Long-term localization experiments reveal aging degradation mechanisms of biobased and petroleum-based polyurethanes in natural environments: degradation characteristics, product assessment and degradation cycle prediction.
Tian H, Chen Q, Liu Z, Zhang M, Abolfathi S
Soil Health
Those small plastic-coated fertilizer pellets you spread in your garden or that farmers use on crops are quietly adding microplastics to the soil for generations, and switching to plant-derived coatings could dramatically reduce that invisible, long-lasting pollution.
Fertilizer pellets are often coated in plastic to release nutrients slowly, but those plastic coatings break into tiny pieces that linger in soil for over a century. Scientists tested coatings made from starch and castor oil as greener alternatives, and found they fell apart more than twice as fast as regular plastic and left behind less harmful residue. While even the plant-based versions take decades to fully disappear, they represent a meaningful step toward fertilizers that don't leave a lasting plastic footprint in the ground.
Key Findings
Starch-based polyurethane coating degraded 2.2 times faster than conventional petroleum-based coating over the 807-day experiment.
The starch-based coating is estimated to reach 90% degradation in approximately 75 years in deeply buried soil, compared to 163 years for the petroleum-based version.
Biobased coatings produced fewer toxic byproducts and showed greater fragmentation, higher oxygen content, and more dissolved organic matter after degradation — signs of faster, more complete breakdown.
chevron_right Technical Summary
A nearly three-year field study found that plant-based coatings on slow-release fertilizers break down more than twice as fast as conventional plastic coatings, taking an estimated 75 years to nearly fully degrade versus 163 years for petroleum-based versions — and they leave behind fewer toxic byproducts in the soil.
Abstract Preview
The widespread use of polymer-coated controlled release fertilizers has raised concerns, as it may become a new source of microplastic pollution in the environment. However, there is limited knowle...
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