TURNER, Ore. — In 2017, Kathy Bridges and her husband, Ken Dunder, leased out land at their Santiam Valley Ranch to a hemp grower, but the cannabis market collapsed three years later and the farmer fled, leaving behind row after row of polyethylene sheeting in the field.

The plastic fell apart as the couple tried to pull it from their certified organic soil.

Faced with adversity, they responded with curiosity and a can-do attitude. After all, they weren’t just farmers, they were also scientists, and here was an opportunity to solve a big problem for agriculture.

“This was a horrible situation, but we’ll turn it around and learn a lot from this,” Bridges said they decided.

Research on biodegrading polyethylene at their property may help farmers and ranchers deal with similar pollution, including microplastics that get into the ground.

Plastic problems

Thin layers of polyethylene are placed around crops to control evaporation, increase soil temperature and minimize weed growth.

“It’s all over the planet. Everyone is using it,” Bridges said.

But the benefits come with consequences. The plastic “fractures” as it ages and can contaminate soil, reducing ventilation and water permeability, altering microbial communities and hampering root health and overall plant productivity.

“Everything relies on the soil,” Bridges said. “When you alter the soil, things can’t function correctly, and we’ve altered the soil a lot.”

Oregon State University assistant professor Gerry Presley estimated that U.S. growers use more than 50,000 tons of new polyethylene film every year.

It’s the most widely used plastic mulch in the country, but takes hundreds of years to break down on its own.

“If you don’t replace it on a regular basis, that stuff will get brittle real fast. It gets integrated with the soil pretty quick,” Presley said.

“This is probably an issue wherever plastic films are used in agriculture,” he said.

Developing a plan

Dunder, whose expertise was chemical engineering, and Bridges, with a zoology background, developed a plan to break the tight carbon bonds in polyethylene using an ultrasonic system and identify fungi that could digest the modified plastic.

The farmers teamed up with Presley and OSU and secured a four-year, $500,000 grant from the USDA National Resources Conservation Service in 2022.

Doctoral student Leon Rogers has identified two isolates of fungi interacting with polyethylene pieces at Santiam Valley Ranch.

One of the isolates penetrates the plastic, Presley said.

Researchers are also getting closer to breaking down the polymer so fungi can digest it.

They are working with Freres Lumber Co. of Lyons, Ore., to apply biochar to test plots and determine if that spurs additional fungal activity.

Biochar, which is carbon produced by burning wood at high temperatures in a low-oxygen environment, also works as a filter and captures pollutants.

“It may be a way for us to prevent the spread of microplastics into neighboring environments,” Presley said.

That’s important, since Santiam Valley Ranch includes 19 ponds that provide bird habitat.

About the ranch

The ranch includes about 150 acres, and Bridges raises sheep and hosts a duck hunting club, visits from ornithological organizations, wetland workshops and guests in a farmstay rental.

A fish propagation section of the business, Santiam Valley Aquaculture, has been passed down to Bridges’ son, Luke Fitzpatrick.

Bridges and Dunder placed nearly 100 acres of their property into wetlands reserve through an NRCS program in 2012.

Fitzpatrick, another neighbor and the Confederated Tribes of Siletz Indians also put land into conservation reserves, creating a swath of 800 contiguous acres in habitat restoration.

Though Dunder died in 2023, Bridges remains committed to Santiam Valley Ranch.

“I’ve only farmed for 44 years,” she said.

Age: 72

Occupation: Farmer, owner of Santiam Valley Ranch

Family: Three grown sons, late husband Ken Dunder

Education: Bachelor’s degree in zoology and a master’s degree in resource economics from Utah State

Fun fact: Bridges was the first woman hired for field research by the Utah Division of Wildlife. Among other work, she studied Abert’s squirrels.