastic coverings used by farmers are made of polypropylene or polyethylene plastic.

Findings from 2023 studies show that when microplastics mix with soil, they change the soil structure, sometimes creating tiny gaps in loose soil. This can improve air circulation, thus giving organisms in the soil more oxygen. This helps them break down organic matter faster, thereby releasing more heat to absorb carbon dioxide.

Microplastics can change soil in a counterproductive way. Study co-author Jin-Yong Lee, professor of hydrogeology and dean of the Office of Research Affairs at Kangwang National University in South Korea, explained that microplastics in the soil cause microplastics that contaminate bacteria, alter soil chemistry, and disrupt nutrient cycles and reduce nutrients in plant nutrients.

And in a study published in March 2025, scientists found that microplastics reduce the photosynthesis capacity of plants and algae by as much as 12%.

Deterioration of crop health

In December 2024, Naiku Gaikwad planted 1,800 watermelon plants, but was unable to kill most of them in eight days due to infestation from pests. He did not make money, but lost money on the crops.

“We use plastic coverings to make sure the pathogens don't reach the roots, and the crops need less water,” he explained.

He believes plastic coverings can protect crops, but instead, it may become counterproductive in ways he never imagined.

When Gaikwad checked his soil, he found it was filled with tiny plastic, which he accused of losing crops.

“My plants cannot effectively fight pests due to the lack of nutrients in the soil,” he said.

Farmers struggle in the absence of regulations

While the plastic coverage soared, not everyone in Jambhali adopted it. Farmer Ashwini Gaikwad (not associated with Naiku Gaikwad), 38, has not used plastic coverings for twenty years of farming.

“I've always doubted whether they work in the long term because I'm worried about their impact on the soil,” she said.

Looking at the results of her neighbor, she felt relieved about her decision.

“I have done everything I can to not bring plastic into the soil.”

But some farmers believe that using plastic coverings is a necessary trade-off. In this case, Ferrante recommends using plant fibers or plates made from natural biomaterials. She warned that they should not be bioplastics, because those containing small polymers that may release micro and nanoplastics over time.

Lee recommends improving waste management systems to prevent microplastics from entering the soil through filtration and recycling practices. More and more research is exploring bioremediation, a natural way to use microorganisms, fungi and plants to manage microplastics in soil. Certain bacteria and fungi form biofilms that help break down microplastics, while plant roots and soil organisms help stabilize or remove them.

Gea Oliveri Conti, associate professor of health and public health at the University of Catania in Italy, said EU regulations aim to prevent and reduce the impact of certain plastic products that are harmful to the environment and human health, and to transition to a circular economy through a sustainable business model.

But Conti recommends that more regulations are needed worldwide.

“The important tool to minimize climate change is to achieve complete management of plastic waste, increase prevention of microplastic dispersions, protect planetary health and address plastic pollution by preventing Virgin plastic production,” she said.

Due to the lack of regulations and installation of climate disasters, microplastics have become a danger. Every month, Naiku Gaikwad watches helplessly as more plastic covering the wells and surroundings.

“The waste you see has been here for 20 years,” he said in frustration, adding, “One day, it's not just in the soil.” “It will be in every corner of the world. By then, it's too late.”