Underground orchestra by tiny creatures is a sign of healthy soil, finds study

New research from Flinders University in Australia suggests that healthy soil has a distinctive soundtrack of its own – the crackles, pops, and clicks of ants and worms bustling around underground. These sounds made by insects and other small creatures, recorded using microphones placed in the ground, may serve as valuable indicators of biodiversity and soil health.

Scientists at Flinders University are using a new method to check soil health by listening to the quiet sounds made by insects and other small creatures underground. The team found that land filled with plants and tiny animals produced a diverse array of underground sounds, while cleared land emitted bland white noise.

Dr. Jake Robinson, an ecologist involved in the study, explained the analogy, “It’s a bit like going to the doctor. They put a stethoscope on your chest, take a health check, listen to your beating heart … we’re doing something similar in the soil.”

This innovative method could significantly enhance the ease with which researchers, conservationists, and farmers detect and address soil degradation.

The importance of soil biodiversity

Soil is crucial for sustaining life on Earth, housing more than half of the planet’s species, and serving as the source of nearly all food production. However, according to UNESCO, over 75% of soils worldwide are degraded . “Restoring and monitoring soil biodiversity has never been more important,” emphasized Dr. Robinson.

Invertebrates such as insects and worms play a critical role in building up soils, improving their nutrient content, and preventing erosion. Their presence in the soil creates a variety of sounds that indicate soil health. For example, soil teeming with worms produces low bubbly sounds, while lighter, six-legged ants generate frequent higher-pitched clicks.

“A millipede has lots of tiny legs, and they make little tapping sounds, whereas the snail has a more slimy glide sound,” Robinson described .

To capture these sounds, scientists use microphones that pick up vibrations from the soil and amplify the recordings by 20 decibels. Researchers must move 20 meters away and stand in silence to avoid creating any confounding sounds.

“You have to stay super quiet, obviously, because you don’t want to create any confounding sounds,” Robinson noted.

A new era of soil health monitoring

The study reviewed hundreds of hours of recordings from 240 locations around Mount Bold in South Australia, near Adelaide. This research builds on earlier studies done in the UK.

It confirms that the acoustic method is just as effective as traditional ways of monitoring soil health. These traditional methods often include costly DNA testing or more invasive techniques, such as digging up soil or setting traps for small creatures.

Dr. Vanessa Pino, a soil scientist at the University of Sydney, welcomed the new approach, stating, “It requires a lot of effort to be sampling and counting invertebrates, so we’re always after ways to infer information in a more straightforward way.”

The acoustic method is not only cheaper and less invasive but also opens the door to backyard diversity testing. “We’re trying to democratize it, so everyone can just buy their own little recorder and microphone,” Robinson added.

Future applications and innovations

Robinson’s research indicates that audio technology might even improve soil health. His forthcoming research suggests that playing certain sound frequencies can accelerate the growth of fungi and bacteria that protect plants from diseases.

This innovative approach could see the diverse soundscapes of healthy soil played back into degraded land to stimulate beneficial fungal growth and rejuvenate the Earth.

The implications of this study extend beyond academia and agriculture. By harnessing the power of sound, researchers can develop new methods for soil conservation that are both accessible and effective.

The future of soil health monitoring may soon be within the reach of anyone with a microphone and a passion for environmental conservation.

The research was published in the Journal of Applied Ecology .