Soil health and mental health

by Joseph Murray
June 24, 2019
Originally submitted to the Warm Springs Valley Garden Club Newsletter

Have you ever found yourself sitting in your garden, trowel in hand, gazing at nothing in particular, completely at peace with the world? Happens to me all of the time. I’m brought back to the “real world” when Anne rings the cottage porch bell signaling tea time or when a visitor rolls-up the driveway. I find it difficult to articulate the state of relaxation I experience in the garden during these special moments of attunement with nature. When I’m away working in a large urban environment, I find that no amount of meditation or Tai Chi provides the mental rejuvenation I achieve in our garden. I’m thankful for these peaceful moments and routinely set aside time to garden in a way that invites this union with nature.

Why do you garden? To produce flowers and vegetables? Based upon the time, resources, and effort you’re willing to expend, your garden probably reflects an agreement between you and nature to provide these material goods. I suspect you also derive enjoyment from your gardening exploits. Let’s bring this immaterial harvest (enjoyment) from the garden to your attention. If you knew there was a connection between gardening and improved mental health, would you garden differently? If your garden was part “medicine cabinet” and part “meditation studio,” would you adjust your preconception of a “proper” garden’s appearance?

Some beds that have been “co-created” with nature may appear chaotic but end up being sustainable and resilient throughout the growing season. Picture by J. Murray (June 24, 2019)

Feeling good in nature

Since science started exploring possible connections between human health and time spent in nature, there’s been a growing body of evidence that interacting with nature – “green space” in urban areas – is good for your mental health. The “dosage” of nature required to realize better psychological health may be as little as 2 hours a week, regardless of an individual’s age, sex, income, place of residence, or existing health conditions. A study of over 900,000 people found children exposed to green spaces were at lower risk to develop psychiatric disorders later in life. Sadly, those encountering the lowest amounts of green space during childhood were up to 55% more at risk to experience a mental illness than those encountering the highest amount of green space. The association remained even after the researchers adjusted for influencing variables like urbanization, socioeconomic factors, parental history of mental illness, and parental age.

Although researchers involved in this study found a strong correlation between green space and mental health, they admit the study doesn’t offer a causative mechanism(s). They speculated potential involvement of factors such as psychological restoration, opportunities for exercise, improvement of social coherence, decrease in noise and air pollution affecting cognition and brain development, and improvement in immune functioning may contribute to improved mental health. I’m particularly intrigued by the connection between immune function and mental health. New studies are confirming that stress can initiate inflammation which in turn contributes to a wide range of psychiatric disorders.

Anne relaxing in a sunny spot and giving herself permission to be still. Picture by J. Murray (June 24, 2019)

Feeling good in the garden

In addition to time spent in green spaces, a gardener may benefit from another mental health boost through exposure to gardening in healthy soil. A meta-analysis of 22 published case studies demonstrated the restorative powers of gardening in reducing stress, anger, fatigue, depression and anxiety.

A particular soil bacterium, Mycobacterium vaccae, is well documented as positively influencing the moods and immune systems of gardeners encountering it during gardening activities. When macrophages, special white blood cells in the gardener’s immune system, consume M. vaccae, a specific bacterial fatty acid is released that reduces inflammation and thus lessens the risk stress-related psychiatric disorders. Thank you, Mother Nature, for providing us with a stress vaccine that we may administer to ourselves… by gardening!

Medicinal plants, like soil, can produce mood altering compounds. Joe is planting a female Cannabis plant that will later be harvested for CBD. Picture by A. Bryan (June 24, 2019)

If the soil microbes aren’t happy… nobody’s happy

Gardeners have long appreciated the importance of healthy soil in creating sustainable and resilient gardens. Healthy soil, regardless how it is defined, is dependent upon soil biodiversity. The best way to improve soil health is to promote abundant and diverse populations of soil microorganisms. To promote soil life, consider eliminating practices and products that are harmful to living soil. Research shows that practices using organic growing systems experienced 32% to 84% greater microbial populations compared to “conventional” systems employing pesticides, routine applications of synthetic fertilizers, frequent tilling, and reduced amounts of organic matter. After all, nature has relegated the responsibility of plant nutrition to the life in soil, primarily to microorganisms like bacteria. Why bypass this natural system and use synthetic fertilizers which may upset the complex soil food web that regulates the very soil bacteria we are attempting to nurture? If you perceive the need to do something, compost. Feed the soil, not the plant.

