Opinion: What matters most lies invisible beneath our feet

We humans often have the impression that plants are what feed us. And that’s certainly true to some extent. But there’s a missing ingredient, an important and fascinating variable, often left out of the equation.

That variable, out of sight beneath our feet, is soil.

The soil feeds what feeds us. It constitutes, both literally and figuratively, the foundation of our health and life on Earth. And yet, we know so little about it.

As we celebrate World Soil Day, we invite you to learn more about this living, nourishing heritage home to a quarter of the planet’s biodiversity.

A BIODIVERSITY 'PARTY'

Let’s start with some Soil Science 101: mineral soil comprises approximately 45 per cent mineral particles, 20 per cent air, 30 per cent water and 5 per cent organic matter, and provides plants with the nutrients they need to grow. For plants to absorb these nutrients, the soil must be teeming with a diversity of living organisms – mostly invisible to the naked eye.

Living soil is healthy soil, where the iconic earthworm is assisted in its labour by wood lice, centipedes, arachnids, ants, springtails, mites, nematodes, protozoa, fungi and bacteria – a dizzying array of organisms (and sure to give you a great score in Scrabble). And that’s just a partial list! These exotically named fauna species perform a colossal engineering feat, essential for soil fertility: they structure and aerate the soil while decomposing organic matter into absorbable nutrients such as azote, phosphorous and potassium. These are the nutrients plants and animals (including humans) need to survive.

A single gram of soil can contain several million bacteria from thousands of different species, 95 per cent of which remain unidentified to this day. That shows how much science still has to learn about the biology of living soils.

But the science is clear: over 30 per cent of the world’s soils are in poor or very poor health. This degradation threatens to reduce agricultural output by 10 per cent by 2050.

HEALTHY SOILS ARE A POWERFUL SOLUTION

In the face of the climate and biodiversity crises, it is essential that we deploy solutions that meet the needs of the 10 billion humans expected to trod the Earth by 2050. One tried and tested avenue is to eschew intensive agriculture in favour of regenerative practices, which use the full potential of soils and can help solve various social, environmental and economic issues.

A healthy soil gains organic matter and thus sequesters more CO2. This makes it an ideal carbon sink in the fight against climate change.

With this increased organic matter and the work done by fauna and microorganisms, the soil also becomes better layered and can act like a sponge. It can absorb heavy rains more easily and hold water reserves in case of drought and heat waves.

Healthy soil enables agriculture to adapt to climate extremes and is crucial for maintaining food production.

Agricultural practices based on soil regeneration also mean that farmers can count on fertile, productive soil that requires less fertilizer and synthetic pesticides. These synthetic pesticides, which pollute our waterways and can end up in our food, have become increasingly expensive and difficult to source. By using them less, we can make farms more resilient and better ensure our food security.

And as for human health? Recent studies have shown that healthy soil produces more nutritious food, bursting with minerals, vitamins and organic compounds like antioxidants. This, in turn, helps combat malnutrition and chronic disease.

'PEOPLE PROTECT WHAT THEY LOVE, THEY LOVE WHAT THEY UNDERSTAND'

A woman told us recently that in some parts of the world, when a person moves to a foreign country, they take a bit of garden soil with them so that if they get sick, they can use it to make a tisane that will restore their human gut microbiome. Becoming one with nature can take some surprising forms!

Équiterre will focus on soil health during the biodiversity COP15 in the coming weeks. We must highlight the strong linkages among soil biodiversity, food quality and human health.

If we as a society can gradually learn to understand and love our soil, the words of Jacques Cousteau would ring true, and we would raise our voices in unison to protect it. And protecting what we love means attacking what threatens it head-on. Urban sprawl and industrial encroachment are two such threats to our soils.

A small miracle – the gift that keeps giving – lies just beneath our feet. We have everything to gain by preserving it.

This opinion piece is written by:

- Carole-Anne Lapierre and Nadine Bachand, analysts at Équiterre
- Claudel Pétrin-Desrosiers, Physician and lecturer at the University of Montreal
- Marie-Élise Samson, Assistant professor in soil science at Université Laval
- Carole Poliquin, Director of the film 'Hummus'