Written by Noelina Ashwani Dsouza, staff writer

A recent article in NewScientist entitled- ‘Fertilisers are a major source of microplastic pollution in soil’, shows that the past fifty years have seen a substantial increase in microplastic contamination, which is significantly higher in fields treated with either organic or inorganic fertilizers. This was a long-running experiment by Samuel Cusworth and his colleagues at Lancaster University, UK.

Let’s dive into this plastic predicament, explore what it means for our go-to soil booster, biosolids, and discuss how we might tackle this plastic problem head-on.

Microplastics in Soil: The Sneaky Intruders

Tiny plastic particles measuring less than five millimeters, have been found in soil across the globe. Depending on the kind, size, form, age, length of exposure, and related additives of the polymer, the discharge of plastic residues into the agricultural environment might result in physical, chemical, or biological harm.

Microplastics are a growing problem in agricultural systems that affect productivity either directly or indirectly depending on the additives added to the polymer during production or absorbed from the environment. It’s not just an environmental concern; it’s a potential threat to the health of our crops and, ultimately, our own well-being. Nutrient imbalances, messed-up soil structure – you name it.

Hold onto your gardening gloves because here’s the plot twist: biosolids, the unexpected co-conspirator used as soil conditioning derived from wastewater treatment, are unwittingly carrying these microplastics. These nutrient-rich helpers have been nourishing our soil, but with plastic hitchhikers on board.

The Numbers Game

Let’s put on our data hats. Globally, we’re looking at approximately 12.5 million tonnes of biosolids being generously applied to our fields each year. Agrochemicals coated with polymers, plastic mulch films, crop covers, crop housing, silage films and containers, sacks, and trays are some of the direct agricultural sources of plastic wastes that end up in agricultural soils. Biosolids, wastewater irrigation and equipment, farm machinery wear, organic manure and other field amendments, and air deposition are examples of indirect sources.

Cleaning Up the Act: Can We Bid Adieu to Plastic Intruders?

It is difficult to reverse the legacy of plastic use in agricultural soils. However, researchers are actively exploring diverse methods to address the presence of microplastics in biosolids, aiming to mitigate plastic contamination in soil amendments.

Mechanical filtration, employing screens and centrifugation, seeks to physically separate microplastics based on size and density, while chemical treatments like coagulation and flocculation induce aggregation for easier removal.

Biological methods to eliminate plastics involve microbial degradation and biodegradable additives to break down microplastics over time. Electrostatic separation utilizes electric charges to attract or repel microplastics, and advanced oxidation processes, including ozonation and UV irradiation, target chemical breakdown.

Microplastics can be removed from the environment through activated carbon adsorption which involves using particles with a high affinity for microplastic adsorption, and ultrasonic treatment relies on high-frequency waves for physical breakdown.

These multifaceted approaches highlight the ongoing efforts to find effective and tailored solutions to the complex issue of microplastics in biosolids.

Speeding Up the Goodbye to Plastics

Here’s a thought-provoking idea: what if we hit the brakes on plastics even harder? A quicker ban on certain plastic products could be a game-changer, reducing the impact of plastic footprint.

Conclusion

A direct danger to agricultural productivity and food security is the deposition of microplastics in agricultural soils over time, as most documented interactions between microplastics and soil fauna, plants, microbiome, and crop production are unfavorable. We must re-evaluate our relationship with plastic.

In a nutshell, the revelation of microplastics in our soil is a wake-up call. Our soil is the heartbeat of our food system. From finding ways to evict plastics from biosolids to championing quicker plastic bans, let’s team up to keep our soil healthy and our planet thriving.