Soil, often overlooked, is a dynamic and essential ecosystem teeming with life, according to soil scientist Frank Ashwood's exploration in "The World Beneath Our Feet." Ashwood likens the soil to "the last great unexplored frontier on our planet," a space characterized not only by its inhabitants but also by its distinct sounds.
Soil scientists can assess soil health by listening to the audible activity within it. These recordings capture a "sustained low rumbling sound" generated by plant roots pushing through the earth, alongside noises described as raking sand, creaking like a settling house, and a series of clicks. This sonic landscape is the "underground orchestra of invertebrates"—including ants, beetles, springtails, fly larvae, centipedes, woodlice, and spiders—navigating their subterranean world.
Among the myriad creatures highlighted is the springtail, a tiny but crucial insect for soil health that acts as a busy recycler. These insects possess a remarkable ability to jump up to 100 times their body length, an equivalent leap for a human over a 45-story building.
The importance of decaying organic matter, particularly dead and rotting wood, is also emphasized. While historically cleared away, fallen wood is now recognized as vital, supporting up to 40 percent of all forest organisms. Many gardeners intentionally create log piles to foster this environment.
The book introduces other fascinating soil dwellers, such as a mite species that has reproduced exclusively through parthenogenesis, or virgin birth, for 100 million years. It also mentions the aggressive Asian jumping worm, an extinct ancestor of spiders called a trigonotarbid, and the velvet worm, equipped with "glue-firing cannons" on its head. The Black Forest in Germany is home to the magnificently named Badischer Riesenregenwurm, a giant earthworm that can grow up to two feet long.
Grasslands, especially ancient, unsprayed, and moderately grazed ones, can harbor immense underground life, with some containing "100 tonnes of living biomass per hectare." This density is illustrated by imagining the weight of approximately 15 African bull elephants beneath a standard rugby pitch.
Ashwood discusses the historical shift in global forest cover, from over 80 percent to the current 32 percent. While increased other habitats are not necessarily problematic, he advocates for "agroforestry," or "wood pasture," which integrates trees and thickets within grasslands or crop fields, a practice found in much traditional European farmland.
With at least a third of the world's soils facing moderate to severe degradation, Ashwood stresses the critical need to value soil for the health of nature, wildlife, and humanity's future. "The World Beneath Our Feet" is available from the Mail Bookshop.