By Will Shenton, featuring Julia MaCray, Vermicompost Intern circa 2022
The soil beneath our feet may not often catch our attention, but keeping it healthy can have major impacts on climate change and the overall sustainability of our food production system. A new study of agricultural practices at the UW Farm, led by recent College of the Environment graduate Julia Macray and Professor of Earth and Space Sciences David Montgomery, demonstrated that even relatively small changes to the ways we farm can help restore soil health and sequester carbon from the atmosphere.
“The UW Farm is doing really incredible work, and some very simple agricultural practices have done a lot to improve its soil health,” said Macray, who completed the work as an undergraduate in the Department of Earth and Space Sciences. “It’s an example of the potential for climate remediation and carbon sequestration on a small scale in an urban environment.”
Farming for Topsoil
The study focused on the health of topsoil at the UW Farm, a 1.5-acre student-powered urban farm and educational facility located on what used to be a massive dumping site and landfill. The researchers measured changes to the topsoil’s thickness as well as the overall amount of organic matter and carbon that it contained over the 20-year period since the farm began operations. Thicker topsoil with more organic matter is generally healthier and promotes better crop growth, while sequestering carbon in the soil keeps it out of the atmosphere and can help slow the process of climate change. Healthy soil is also less prone to erosion, and can help control flooding.
“The topsoil is where you get most of the microbial and fungal activity in the soil, and that’s where plant roots are getting all their nutrients,” Macray said. “Topsoil is really important for plant health and soil health in general, and a lot of current agricultural practices will fully erode the topsoil over time.”
Macray found that, under the UW Farm’s regenerative practices, topsoil thickness increased four-fold over the 20-year study period — growing at a rate of just under 1 centimeter per year. Soil organic matter increased as well, but was more variable year to year.
“What Julia’s research showed is that at the UW Farm, they turned a garbage dump into really productive soils in about 20 years,” Montgomery said. “That’s screamingly fast, especially from a geological perspective.”
From Landfill to Flourishing Farm
Located in the Center for Urban Horticulture, near the Union Bay Natural Area on UW’s Seattle campus, the UW Farm sits on land that was once the Montlake Dump, an active landfill until 1966. After significant remediation and restoration work to place a cap of gravel and soil on top of the landfill, the farm broke ground on its first plots in 2002. Given the history of the site, regenerative practices were essential for turning it into productive land.
“There’s no universal agreement on a definition of regenerative agriculture, but I like to think of it as farming practices that can rebuild soil health and fertility,” Montgomery said. “That basically translates into increasing or maintaining soil organic matter and cultivating beneficial life in the soil that enters into symbiotic relationships with crops.”
“There’s no universal agreement on a definition of regenerative agriculture, but I like to think of it as farming practices that can rebuild soil health and fertility,” Montgomery said. “That basically translates into increasing or maintaining soil organic matter and cultivating beneficial life in the soil that enters into symbiotic relationships with crops.”
Modern agricultural practices, especially at industrial scales, are notorious for leaving the soils they use in bad shape. Heavy use of tilling, pesticides and herbicides, and crop monocultures tends to extract nutrients from the soil without replacing them, and kills off the insects and microorganisms that turn organic waste into the stuff plants need to grow. When the topsoil is fully eroded, the results can be catastrophic — like the Dust Bowl across the Great Plains in the 1930s.
The UW Farm takes a different approach. Instead of heavy tilling, they utilize low- and no-till methods which help maintain beneficial fungal networks in the soil. Instead of leaving fields bare in the cooler months, they grow cover crops, such as legumes, that fix nitrogen and other nutrients. Instead of pulling weeds from their plots, they smother them with tarps and let them decompose in place, allowing their nutrients to be recycled. Instead of using chemical fertilizers, they augment their soil with compost, natural soil amendments and fertilizer produced by by earthworms in the farm’s vermiculture bins. And instead of a monoculture, they rotate their crops through different plots of land to ensure the soil doesn’t become deficient in specific nutrients.
“The combination of all of these practices led to that increase in topsoil depth and organic matter that we’re seeing,” Macray said. “There’s a good amount of qualitative evidence that this works, and now we’re getting some numbers to support it.”
A Model for Small Farms
Macray acknowledges that these are preliminary results at a relatively small scale, but sees this study as part of a growing body of research that is helping to shift the narrative about regenerative agriculture.
“People are talking about this more than they did just a few years ago, and consumers especially are becoming more aware of it,” she said. “It’s great to see more small farms using these practices to improve soil health and sequester carbon.”
Montgomery is similarly optimistic.
“This research shows that we can restore the soil faster than we can damage it,” he said. “That’s big news in terms of thinking about the future of agriculture.”
Discard stems, then slice mushroom caps into strips and set aside.
Cook aromatics and mushrooms
Heat a generous glug of olive oil in a pot on medium heat. Add garlic, scallions, and sweet onion and cook for a couple minutes until fragrant and the onions are semi-translucent
Add the sliced mushrooms in and continue to cook for 5 minutes, stirring often until they shrink and have slightly browned.
Make congee
Once the mushrooms have wilted, add in chicken broth, sake, miso, kosher salt, brown sugar, white rice and give it a mix to combine.
Bring the entire pot to a boil, then bring the heat down to low to reduce to a very gentle simmer. Cover with a lid and cook for 1 hour (stir frequently and scrape the bottom every 10 min so it doesn't burn on the bottom) until the water has reduced and the consistency resembles a creamy porridge.
After an hour, remove lid and add heavy cream. Mix until combined, then ladle into bowls and add extra scallions and sesame seeds. Enjoy warm!
The UW Farm donates regularly to the UW Food Pantry. During peak season we also donate to nearby food banks. The links below are resources to help you or someone you know with food access.
Every year, we have the capacity to grow more food and increase our educational and research program at the UW, but not without your support. Every contribution goes to work immediately, helping us better serve students. Your support can sustain our momentum and help seed new opportunities for student internships, academic work, and future growth. Please consider making a gift to the Farm online
The Weekly Dirt is produced once a week by the University of Washington Farm, a program of the UW Botanic Gardens, School of Environmental and Forest Sciences, College of the Environment. It is published nearly year-round for educational purposes and the majority of the content is written or contributed by students and farm staff.
This issue's contributors:
Managing Editor: Siffre Tooth, UW Farm Food Security Lead '23-24
Around the Farm: Julia MaCray, previous Vermicompost Intern '22 Contributing Editors: Perry Acworth, Farm Manager; Siffre Tooth, UW Farm Food Security Lead '23-24 Photo Credits: Perry Acworth. Other photos retrieved from the internet and noted in sections
“The UW Farm is doing really incredible work, and some very simple agricultural practices have done a lot to improve its soil health,” said Macray, who completed the work as an undergraduate in the 
“The topsoil is where you get most of the microbial and fungal activity in the soil, and that’s where plant roots are getting all their nutrients,” Macray said. “Topsoil is really important for plant health and soil health in general, and a lot of current agricultural practices will fully erode the topsoil over time.”
“There’s no universal agreement on a definition of regenerative agriculture, but I like to think of it as farming practices that can rebuild soil health and fertility,” Montgomery said. “That basically translates into increasing or maintaining soil organic matter and cultivating beneficial life in the soil that enters into symbiotic relationships with crops.”
Instead of leaving fields bare in the cooler months, they grow cover crops, such as legumes, that fix nitrogen and other nutrients. Instead of pulling weeds from their plots, they smother them with tarps and let them decompose in place, allowing their nutrients to be recycled. Instead of using chemical fertilizers, they augment their soil with compost, natural soil amendments and fertilizer produced by by earthworms in the farm’s 