I believe another reason why I find it difficult to find mental rejuvenation in urban environments is the absence of these mood-elevating bacteria. Although my inner-nature bends my steps to some urban areas (like a corporate office park) that appear to have vegetation, what I often find is a monoculture of Japanese hollies and ornamental pears growing out of a lifeless soil covered with colored mulch. The landscape architect’s design and horticulture practices responsible for this artificial landscape prevents nature from establishing the necessary biodiversity of plants above-ground to support biodiversity of microbes below-ground. Maybe it’s fanciful thinking, but it just feels to me that the absence of biodiversity contributes to my sense of alienation when walking in these artificial environments.

We grow a variety of hops… but not for the mind-numbing effects that follow the consumption of several hoppy beers. Our hops are used as an aid for sleep and digestion. Picture by J. Murray (June 24, 2019)

It’s good to get dirty

The hygiene hypothesis posits that children raised in a relatively sterile environment develop impaired immune systems and higher rates of allergies and asthma. This hypothesis is being expanded to include mental health development, as well. Researchers have observed that children raised in rural environments, with exposure to beneficial microbes (in dust from soil) experience more robust stress-related immune systems which typically lower the risk of mental illness compared to children raised in more urban environments. Factors contributing to hygienic environments and reduced exposure to beneficial bacteria include modern sanitary measures, antibiotic overuse, dietary changes, and little access for playing in gardens.

What’s in your garden’s soil?
Now that you are aware of connections between gardening and improved mental health, will you garden differently? Like me, perhaps you’ll schedule idle time to simple “be” in your garden and know that nature is working to rejuvenate your mental health. Perhaps you will adjust your preconceived ideas of a garden needing to be neat, tidy, and under-control. Co-creating with nature means there will be some surprises and a tendency to a state that’s not as “neat and tidy,” and certainly not under-control. That’s okay. You’re moving into a new kind of balance with nature with the goal of improving both your soil’s health and your mental health. Leave a little wildness in your garden. Nature may know what’s in your mental health’s best interest. That surprise emergence of a wildflower or, dare I say it – weed, may be a part of mother nature’s prescription to support microscopic pharmacists in your soil to aid in your mental health rejuvenation.

Who knew growing your medicine could be so enjoyable!

After spending some time in your garden and calming your mind, consider bringing a small chair or blanket and treat yourself to a short meditation. Picture by J. Murray (June 24, 2019)

References and Resources

White, M. (2019) Spending two hours a week in nature is linked to better health and well-being. 2019. The Conversation. June 13, 2019. Webpage last accessed June 20, 2019.
https://theconversation.com/spending-two-hours-a-week-in-nature-is-linked-to-better-health-and-well-being-118653

Kristine Engemann, Carsten Bøcker Pedersen, Lars Arge, Constantinos Tsirogiannis, Preben Bo Mortensen, Jens-Christian Svenning. (2019) Residential green space in childhood is associated with lower risk of psychiatric disorders from adolescence into adulthood. Proceedings of the National Academy of Sciences Mar 2019, 116 (11) 5188-5193; DOI: 10.1073/pnas.1807504116
https://www.researchgate.net/publication/331353080_Residential_green_space_in_childhood_is_associated_with_lower_risk_of_psychiatric_disorders_from_adolescence_into_adulthood

Lori M, Symnaczik S, Mäder P, De Deyn G, Gattinger A. (2017) Organic farming enhances soil microbial abundance and activity—A meta-analysis and meta-regression. PLoS ONE 12(7): e0180442. https://doi.org/10.1371/journal.pone.0180442

University of Colorado at Boulder. (2019, May 29). Healthy, stress-busting fat found hidden in dirt. ScienceDaily. Retrieved June 20, 2019 from www.sciencedaily.com/releases/2019/05/190529094003.htm

Schiffman, Richard (2017). Why It’s Time to Stop Punishing Our Soils with Fertilizers. Interview with Rick Haney (May 3, 2017). Yale Environment 360.
https://e360.yale.edu/features/why-its-time-to-stop-punishing-our-soils-with-fertilizers-and-chemicals

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