Earth Matters

Recently, I’ve been spending quite a bit of time thinking about soil. When you’ve spent over three years thinking about ants, thinking about soil is a natural, very small, step. Most northern ants live in the ground. They tunnel and dig. In many places they can be as important for soil as earthworms. Once you’ve crouched down to the ground to get up close and personal with the ants (or in my case, sprawled on your stomach), the soil is hard to ignore. But like many people, I’ve always taken it for granted. I hadn’t thought much about soil, besides when I dragged 50 liters of soil into my apartment to fill my increasing collection of plant pots.

But soil matters. Earth matters, as Richard D. Bardgett’s book has taught me. As a scientist, I sometimes feel guilty for reading the popular science books and not the scientific papers in journals. But honestly, after a long day at the office, picking up another scientific paper is harder than cracking open a book.

Bardgett first sent me down memory lane of digging holes in the ground during my first year of biology (2008) to characterise soil profiles. My first ‘wow’ moment came when I learnt the rate of soil formation is around 0.1 millimeters a year. So if you dig a 1 meter hole, you might be going back 10,000 years. In hindsight, this explains why stone age tools are often discovered when fields are ploughed, they really aren’t buried that deep.

The most exciting parts of the book were on the relationship between soil and biodiversity and between soil and humans. In a handful of soil, you might find billions of organisms among thousands of species. It’s even estimated that soil contains 25 % of the living diversity on earth. It’s therefore to then read that, in Europe, 500 square kilometers of land are sealed by impermeable material (like concrete) every year. That’s an area almost six times as large as Copenhagen, 2.5 times Stockholm, approximately the same size as Oslo. You get my point.

Besides containing a wealth of, often overlooked, biodiversity, soil delivers a number of ecosystem services benefiting humans. The most obvious is food, both for us and for the animals we later consume, but also all the other things we get from plants: lumber, paper and textiles, to name a few. Soil also plays a key role in regulating nutrient and water availability. It is the third largest carbon store and, depending on how we treat it, may act as both a source and sink of greenhouse gasses. As his chapter on soil and war (if not the entire book) makes painfully obvious, we have not treated soil well. But I found the second world war “Dig for Victory” campaign truly inspiring. Lawns, flowerbeds and sports pitches were converted into allotments. 1.4 million people in Britain dug up their lawns to grow food. A small miracle, considering how much brits love their gardens. Perhaps a future campaign could focus on how to best optimize soil conditions for biodiversity and climate. One can dream.

Entire civilizations have risen and collapsed through the management of soil. Yet I agree with Bardgett, soil is an underappreciated subject. Hopefully the tides are turning. 4.5 stars. A few repetitions here and there (and not enough about ants), but a great awakening to the importance of soil.

Rating: 4.5 out of 5.
Soil and the city: View across the ground in Frederiksberg Garden, Copenhagen, Denmark. 09.10.2020

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