The Scent of Soil (or the lack thereof) Affects Your Mental Health
When was the last time you caught a whiff of fresh dirt?
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One of the reasons most of us love to get away to somewhere wild, or at least removed from the hustle and bustle of urban and suburban life, is to SMELL the great outdoors.
You know what I mean. That fresh sunlight kissed smell of being closer to nature than you are to other human beings. There is nothing quite like it to rejuvenate your mind and body.
It doesn’t matter if your getaway flavor is the ocean, the desert, the forest or the mountain top, the air smells different and your whole body drinks that in.
The foundation of that experience, and what makes each of these places unique, is the soil, even though we never think about it in that way. Where there is life, there is a living breathing soil community associated with it, as unique below ground as it is above.
I sometimes wonder if we “need” these getaways quite specifically to breathe that air and gain those volatile compounds directly into our systems.
It turns out that there is a scientific basis for this scent awareness found in healthy living soils. Because you are an ancient human being living in a modern world. And while your current life may not resemble anything like our collective hunter-gatherer past, you still retain incredible super-powers for navigating in your environment and detecting the richest natural resources that occur there.
Those rich natural resources are founded on living soils.
And it turns out you have a strong innate ability to detect whether soil is healthy or not.
If I handed you two different cups of soil, and told you to sniff them, the odds are highly in your favor that just from the first whiff you could tell me which cup came from healthy active soil and which one was just lifeless dirt.
And, I would bet money, that if I gave you 4 or 5 different cups of soil and asked you to rank them in order of goodness based on a sniff test, you could likely do that too even if you have never gardened a day in your life.
That’s because healthy soil contains micro-organisms (let’s just call them microbes for a shorter word) that release chemicals that make us feel good.
That’s right! Healthy soil makes you feel good.
Who knew?
Gardeners.
And your ancient human body.
How does smelling healthy soil make you feel good?
Our sense of smell is tied to the processing of memories and emotions in our brain through the limbic system. (You can read more about how we respond to the scent of food in the Mind-Body-Food Connection - Scentilicious Smells part 1 and part 2).
Breathing in the scent of fresh soil triggers your parasympathetic nervous system - that’s the one responsible for feeling calm, for getting digestion done, and for being in a relaxed state.
When we focus on a scent like fresh soil, we are breathing in our connection to the natural world. We are, quite literally, grounding ourself in nature, drawing in the volatile soil compounds through our nose and processing them in our brains.
In our increasingly microbe-phobic modern lifestyles, with all manner of antibacterial soaps and sprays, we forget that our human body cannot function without microbes. And where do these microbes come from? Our environment and our food.
A 2023 paper in the journal Urban Agriculture and Regional Food Systems has shown that after gardening in organic rich soils, participants had increased microbial presence on their skin for up to 12 hours later.
While some of you may be thinking - yikes grab that soap! - the reality is that we evolved in the natural world with protagonist and antagonist microbes that make our immune systems function. When we no longer put our hands in the soil, or breathe the organic compounds related to soil microbe activity, we are missing components that help create mental and physical wellbeing.
In much the same way that aromatherapy can alter your state of mind, the fresh scent of healthy soil does that too.
A daily soil practice?
Most of us cannot spend our whole life on vacation in one of those special places that makes breathing a sensual wonderland.
Yoga, meditation, and mindfulness practices are the current go-to methods of generating the calm and peace of mind you would otherwise be finding in nature.
But we can also create opportunities to connect with healthy soil directly and thereby gain the actual soil volatiles and microbes that support mental health through daily or weekly gardening sessions. Whether you are sowing seeds, removing weeds, or harvesting your bounty, gardening puts in you direct contact with, and in scenting distance of, soil on a regular basis. That makes summer the easiest time to benefit directly from soil microbiology.
And what about the rest of the time?
That’s where houseplants come in.
As I wrote previously in The Life-changing Benefits of Houseplants:
Soil that houseplants grow in has beneficial effects too
Did you know that having contact with soil - touching it, smelling it - can trigger serotonin release in your brain?
Serotonin is a neurotransmitter in your brain that facilitates long-lasting feelings of happiness and wellbeing. Bacteria in soil, specifically Mycobacterium vaccae, have been shown to trigger serotonin release. A 2022 study showed that just 5 minutes of mixing soil inoculated with M. vaccae was enough to trigger reduced heart rates and brain wave patterns indicative of calm and relaxation. Other soil bacteria, like Streptomyces rimosus are also being studied for their positive psychological and physiological effects on humans.
In the same way that our modern food systems have denied us our connection to real food, our modern lifestyles have largely eliminated our connection to natural soils.
I think it is important to remember that good health and mental wellbeing are not going to come out of box or pill bottle. They come from establishing practices that support us as living breathing human beings.
Down in the dirt might be an oxymoron
We associate the phrase ‘down in the dirt’ as being sad, fallen, on our knees. But what if there is a better metaphor hidden in there? One that speaks to how we gather up our goodness, our wellness, from the very ground at our feet and rise up again . . . how healthy soil actually makes us strong and well.
Think about that on your next getaway to the natural spot you love visiting. Breathe in those rich organic smells. Know that the soils where you stand are what help to create that unique plant community and atmosphere you are so enjoying.
And then remember that you could create the same sense of wellbeing right at home with a little healthy soil magic come gardening or houseplants.
What’s your favorite natural place to visit because it smells so good?
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