This past week I read an amazing fact, so amazing that I had to verify it by looking at other sources. The fact: One teaspoon of soil from a healthy forest floor contains more living organisms (bacteria, fungi, protists, and nematodes) than there are humans on Earth. And most of the species in that teaspoonful have never been named or described.
I first read this at the Times of India this week. But the actual research quoted in the article is from 2022. Christine Sprunger, an Assistant Professor of Soil Health at Michigan State University has been studying soil health for years, and has famously argued that "a teaspoon of soil contains more life than there are humans on Earth".
Unfortunately, the important words are "healthy soil". Christine Sprunger, as well as many other scientists, point out that we humans are degrading soil quality throughout the world. Main things degrading soil quality are: land conversion, climate change, loss of biodiversity, deforestation, farming practices that disturb the soil in a negative way (tillage, reduced organic matter inputs, pesticides, pollution, nitrates).
One example of serious soil degradation with terrible consequences was the Dust Bowl in the US. Yes, we need healthy soil!
Excerpts from an Oct. 2022 interview with Christine Sprunger. From Open Access Government: Deteriorating soil health: ‘A teaspoon of soil contains more life than there are humans on earth’
...I think it is first effective to define soil health. The Natural Resources Conservation Service, a branch of the United States Department of Agriculture, defines soil health as “the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans”. Thus, on a global scale there are numerous factors that could potentially threaten these living components, depending on where the ecosystem is.
Almost every country on planet earth has experienced a period in history where soils were poorly treated, which caused grave consequences for food security. In the United States, the Dust Bowl is likely the most prominent example, whereby the removal of native vegetation and intensive agricultural practices led to historic losses in topsoil that were then further exacerbated by a prolonged drought during the Great Depression. Many farmers had to abandon farmland and move west. The Dust Bowl led to immense poverty in the Midwest.
These two examples demonstrate the importance of soil health and soil organic matter, which we can think of as the foundational building blocks of topsoil.
Excerpt from August 26, 2026 Science Blog: A single teaspoon of soil from a healthy forest floor contains more living organisms — bacteria, fungi, protists, nematodes — than there are humans on Earth, and most of the species in that spoonful have never been named or described
The teaspoon comparison is memorable because it compresses an ecosystem into something that fits between two fingers. Soil organisms cycle nutrients, decompose waste, influence carbon storage, stabilize aggregates and interact with plant roots. Those functions depend on communities, not merely on the presence of isolated species.
Pick up a handful of soil from beneath fallen leaves and it feels cool, granular and faintly earthy. Within its pores are organisms feeding, competing, reproducing and reshaping their surroundings at scales too small to see.
Many of those organisms still lack species-level names, yet their work continues every hour beneath the forest. The teaspoon is not simply crowded with life. It is a small working piece of the ecosystem above it.