Healthy Soil Sounds ‘Like an Underground Rave Concert’ With Clicks, Pops and Crackles of a Vast Ecosystem

If you’ve ever wondered what healthy soil sounds like, a new study has found that it emits the clicks, crackles and pops of worms and ants moving around underground.

Barely audible to humans, the cacophony of sounds is “a bit like an underground rave concert of bubbles and clicks,” a press release from Australia’s Flinders University said.

Ecologists from Flinders made special recordings to show the tumultuous mix of soundscapes made as small animal species interact with their vast, hidden environment.

“Our research team has developed a simple way to use sound to monitor life in the soil, which could help improve soil health worldwide,” said lead author of the study Dr. Jake Robinson, a microbial ecologist with the Frontiers of Restoration Ecology Lab at Flinders University’s College of Science and Engineering, and co-author Dr. Martin Breed, an associate professor of biology at Flinders University, in The Conversation.

Fifty-nine percent of Earth’s species live within these below-ground ecosystems.

“Although still in its early stages, ‘eco-acoustics’ is emerging as a promising tool to detect and monitor soil biodiversity and has now been used in Australian bushland and other ecosystems in the UK,” Robinson said in the press release. “The acoustic complexity and diversity are significantly higher in revegetated and remnant plots than in cleared plots, both in-situ and in sound attenuation chambers. The acoustic complexity and diversity are also significantly associated with soil invertebrate abundance and richness.”

Robinson explained that — as 75 percent of soils on the planet have been degraded — without restoration, underground species face a dire future.

“This figure could rise to 90% by 2050 due to deforestation, overgrazing, urbanisation and other destructive practices,” Robinson and Breed said in The Conversation. “Such degradation poses significant risks, not only to biodiversity but also to the ecosystem services humans rely on, such as food production.”

The study compared data from acoustic remnant vegetation monitoring to land and degraded plots that had been revegetated 15 years earlier, the press release said.

The researchers used a variety of indices and tools in the passive acoustic monitoring of soil biodiversity across five days in the Adelaide Hills of Southern Australia’s Mount Bold region.

“It’s a bit like going to the doctor,” Robinson said, as The Guardian reported. “They put a stethoscope on your chest, take a health check, listen to your beating heart… we’re doing something similar in the soil.”

The research team used a sound attenuation chamber and below-ground sampling device to record invertebrate communities living in the soil, which they also counted manually, the press release said.

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“It’s clear acoustic complexity and diversity of our samples are associated with soil invertebrate abundance – from earthworms, beetles to ants and spiders – and it seems to be a clear reflection of soil health,” Robinson said in the press release. “All living organisms produce sounds, and our preliminary results suggest different soil organisms make different sound profiles depending on their activity, shape, appendages and size. This technology holds promise in addressing the global need for more effective soil biodiversity monitoring methods to protect our planet’s most diverse ecosystems.”

The study, “Sounds of the underground reflect soil biodiversity dynamics across a grassy woodland restoration chronosequence,” was published in the Journal of Applied Ecology.

“Restoring and monitoring soil biodiversity has never been more important,” Robinson said.