Biochar: Coral Reef of the Soil

Justin Roberts, MLA '22, describes his journey abroad exploring the powerful potential of using biochar in landscape design.

For students at the University of Washington, discovering their academic and career passions is a journey of exploration, opportunity and learning. Justin Roberts knows this well. Justin is a third-year master of Landscape Architecture student. He spent a quarter abroad in Sweden as part of the  Valle Scholarship & Scandinavian Exchange Program , which funds student exchanges between the UW and Nordic countries. He is also the author of his new book,  “Metabolic Matters: An Urban Designer's Guide to Biochar,”  where he explores how biochar, an incredibly sustainable material that can be made from any organic substance, can be used to tackle some of the most difficult challenges facing humans and ecosystems across the globe. This book was inspired by the many journeys Justin has taken in his life as a student, emerging landscape architect and passionate proponent of adopting more holistically sustainable practices into landscape design. 


Discovering a Passion for Biochar

White man smiling in a button down

Justin Roberts, MLA Candidate '22

Justin’s discovery of his passion for biochar is an amalgamation of the many different opportunities he encountered throughout his personal and educational journey. He describes his background as being interdisciplinary. As an undergraduate student, he received a degree in Science, Technology & Society at the University of Puget Sound, where he studied history and philosophy of science under the lens of environmental policy.

One of the catalysts into his exploration of biochar was learning about how Indigenous peoples in the Amazon region and cultures across the globe used biochar to create rich, fertile soil that people still use for agriculture today.

Biochar is a gift from Indigenous civilizations that figured out how to make really fertile soil and fuel their communities with it

Amazon Rainforest, South America

There is a growing body of research documenting how Indigenous communities in the Amazon region made extensive use of biochar for thousands of years. Justin explains that the layer of fertile soil in the Amazon is extremely thin because most nutrients are immediately incorporated back into living biomass or washed away by the rain. Therefore, people had to come up with a solution to create better soil to produce food for their communities. Biochar became one of the most effective solutions to this problem. Justin explains, “The amazing thing about char is that it has so much surface area, it acts like a sponge for nutrients and microbes, and it becomes a ‘coral reef’ in the soil.” Biochar also doesn’t degrade for thousands of years, meaning communities have been able to utilize its benefits for many millennia. 

“Biochar is a gift from Indigenous civilizations that figured out how to make really fertile soil and fuel their communities with it,” says Justin. While European-borne diseases and other impacts from settler colonialism decimated the populations of these cultures after Spanish explorations in the 16th century, their soil and agricultural legacy remains. Furthermore, biochar is making a comeback among Indigenous communities in the Amazon today as a means of practicing more permanent tropical agriculture—something that also has enormous potential to mitigate the negative impacts of tropical slash-and-burn agriculture around the world. 

Biochar is a carbon-rich material that results from heating up organic matter to between 300 and 800°C with minimal oxygen present. The material is very similar to charcoal and can be added to compost to create permanent structures to host the soil’s nutrients and microbiota. Biochar can be made from any organic material, such as wood, grass and human and food waste. The benefits of biochar are wide-ranging. Biochar is incredibly effective at filtering out pollutants that cause dead zones in watershed ecosystems, supporting the vitality of plant communities, retaining water in the soil and sequestering greenhouse gas emissions from the atmosphere. 

After completing his undergraduate degree, Justin worked as a political organizer and canvass director for just over a year, and then moved on to become a naturalist guide for a local tour company called Evergreen Escapes. There, he facilitated small group tours to places such as Mt Rainier, Olympic National Park and Mt St Helens. During his time as a guide, Justin developed his skills as a storyteller for the interconnected narratives that link the region’s fascinating natural history with the diverse ways that people have inhabited the region for millenia. After gaining valuable experience as a year-round guide in the region's parks, Justin felt the pull to shift his career path towards addressing the rift between people and nature that made visiting National Parks feel like such a necessity. Having been exposed to landscape architecture through friends and family, he decided to explore the option at UW. While biochar was in the back of his mind from his interest in undergraduate school, Justin didn’t anticipate how central biochar would become to his master’s research. 

