Is Your Garden Soil The Picture of Health?
Here’s some basic soil science about making your garden soil the picture of health.
Earlier, we discussed how that regenerative farming is an agriculturally-positive, growing movement not just with local small-scale farmers and large commercial crop producers, but for the home gardener as well. The benefits of adopting regenerative farming techniques is that not only is it bringing sustainability toward how we treat the land, but that it can possibly affect climate change and reverse current trends toward global warming.
One of the primary ways regenerative farming is believed to reduce global warming is the sequestration of carbon in the soil. Sources state that soil organic matter contains over 50% carbon; and that worldwide, soils contain more carbon than that which is in both plants and the atmosphere combined. Therefore, the no-till foundation of regenerative farming makes sense when it comes to positing that there is a direct connection between years of conventional farming with its traditional tilling and ploughing of soil with the increase in carbon in the atmosphere that we see today.
The Soil-Carbon-Plant Cycle
So, how is this carbon sequestered in the soil. Basically, it is a chemically complex process that for our purposes is best thought of as a cyclic journey of carbon atoms that when left undisturbed revolves around and around in a never-ending cycle.
For example, we can start the trek with a plant absorbing carbon dioxide from the air around it, which in turn is converted into carbon-rich carbohydrates by the plant. These carbohydrates are released by the roots into the soil where they essentially feed a plethora of microorganisms and fungi in a microbiome that has a symbiotic relationship with the roots.
The carbohydrate food that feeds the microorganisms and fungi becomes degraded. The carbon atoms from the degraded carbohydrates in turn wind up “stored” in the soil in various forms, while the remainder of the carbon atoms are released through cellular respiration by the microorganisms. This cellular respiration creates carbon dioxide, which then completes the cycle as it leaves the soil and is reabsorbed by the plant.
This is analogous to thinking of the carbon cycle like a trip to the bank with a paycheck. Part of it is deposited into a savings account where it is sequestered for hopefully a long time, whereas the remainder is deposited into a checking account that is more fluid and spread out into the economy relatively quickly—some of which returns as your paycheck and a return trip to the bank where more money is added to the savings account.
However, disrupt the soil by ploughing the fields, and you will disrupt the cycle and thereby release that soil-stored carbon into the atmosphere and thus contribute to global warming.
The Importance of the Root System Microbiome
While the aforementioned soil and plant carbon cycle suits a basic description of what is going on with respect to soil health and plants, this is really just the tip of the iceberg lettuce. It turns out that the microbiome within which the microorganisms thrive near the roots is not much different than the microbiome in our gut.
In an article about microbiome research published in The Atlantic, soil bacteria and fungi are analogized as “…the "stomachs" of plants, which form symbiotic relationships with plant roots and digests nutrients, providing nitrogen, phosphorus, and many other nutrients in a form that plant cells can assimilate.”
And, just as we have “…unwittingly destroyed vital microbes in the human gut through overuse of antibiotics and highly processed foods, we have recklessly devastated soil microbiota essential to plant health through overuse of certain chemical fertilizers, fungicides, herbicides, pesticides, failure to add sufficient organic matter (upon which they feed), and heavy tillage.”
So, how do we cure or fix the “stomach of plants”? Similar to adding cultured yogurt to our diet—we need to add microbes and certain fungi to the soil to return to a healthier digestive environment.
One of the most important members of the natural microbiome that can be reintroduced to poor soil are the mycorrhizae (my-cor-rhi-zee). Mycorrhizal fungi are a filamentous organism that colonizes the roots of many plants, developing a "symbiotic" relationship that helps the plant be more efficient at obtaining nutrients and water. In return, the plant provides food and thus energy (in the form of carbohydrates in the soil-carbon-plant cycle described earlier) to the fungus.
Incredibly enough, those fungal filaments not only bring increased nutrients and water to the plant cells, but they also connect plants in a type of communications network used in natural plant defenses.
In addition, scientists believe that this vast network of mycorrhizal filaments is where much of the longer-stored soil carbon is sequestered. It turns out that the filaments are coated with a sticky protein called “glomalin,” with each molecule possessing a relatively massive amount of carbon atoms.
Final Thoughts: Making Your Garden Soil the Picture of Health
While many articles on soil health typically focus on adding organic material back to soils to restore them, research on the microbiomes surrounding the root system is telling us that adding more manure, topsoil and peat is only part of the picture. Just like the proverb, “It takes a village to raise a child”—it takes an entire ecosystem to feed a plant.
The point of this article was to add on a little more soil science to your understanding of what it takes to grow plants and how that you can begin to incorporate what science is learning about plant biology into your own garden.
A good way to get started on your soil health is following the practice and recommendations of this incredibly useful video of a lecture by a farmer explaining his principles of building a healthy soil successfully.
If you have any advice on how you keep your garden soil healthy, please feel free to let us know in the comments section below.
Timothy Boyer has a Ph.D. in Molecular and Cellular Biology from the University of Arizona. For 20+ years he has been employed as a freelance health and science writer. Today, with a background in farming and an avid home gardener, Timothy continues writing about science with a focus on the connection between plant biology and gardening for healthy living. For continual updates about plants and health, you can also follow Timothy on Twitter at TimBoyerWrites.
Image courtesy of Pixabay
“To Restore Our Soils, Feed the Microbes” by Matthew Wallenstein; TheConversation.com
“Healthy Soil Microbes, Healthy People” by Mike Amaranthus and Bruce Allyn; The Atlantic June 11, 2013.