Across the strawberry fields of Washington, California, Nebraska, and Florida, a massive environmental challenge goes largely unnoticed: nearly a billion pounds of plastic mulch film is buried in American landfills every year. Karl Englund, a research professor of civil and environmental engineering at Washington State University, sees an opportunity where others see waste. New research from his team shows that recycling this contaminated plastic is not just possible—it's practical, offering a path to reduce fossil fuel dependence and keep agricultural plastics from deteriorating into microplastics that poison soil and water.
Plastic mulch film brings real benefits to farmers growing high-value crops like tomatoes, melons, and strawberries. Laid over soil before planting, the film raises soil temperature, reduces water evaporation, and suppresses weeds, leading to bigger yields. Yet of the roughly 500,000 tons of plastic mulch deployed in American agriculture annually, nearly all ends up landfilled or burned. That waste stream represents not only an environmental crisis—as plastics fragment into toxic microplastics—but also a massive drain on fossil fuel resources in an era of skyrocketing oil prices. Most mulch film is polyethylene, and as crude oil prices surge globally, the economic case for recycling grows clearer.
The challenge has always been daunting. Plastic mulch films are thin and fragile, difficult for standard recycling systems to handle. Soil, plant matter, agricultural chemicals, and moisture cling stubbornly to the material, making it nearly impossible to create clean, marketable recycled products. Add to that the scarcity of specialized recycling facilities, and the path forward seemed blocked.
Englund's team—led by graduate student Funmilayo Adesina—tackled the problem by collecting films from strawberry farms across four geographically distinct regions and testing whether they could be cleaned and reprocessed into mechanically sound materials. The results, published in the journal Cleaner Waste Systems, revealed a nuanced reality: recycling works, but success depends heavily on region-specific conditions and rigorous pretreatment.
Soil composition proved decisive. Washington's clay-heavy soils and wet climate created the most stubborn contamination. Even after cleaning, significant soil residue remained embedded in the recycled product, making it stiffer and less flexible. Florida, by contrast, with its sandy soils and hotter, drier climate, produced far cleaner films—contaminants simply didn't adhere as aggressively. Nebraska and California fell somewhere between these extremes. Englund noted the dramatic differences with wry observation: "The fields in Florida are completely different than Washington—I cannot believe they can get stuff to grow in sand. And that stuff just doesn't stick to the plastic."
Despite regional variations, every properly cleaned sample produced usable material. Researchers found that recycled films, when injection-molded into test specimens, were actually stronger than virgin plastic—though stiffer and less flexible. The key to success was pretreatment: ensuring films arrived as clean as possible, then drying and shredding them before processing.
The implications ripple across the agricultural economy. As oil prices surge and landfill space dwindles, recycling agricultural plastic shifts from nice-to-have to essential. Adesina captured the urgency: "Working at the frontlines with my professors in WSU's CMEC in the fight to salvage every single mulch plastic from landfills translates directly into" reducing fossil fuel consumption and environmental damage. With proper cleaning infrastructure in place, the nearly billion pounds discarded annually could become a resource rather than a burden.