The world beneath our feet
Soil is life.
Soil is the great enabler of life. An earthy substance that smells incredible and gets under your fingernails in the best way. Every gardener can attest to the mood-lifting qualities of putting their fingers in the dirt, and soil bacteria has actually been shown to stimulate the production of serotonin, one of our happy hormones.
It’s not just our wellbeing that the soil serves, either. This humble, crumbly stuff is what keeps all plant life alive. There’s a whole world down there - an intricate dance happening right under our feet, with ten times more life than above ground. It’s an ecosystem that exists in a delicate balance, and there are a whole lot of factors that go into keeping it happy and healthy.
Why is it important?
Soil is where plants, and all the other tiny organisms which support them, call home. It’s like any home, really, needing the right balance of food, air, water and a solid structure. A healthy soil ecosystem makes all these nutrients accessible to plant roots, allowing those plants to grow.
To put it simply, healthy soil will grow stronger, more nutrient-dense food for us to eat. As it becomes more and more important to develop food resilience in our communities, this is a major win. Plus, even if these plants aren’t for eating, they’ll be drawing down more carbon and emptying it from the atmosphere, where we all know we have too much. Double win.
So what’s soil made of?
It’s a combination of water, air, minerals and - this is the really juicy stuff - organic matter. Globally, most soil only has 0.8% of this organic matter, which is made up of organisms, roots and humus. It’s really important though, and ideally this figure would sit more around the 3% mark. In other words, we love organic matter, but when soil isn’t properly looked after, this is what gets depleted. Basically, it makes up the underground food chain that allows plants to absorb nutrients and keep growing.
Let’s look at it step by step, starting with the plants (or photosynthesizers). Harnessing the sunlight, they turn this into food for themselves and in doing so, feed carbon into the soil.
Enter the organisms, bacteria and fungi. These guys produce enzymes which break down the complex carbon excreted by the plants into smaller pieces.
Along come other tiny predators like earthworms - and some with fancy names like protozoa and nematode - which can then feed on these smaller bits of available carbon. They eat each other, too, excreting the right nutrients in a form that the plants can absorb. The ripe substance formed by this decomposition process is known as the humus.
The more different kinds of organisms there are, the better the biodiversity of the soil. Plants can then eat a varied diet and in turn grow nutritious kai for hungry communities. It’s like magic, really.
Soil heroes - how do we know our soil is good?
Let’s revisit bacteria and fungi, the heroes of the soil world, as their work isn’t done yet. As well as breaking down nutrients, they are an important element of the soil structure.
Good bacteria produces glues that help to form clumps in the soil, while fungi then binds these clumps together into a solid matrix. It’s this structure that determines what happens when soil gets wet. When it’s healthy, water can both be absorbed like a sponge, and flow through it, coming out clean and filtered.
When this microbial system is missing, however, the soil is packed too tightly for water to get in, and the top layer will simply be washed off instead.
There’s a lot wrong with that scenario. The topsoil layer will be lost at the first sign of rain and could cause damage to wherever it end ups. This is known as run-off, and often results in contamination of our waterways.
It also takes a lot of water to permeate soil like this. In fact, it’s said that a healthy soil food web can have half the irrigation requirements of compact, eroded soil. That’s a whole lot less water going down the drain!
A healthy soil ecosystem really does make the world go around, and so much of that comes down to the organic matter. That’s a lot of responsibility for some very tiny organisms, and they could use all the help they can get.
How can we look after our soil?
This beautiful ecosystem is complex, but there are simple practices we can keep to nourish it, whether we’re farmers, at-home gardeners or the guardians of any patch of land. We owe a lot to our soil, and it’s not enough to just try and tread lightly upon it - we need to be actively caring for this rich substance that nourishes all life on earth. After all, it’s our home!
Here are a few ways to have a regenerative influence on our soil:
Keep soil covered with crops all year round
Avoid pesticides and excess inputs of fertilisers (even organic ones)
Encourage biodiversity by growing lots of different plants
Ditch any chemicals
Compost - read a bit more about the benefits of composting and why homemade compost is the bees knees
Grow food
We’ve only scratched the surface, and of course there’s plenty more to the complex world of soil, microorganisms and life under our feet. We’ll explore it again soon, so stay tuned.
