Microbial networks and soil properties influence surface biodegradation of polyethylene terephthalate (PET) and polylactic acid (PLA) in soil.
Holt ZK, Herrera GJ, Faria LUS, Lupini S, Nascimento CAO
Soil Health
The plastic mulch film, plant pots, or packaging scraps that end up in your garden soil break down at very different rates depending on whether your soil is alkaline or acidic — meaning your garden's chemistry is quietly either fighting or fueling plastic pollution right now.
Scientists buried two types of plastic — a common bottle plastic and a 'compostable' packaging plastic — in 16 different soils and left them for 300 days. They found that both plastics did start to break apart on the surface, but soils that were more alkaline and rich in certain minerals allowed the resident bacteria to do a much better job of breaking the plastic down. This means that the natural chemistry of the ground beneath your feet plays a huge role in whether plastic pollution lingers for decades or gets quietly dismantled by microbes.
Key Findings
PET plastic showed up to 38% reduction in surface carbonyl index after 300 days, while PLA showed up to 36%, confirming measurable biodegradation in real soil conditions
Plastic surface hydrophobicity dropped by 52% for PET and 26% for PLA, with alkaline, carbonate-rich, higher-conductivity soils driving the greatest transformation
Plastic exposure significantly restructured soil microbial communities, enriching known plastic-degrading bacteria (Bacillus, Burkholderia, Pseudomonas) around PET and broader metabolic specialists around PLA
chevron_right Technical Summary
Researchers found that common plastics — including PET (used in bottles) and PLA (a compostable plastic) — do measurably break down when buried in soil, but how fast depends heavily on the soil's chemistry and which microbes live there. Alkaline, mineral-rich soils hosted microbial communities that degraded plastic surfaces the most, offering a path toward using soil biology to clean up plastic pollution.
Abstract Preview
Plastic accumulation in terrestrial environments poses increasing ecological and public health risks, yet the mechanisms driving plastic biodegradation in soils remain poorly understood. Here, we i...
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