Wood pellets from sawmill waste can be made into biochar as seen here from the Swedish green roof company  Veg Tech . They use biochar to enhance the soil for their sedum mats while producing heat for their greenhouses and office space.


Valle Exchange

While in school, Justin discovered the Valle Exchange Program. “I heard about the Valle Exchange after the Italy abroad program got canceled due to the pandemic,” says Justin, “I liked how the Valle program lets students do their work independently. I learned that the program allows you to come up with your own research agenda and connect with people abroad who will help you carry it out and get support from UW.”

While searching for a mentor and topic to pursue on exchange, he browsed through research being done at landscape architecture departments at various Scandinavian universities. Justin encountered work on biochar at the Swedish University of Agricultural Sciences (SLU) in Lund, Sweden and decided to reach out. Soon after, he was contacted by Ann-Mari Frannson, a professor at SLU and one of the leaders of a project in Sweden called “ Rest till Bäst ,” which essentially means turning leftover material from ‘waste to gold’ in Swedish. This project brings together landscape architects, biologists, researchers, city operators and administrators to investigate how biochar can revamp urban landscapes, documenting both its uses and benefits. Ann-Mari graciously accepted Justin’s proposal to mentor him and connect his research to her work.

Lund University, Sweden

A few months after his application to the Valle program was accepted, Justin found himself over 4,000 miles away from the Pacific Northwest in Scandinavia. During his time there, Justin traveled throughout Sweden and Finland  interviewing practitioners, visiting key sites of biochar research, and learning more about how landscape architects incorporate biochar into their designs to improve communities and plant health. 

Varvsparken, Malmö

Stockholm

Vellinge

Hyväntoivonpuisto Park, Helinski

Varvsparken, Malmö

Justin was based in a city in southern Sweden named Malmö, where he interviewed researchers  working on a variety of research projects being conducted in the area. One project Justin reviewed was based in Varvsparken, a small urban park in Malmö, where Ann-Mari Frannson and the City of Malmö’s BiodiverCity project led research to examine the impact of biochar on the diameter of trees and their response to stressors like drought as part of an effort to establish a forest ecosystem and enhance the city’s biodiversity. One side of the park’s soil was mixed with biochar and compost, while the other side was left without the biochar mixture. They found that the trees with the biochar mixture had healthier and faster growth and were more drought resistant than trees without it. This project illustrates the powerful impact biochar can have on supporting plant resilience and biodiversity in urban environments.

Stockholm

According to Justin, the pioneering use of biochar in Stockholm acted as a major catalyst for its widespread use in the region. Justin spoke with Björn Embrén, who used biochar to improve the health of urban trees in the city. When Björn was put in charge of the health of the city’s trees in Stockholm, he discovered that nearly all the trees were dead or dying. Björn and his team at the Stockholm Traffic Office (some of whom would later become members of the Rest til Bäst project) worked to pair biochar with structural soils to create new soil types that would support healthy trees and purify the city’s stormwater. They began working with the city to carefully replace the compacted soil around dying trees with new soil composed of macadam rock, biochar and compost and then documented marked improvements in tree health. They also planted new trees in these soils systemically around the city and documented their success rates. 

The project had tremendous results. Trees had greater rates of survival, increased growth and clearly indicated the efficacy of using biochar as a catalyst for low-tech structural soils to improve tree health. Other cities in Scandinavia were inspired to use the tactics demonstrated in the research, kickstarting the region’s biochar economy. 

Vellinge

Justin also ventured to the city of Vellinge in southern Sweden to learn how  Edge , a consulting and landscape architecture firm specializing in blue-green-grey (BGG) infrastructure, renovated parts of the city to improve stormwater management, create more sustainable green spaces that support biodiversity and ecosystems, reduce flooding risk and provide more space for play and safe pedestrian movement. Edge’s design uses a load-bearing porous layer of condensed rock material that is enhanced with biochar to create a structural soil that boosts the ground’s water holding and filtration capacity and improves conditions for plants. Their design utilizes gas exchange pits combined with this structural soil to ensure oxygenation below the ground, a crucial component of healthy soil and plant life. The results of this design demonstrate how biochar as a sustainably sourced carbon structure supports soil communities, assists water filtration and supports thriving plant communities.

