Sounds of the Underground

EARTH'S SYMPHONIES INDICATE SOIL HEALTH

Soil is the foundation of life on earth, supporting a rich variety of organisms that help recycle nutrients, filter water and lock away carbon. Yet a staggering 75% of soils around the world are severely degraded due to overuse, erosion, and pollution. If you look closely at a handful, through a microscope, you will find it teeming with life and almost alien life-forms! And what you can't see, you can now hear, or at least Dr Jake Robinson and his team at Flinders University in Australia can, as they've been tuning in to the sounds made by these living organisms, emanating from soils underground.

'Eco acoustics', using acoustic sensors to record sound, has to date proved to be an efficient way of monitoring both elusive and protected species from birds to amphibians, invertebrates to crustaceans and fish. Now Dr Jake and his team have demonstrated that it can also help monitor soil biodiversity in different forest restoration contexts, including UK temperate and Australian grassy woodlands, where their studies took place.

Using 'Eco acoustic' tools, they compared live recordings from pristine vegetation with those from degraded plots and land that was revegetated 15 years ago and discovered that the greater the acoustic complexity and diversity of the monitored 'songs', the more invertebrate abundance and richness, and the better the soil health. Soil full of worms had low bubbly sounds, while lighter, six-legged ants made frequent higher-pitched clicks. Millipedes legs apparently make little tapping sounds, whereas the snail's 'glide' was more soft and slimy.

Whilst the effectiveness of using Eco acoustics could make it easier for researchers, conservationists and farmers to find soil degradation there is hope they will also be able to fix it as Dr Jake's research has found playing certain sound frequencies can speed up growth of fungi and bacteria that fend off plant diseases and in the future playing diverse soundscapes of healthy soil back into degraded land could activate helpful fungal growth and rejuvenate it.

Writing in the British Ecology Society's 'Journal of Applied Ecology' on 15th August 2024 they said, "Our results provide new support that Eco acoustics can help monitor soil biodiversity ...This technology holds promise in addressing the global need for effective soil biodiversity monitoring methods and protecting our planet's most diverse ecosystems."

You can read their full report HERE.