Healthy soil is the foundation of life on Earth. It nurtures our crops, regulates water cycles, stores carbon, and sustains countless organisms that keep ecosystems in balance. Yet, this vital resource is under growing pressure, from intensive agriculture, pollution, and climate change, leading to degradation and a loss of biodiversity.

In response to these challenges, researchers in Switzerland and Japan launched The Garden Experiment, a joint initiative exploring how adding compost can reshape the soil’s microbiome and offer insights into restoring healthy, diverse ecosystems. Over the past weeks, about 300 citizen scientists from both countries have taken part in this experiment in their own gardens, embarking on a fascinating journey into the unseen world of microorganisms and their crucial role in soil health.

The project was first conceptualized and developed at the NCCR Microbiomes in Switzerland. Thanks to a fortunate set of circumstances, it took an international turn, evolving into a joint Swiss–Japanese research initiative. This unique collaboration was recently showcased at the Matsudo International Science Art Festival (MISAF) 2025, where science met art to engage a broader audience.

This article will walk you through some of the key milestones of this project, from the launch event, where citizen scientists received their experimental kits, to the art-science festival, which featured an inspiring talk and an exhibition offering a glimpse into the hidden life of microbes.

The Garden Experiment explores an innovative approach to restoring soil health: using microbial transplants from healthy soils to rejuvenate depleted ones. At its core, the project investigates whether introducing a small amount of inoculum or compost, soil rich in microbial life, can shift the microbial community in a new location. This is no simple task: native microbes often outcompete newcomers for space and nutrients. Understanding these dynamics is crucial for developing sustainable strategies to improve soil fertility and resilience.

What makes this experiment unique is its citizen science model. Volunteers across Switzerland and Japan with access to garden soil were invited to participate. Each received soil transplants samples and empty labeled tubes. The process was simple yet scientifically rigorous: mix the soil samples into a 10×10 cm plot of garden soil, leave it for six weeks, then collect the samples from the treated plots and one from an untouched area nearby. Participants mailed their samples back, along with location data.

In the lab, researchers will analyze microbial diversity. By comparing treated and control samples, and aggregating data across all participants, the research teams aim to uncover patterns in microbial colonization and soil recovery. Results are expected in spring 2026, offering insights into how small interventions can make a big difference for soil ecosystems.

[Source: https://nccr-microbiomes.ch/outreach/the-garden-experiment/ ]

The Garden Experiment officially launched in Japan on October 11, 2025, with a kick-off event at Shountei in Tojo Park, Matsudo. Organized by the MISAF Lab and the Science & Technology Office (STO) Tokyo, the event welcomed participants as citizen scientists, introducing the project’s goals and explaining the experimental process. Attendees received their research kits, which included compost samples and tools for soil collection, and learned how their contributions would help study the impact of compost on soil microbiomes.

The program opened with Yoko Shimizu (MISAF Lab), who presented the project’s objectives and highlighted both the scientific and cultural significance of the project drawing parallels with other transformative citizen science initiatives worldwide. Adding an international perspective, Anne-Mai Do (Science & Technology Office Tokyo, Embassy of Switzerland in Japan) shared the backstory of this Swiss–Japanese collaboration, highlighting the shared commitment to advancing science through public participation. Attendees were also introduced to the key stakeholders driving the initiative (see “Partners” section at the end of the article). This was followed by an engaging talk from Dr. Ryo Miyazaki (AIST Microbial Systems Research Team), the lead researcher on the Japanese side, who offered a deep dive into the fascinating world of microorganisms. Participants explored microbial diversity, the challenges of studying life invisible to the human eye, and the cutting-edge techniques researchers use to overcome these hurdles.

The event concluded with a hands-on workshop led by Tomoko Sekiguchi (MISAF Lab). Citizen scientists learned the step-by-step process they would follow in their own gardens. After the distribution of Garden Experiment kits, participants returned home equipped with compost samples and clear instructions.

While participants were waiting for the six-week experiment period to pass, the project reached another important milestone: its presentation to a broader public at the Matsudo International Science Art Festival 2025. Held from October 24 to 26 at the beautiful Tojo-tei House in Matsudo, the festival featured a rich program of exhibitions and talks from diverse international art-science projects, including The Garden Experiment, which added a unique dimension to the festival thanks to its combination of citizen science and microbiome research.

Exhibition

As a highlight of MISAF 2025, the satellite exhibition “INVISIBLES: The Hidden Life of Microbes” invited visitors to explore a world that is everywhere yet rarely seen, the fascinating world of microorganisms. Co-created by the Musée de la main UNIL-CHUV and the NCCR Microbiomes, this unique exhibition bridges science and art to make the invisible visible.

For its Japanese edition, the exhibition featured an exclusive section on The Garden Experiment, showcasing how over 300 citizen scientists in Switzerland and Japan are helping uncover ways to restore microbial diversity in soils. This integration highlighted the festival’s mission: blending creativity, sustainability, and innovation to inspire a deeper connection between humans and the planet.

The full version of the exhibition remains on display at the museum in Lausanne, Switzerland, with its run recently extended until August 30, 2026. If you are planning a visit to Lausanne, do not miss the chance to experience it in its entirety!

Talk event

During the festival, the Garden Experiment took center stage in a special talk titled Switzerland × Japan: International Citizen Science Art Project. The session highlighted the project’s unique blend of scientific inquiry and cultural exchange, illustrating how microbiome research can intersect with citizen participation and artistic interpretation.

The panel featured Prof. Jan Roelof van der Meer (University of Lausanne), the lead researcher on the Swiss side, who joined online from Switzerland in the early morning hours. He was accompanied by Yoko Shimizu and Tomoko Sekiguchi (MISAF Lab) who shared insights from the Japanese side of the collaboration. The panel was moderated by Anne-Mai Do (Science & Technology Office Tokyo, Embassy of Switzerland).

The discussion emphasized why soil health matters globally, the role of microbes in sustaining ecosystems, and how compost can help restore biodiversity. Beyond science, the talk explored the value of involving citizens, not only to collect meaningful data but also to foster awareness and encourage a shift toward planetary thinking. By connecting art and science, the session invited participants to see soil as a living system and humans as part of a much larger ecological network. This interdisciplinary approach reflects the project’s ambition: to inspire curiosity, collaboration, and action for a healthier planet.

Curious to hear the full conversation? Watch the complete talk here: https://www.youtube.com/live/7CrEY0MFgvA?si=dZgbUB4hHPW_M3NK

The Garden Experiment is far from over, what comes next is even more exciting! The project has now entered a crucial phase: collecting soil samples from citizen scientists and sending them to the lab for DNA extraction and sequencing. Once the sequencing is complete, researchers will dive into data analysis and interpretation, comparing results from Switzerland and Japan to uncover patterns and insights into how soil transplants can influence soil microbiomes in gardens. These findings will form the basis of a scientific publication, contributing valuable knowledge to the global conversation on soil health and biodiversity.

But the journey does not end there. In true art-science spirit, the research will take on a new life, transforming data into an artistic work that will be showcased at the Matsudo International Science Art Festival 2026. This final chapter will celebrate not only the science but also the creativity and collaboration that made this project possible.

Stay tuned, the story beneath our feet is just beginning!