Farmland contaminated with PFAS, the so-called “forever chemicals,” has traditionally been cleaned up by excavating and incinerating soil — a process that costs $800,000 to $1.6 million per hectare and takes the land out of production. A Yale-led research team says it has found a far cheaper alternative that lets contaminated cropland stay in use while it’s being remediated.

The method, described in the Proceedings of the National Academy of Sciences and based on data from agricultural sites in Maine, combines two ideas that don’t usually appear together: PFAS cleanup and carbon removal. A thin layer of crushed alkaline rock spread over a field raises the soil’s pH, which speeds up how quickly plants absorb PFOS from the ground. The harvested plants are then converted into biochar through heating, a process that destroys both PFOS and PFOA. The same alkaline-rock approach is also used in “enhanced weathering,” a strategy for pulling carbon dioxide out of the atmosphere, and the team estimates the system could remove 10.5 million metric tons of CO2 a year nationally while treating the soil.

The researchers put the new method’s cost at about $1,460 per hectare per year; repeated over 20 years, including compensation for farmers’ lost income, the total comes to just over $29,000 per hectare — versus roughly $8 trillion if conventional remediation were applied nationwide. First author Jake Thompson, a Yale postdoctoral researcher, estimates that 1.2 million hectares of U.S. cropland, nearly 3 million acres, may be significantly affected by PFAS contamination, much of it traced back to sewage sludge that was marketed to farmers as fertilizer before the risks were understood. Maine discovered PFAS in milk from a contaminated dairy farm in 2016 and banned sludge application on farmland in 2022; PFOA was classified as a human carcinogen in 2023.

Yale professor and principal investigator Noah Planavsky said the contamination has created an obvious need for new tools to help affected farmers, and that the team’s approach offers a path that lets farmers keep working their land while restoring its health. Thompson said the contamination disproportionately hurts small and organic farmers, and that the new method offers them a real way to regain some agency over their own land. The work was supported by Yale Planetary Solutions, Yale Ventures, the Schmidt Family Foundation, and the UK’s Natural Environment Research Council, with co-authors from Yale, the University of Southampton, Georgia Tech, and Brown University.

Journal: Proceedings of the National Academy of Sciences
Article Title: Integrated thermal and phytoremediation of agricultural soils impacted by PFAS
DOI: 10.1073/pnas.2600786123
Publication Date: July 21, 2026

Source: EurekAlert