Soil Health & How to Measure It
By Dave de Vries
I’d like to spend a few moments discussing Soil Health.
There is currently a lot of talk about soil health, soil biology and nutrient management in regenerative farming but how do you know if you are on the right track?
Let’s talk about soil.
Soil health can be recognized as the soil’s ability to function. With the mounting pressure to produce good nutrient-dense food, feed for increased overall health of animals, fibre for manufacturing and even for fuel; soil health is gaining attention around the globe. More research is being done on this subject than ever before and more media has been covering this topic as well. Take into consideration the example of the “Kiss the Ground” movie that was recently released. Some of those guys are acquaintances of mine and they attended our course with Graeme Sait in L.A. a few years ago. With Graeme’s teaching, they began their mission and are doing a great job reaching the masses. While there is good progress being made, there is still a long way to go.
So what is soil? Soil is the zone where rocks, organisms, air and water interact. It is not just the physical state that you see, hold and walk on; it has a biological state as well. The composition of soil is its main characteristic, and how nature or
human management determines the way it functions. Soil is filled with life as you may have seen in soil food web charts. The Natural Resources Conservation Service (NCRS) suggests that there could be more species of organisms in one shovel-full of garden soil than species that exist above the ground. The initial food source for all of these organisms is the broken down crop residue and root decay, as well as the exudates from the growing plants. In the same way that us humans need food to survive, so do these biota. In the farming or growing of any plant, it is the manager's responsibility to provide this excellent habitat for the ecosystem underneath our feet.
Many books and articles are written about soil health and a modern consensus states that it can be defined as:
“a continuing system of the soil to function as a vital living ecosystem that sustains plants, animals and humans” (NCRS).
As these organisms feed on the residue and exudates, they burn off or respire a lot of the carbon that they take in. They also keep some of the nutrients that they consume and in turn release it slowly or keep it from leaching away or running off with water. This activity of respiration can be used as a measurement of soil health as it is a sign of biological activity.
As this soil life is managed in a way that encourages and promotes a healthy biosphere, there is an overall reaction that takes place. Not only will these microbes break down minerals in the soil to be readily available to plant roots, but they also become microbes that integrate and connect themselves with the plant's roots. You have your nitrogen-fixing bacteria that create nodules on the root of the host plant. An excellent fungi that many are aware of is mycorrhizal fungi. It connects to the roots and increases the plant's nutrient uptake - especially phosphorus.
Healthy soil should have good tilth that has room for water and air to move through it and breathe. The healthy smell of nice soil is caused by the biology that exists within it…
Bacteria known as Actinomycetes thrive in moist warm soils with good levels of organic matter. When the soil dries up these organisms release a chemical compound called geosmin, which is a Greek word meaning “earth smell”. Many times as I have walked fields with farmers and as we dig plants, take soil samples and look at roots, we smell the soil together. It is a pleasant aroma when you can smell healthy soils and it’s great to see the smile on the faces of those I am with. Soils that are taken care of with management practices that build organic matter tend to require less added inputs and are more resilient to extreme weather patterns. When you take care of organic matter, you are essentially taking care of soil health.
In my travels and on many farms across North America, I have been able to see growers make changes to increase soil health. Using nutritional inputs and monitoring how to utilize practices that promote living soil is an increasingly popular way to farm.
Take time this winter to read more about soil and how to really take care of it. Read blogs and listen to podcasts from NTS & Graeme Sait, Joel Williams, and others. Plan your next growing season around the things you learn, and reap the benefits of your healthy soil. Let your soil work for you.
And as always, do not hesitate to reach out to me.
Dave de Vries