Hyväntoivonpuisto Park, Helinski

During Justin’s time in Scandinavia, he spent 10 days in Finland, where he learned about the Carbon Lane project based in Hyväntoivonpuisto Park in the Jätkäsaari neighborhood of Helsinki. The Carbon Lane Project is a co-collaborative effort to offer an opportunity for a variety of stakeholders to research, learn, and provide insight into how to incorporate different strategies and public engagement into urban landscape designs that strive to sequester carbon in their local environments. Researchers utilized a range of biochar infused soils as the primary tactic to sequester carbon. Justin met with one of the lead researchers involved in the project. Justin interviewed him and also met and advised some of his students, who were preparing to do research analyzing the potential for biochar production in Helsinki. He visited the park and CarboFex's biochar production facility, a major biochar producer in Finland and participant in the Carbon Lane project. According to Justin, the final iteration of the design resulted in a park that didn’t meet all initial experimental ideals but provides a valuable insight into the challenges of aligning the research needs with construction timetables and cost limits.

Justin visited many other sites across the region. He says that the Valle Program offered him an incredibly valuable experience as a researcher and graduate student, “It was such a tremendous opportunity to talk and meet with all these people and see all these sites for myself.”


Back to the US: Reflections

Justin says his journey to Scandinavia had a huge influence on him. He emphasizes how much he enjoyed the independence of the program because he was allowed to “step off the regular treadmill” of the traditional course structure of graduate school and think deeper about the projects he researched. Not only was he thrilled to be able to focus on what he was passionate about because of the flexible structure of the learning environment, he also got to improve many skills essential to landscape architecture. Justin earned credit for an independent sketch class, enabling him to devote significant time towards this key reflective and communicative practice in the profession. His ability to invest more time into thinking about his research also allowed him to expand his thinking about biochar as a generative material that connects to broader strategies for circular and regenerative economies. 

South Park, Seattle

To synthesize his work abroad, Justin is participating in a two-quarter long capstone studio course based in South Park in South Seattle along the Duwamish waterway. The South Park community is a diverse neighborhood that has demonstrated incredible resilience and solidarity in the face of challenges resulting from toxins released from the industrial area nearby and pollution and disconnection from highways that bisect the community. Justin’s studio, run by the Landscape Architecture department’s Associate Teaching Professor Julie Parrett, focuses on catalytic landscapes, exploring how landscapes can generate benefits in a way that continually unfold and do so in close coordination with the communities they serve.

Because of biochar’s unique multifunctional properties and production process, Justin believes that the material holds potential for positive and circular economic and landscape processes to emerge in these communities. He hopes to see how biochar can help address some of the toughest issues in South Park, such as reducing exposure to toxins in the soil, enhancing food growing capacity, and cleaning up stormwater running into the Duwamish River.

As an emerging landscape architect, Justin hopes to continue to be able to investigate how biochar can transform degraded soil into a foundation for thriving communities of soil biota, plants and people. After graduation, he plans on journeying back out to the mountains to reconnect with the outdoors and traveling before he starts working. He hopes to give “attention and love to the soil and plant communities” by doing work that unites the needs of people and the functioning of ecosystems as a designer at a landscape design firm in Seattle.


Department of Landscape Architecture | UW College of Built Environments

Justin Roberts, MLA Candidate '22

Biochar is a carbon-rich material that results from heating up organic matter to between 300 and 800°C with minimal oxygen present. The material is very similar to charcoal and can be added to compost to create permanent structures to host the soil’s nutrients and microbiota. Biochar can be made from any organic material, such as wood, grass and human and food waste. The benefits of biochar are wide-ranging. Biochar is incredibly effective at filtering out pollutants that cause dead zones in watershed ecosystems, supporting the vitality of plant communities, retaining water in the soil and sequestering greenhouse gas emissions from the atmosphere. 

Wood pellets from sawmill waste can be made into biochar as seen here from the Swedish green roof company  Veg Tech . They use biochar to enhance the soil for their sedum mats while producing heat for their greenhouses and office space.