EVERSON — A slurry of shredded paper may become the next alternative for mulching in agriculture.
Cloud Mountain Farm in Everson is working on a new approach to mulching with the support of a grant from the Sustainable Path Foundation and Organic Valley.
This 20-acre nonprofit farm focuses on organic fruit production, from apples to kiwis.
“We first heard about hydromulch through our organic inspector who was familiar with work being done at Washington State University,” field manager Jacob Mills said.
As Mills trudged through the grass alongside fruit program manager Maia Binhammer, both stopped at a soil bed, pointing to the layer of hardened mulch sprayed two weeks prior.
This gray-white colored coating is derived from a mixture of cellulose, water and tackifier — a binding agent that helps the mulch cling to the soil. This triad of compounds forms hydromulch, a recycled paper-based alternative to plastic mulches.
Commonly, plastic film that many conventional and organic farmers have relied on is spread out over the ground to suppress weeds, retain water and improve soil health, with the goal of increased crop production. Plastics are used extensively in farming, from plastic-coated seeds to mulch film.
But when this type of mulch is exposed to environmental factors such as sunlight and dryness, the material can break down into microplastics, contaminating the soil and posing a potential health risk for human consumption.
A common misconception is that organic agriculture doesn’t use plastic for mulching, explained Binhammer, and while organic farmers will often work with biodegradable plastic, this plastic material has yet to receive approval for organic production.
Binhammer added that an alternative may just be what farmers need to combat weed and soil moisture loss, two critical factors to keep in mind as farmers head into the summer’s dry season.
Washington State University associate professor Lisa DeVetter leads the research on hydromulch, and also works with other colleges such as North Dakota State University and Montana State University.
In Montana, their team examined various cellulose sources in combination with different proportions of tackifier to understand how the material could be tested on fruit crops such as strawberries.
Cloud Mountain had initially contacted WSU about the project, as the university has a history of working with the farm.
“We looked at it as a great opportunity to partner with a really important leader in Northwestern Washington,” DeVetter said.
After the university started running small trials, the farm became a partner shortly after to test out the mulch alternative on a larger scale — “sorting out the kinks,” as Mills put it.
Once the recycled paper is fully shredded, a machine pumps out a layer of paper mache, lining each row.
Unlike plastic mulch that is laid down before a seed is transplanted, hydromulch takes on a liquid form, allowing for an easier application among different bed shapes and sizes.
While an alternative to conventional plastic mulch is what farm managers such as Mills and Binhammer strive for, both noted a few caveats as to how the hydromulch is sourced.
“Something we’ve encountered since we’ve started this project is that finding a source of clean, recycled shredded paper that meets the criteria for organic is quite a bit more complicated than we initially anticipated,” Mills explained, referring to PFAS, or “forever chemicals.”
This large group of synthetic chemicals are resistant to heat, water, oil and grease and are found in many plastics — but these compounds may also be found in recycled paper.
Initially they received a large volume of shredded paper from Spring Fill — a recycled paper manufacturer based out of Illinois — but discovered that it was too sturdy and didn’t break down in water fast enough for application.
“Once this tears and shreds, we’ve got to put it in the dumpster, there’s not a recycling option,” Binhammer said, waving to the plastic film beneath her.
The idea is that with an alternative such as hydromulch, the material can be worked back into the soil, adding organic matter.
The equipment that both Binhammer and Mills used is built for hydroseeding, which sprays slurry on the seeds themselves. The tank is filled with water, slowly feeding paper into the pump where the material is pulped until a slurry forms, or as Mills described, an “almost baby food-like texture.”
This application process is a lot faster than the one for plastic, aside from the mixing beforehand.
The farm also has soil moisture units installed to monitor water retention levels each week.
In an area prone to flooding, Binhammer noted how farmers have had issues in the past with agricultural runoff, where plastics are moving out and into nearby streams and waterways.
Ultimately, Cloud Mountain Farm wants to generate information to share with other growers.
“Hopefully we can create some really useful tools to help people evaluate the technology from here on out,” Mills said. “We’re just trying to act as a bridge between the research trial and production side of things.”
Olivia Capriotti is a Dow Jones summer news intern, specializing in data journalism. Reach her at oliviacapriotti@cascadiadaily.com.
