What a Hot Air Balloon Taught Me About the State of Our Soil

A couple of years ago I was drifting over the British countryside in a hot air balloon, looking down at the patchwork of fields below, when I noticed something unusual. Huge rings were in the grass beneath us. I asked the pilot what they were.

“Fairy rings,” he said. “You don’t see large ones much anymore.”

These enormous rings are formed by fungi spreading slowly outward underground over many years. As the fungus grows, it changes the availability of nutrients and water in the soil, often creating circles of unusually green grass, bands of stressed vegetation, or rings of mushrooms above ground.

Some fairy rings are formed by fungi associated with plant roots, while others are caused by decomposer fungi feeding on organic matter in the soil. The rings themselves are not especially rare, but very large rings are often associated with long-established grassland that has remained relatively undisturbed over time.

What stayed with me was not simply the rings themselves, but how little of the landscape below appeared untouched. Ancient meadows and unimproved grasslands, habitats once widespread across Britain, are now increasingly scarce. And that moment has stayed with me ever since.

Why Soil is Everything

Soil at a Green Up Britain planting site - biologically active, reasonably fertile for woodland species, and not severely compacted.

We talk a lot about trees, wildflowers, and wildlife, but underneath all of it is something even more fundamental: soil. A single teaspoon of healthy soil can contain billions of microorganisms. Bacteria, fungi, nematodes, protozoa, insects, and earthworms all play a role in breaking down organic matter, cycling nutrients, storing carbon, and maintaining the structure that healthy ecosystems depend on.

Healthy soil is the foundation of life on land. Without it, ecosystems struggle, food production becomes harder, and landscapes become less resilient. And right now, many soils are under pressure.

Decades of intensive farming, repeated ploughing, overuse of synthetic fertilisers, heavy pesticide use, and soil compaction have degraded soil structure and reduced biodiversity in many parts of Britain. When soil loses organic matter and structure, it becomes far more vulnerable to erosion by wind and rain. And once topsoil is lost, it can take centuries to rebuild naturally. Estimates vary, but forming just 3 cm of topsoil may take from around 100 to over 1,000 years depending on climate and conditions.

The Problem of Compaction

Another major threat to soil is compaction. When heavy machinery repeatedly crosses land, or when livestock are concentrated too densely for too long, the air spaces within the soil become compressed.

Those spaces matter enormously. Plant roots rely on them for oxygen, water movement, and access to nutrients. Compacted soils absorb water less effectively, drain poorly, and make it harder for roots and soil organisms to thrive.

What Actually Helps

The encouraging thing is that many of the solutions are already well understood.

Practices such as crop rotation, reduced tillage, cover cropping, organic matter restoration, carefully managed grazing, and reducing unnecessary chemical inputs can all help improve soil health over time.

Well-managed grazing systems, where animals are moved regularly between areas, can help maintain grassland diversity and reduce some of the damage associated with overgrazing or compaction.

One widely discussed example is Knepp Estate. Once run as an intensive farm, the estate shifted toward a large-scale rewilding approach using free-roaming grazing animals. Over time, biodiversity and soil recovery have become central parts of that story.

The Role of Trees in Soil Health

One of our saplings surrounded by leaf litter on woodland floor.

Trees also play an important role in protecting and rebuilding soils. Their roots help stabilise the ground and reduce erosion, while creating channels that improve water infiltration and soil structure.

Leaf litter and decaying wood return organic matter to the soil, feeding fungi, microbes, and invertebrates. Over long periods, this process helps build richer, more biologically active soils.

Trees do not simply grow in healthy soil, they also help shape and maintain it.

Why This Matters to Green Up Britain

When we plant trees and wildflowers, we are not only thinking about what grows above the ground, but also about the living system beneath it. Healthy soil improves resilience, supports biodiversity, stores carbon, and gives ecosystems the best chance to thrive long into the future. Which is why at Green Up Britain, we don’t see tree planting as a simple gesture.

Every tree planted is an investment not only in the land beneath it, but in the generations that will one day depend on that soil. The fairy rings are still out there, quiet reminders that healthy soils are living systems, resilient and capable of renewal when we choose to care for them.

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