Part 2: Microbes
Good tree root health
In discussing root health, we have determined that oxygen is perhaps the most critical issue that will affect positive root growth and vigor in trees. The aerobic nature of soil is what facilitates the physiological processes that occur in the root zone of trees. Of course life is not so simple as "just add oxygen," though. In good soil there is a complex soil food web. Let's examine it.
Something that should be considered is that tree roots do not necessarily act alone in their function of absorption of water and nutrients from soil. Growing on the root caps of the fine feeder roots are tiny mycorrhizal fungi. These fungi engage in a symbiotic relationship with the tree. In return for carbohydrates that they are able to take from the photosynthetic tree, the fungi provide microscopic extensions that greatly increase the tree roots' ability to absorb water and minerals from the soil. The presence of these fungi on tree roots can make a tree much more resistant to drought stress and disease.
In the forest soil these microbes live in abundance. The forest floor provides an ideal environment for their propagation, and they are constantly cycling through the soil food web. In contrast, urban and suburban soil can be seriously lacking in these microbes. Heavy fertilization, disturbed and compacted soils, pesticides and fungicides, and low oxygen levels combine to provide a harsh environment for their propagation.
These microbes can be cultured or "brewed" in compost teas. The brewing process heavily aerates a compost solution that contains the spores of these microbes and some nutrients to get them activated. When matured, the tea is ready for introduction into the soil for the benefit of the soil food web. The benefit of a tea is much greater than a synthetic fertilizer because of its ability to restore the soil food web instead of simply dosing the soil with nitrogen.
If the soil being treated is heavily compacted, as is often the case in urban soil, it is not enough to simply spray the solution on the surface. The absorption barrier at the level of the compacted soil will stop the migration of water, microbes, and nutrients to a good depth. The absorption barrier must be broken so that the tea can be introduced. Vertical mulching and rootwell installation are the best ways to break this barrier and deliver the tea to where it will benefit root growth.
Work with your arborist to employ strategies that can bring the characteristics of forest soil to the soil in your trees' root zones. It's amazing what can happen when you apply nature's gifts to your property.
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More About Soil Remediation
Good Tree Root Health: Oxygen. In the tips of the roots where absorption takes place, oxygen is critical to root life.
Good Tree Root Health and Microbes. The forest floor provides an ideal environment for their propagation, and they are constantly cycling through the soil food web. In contrast, urban and suburban soil can be seriously lacking in these microbes.
Root Aeration Tubes There are numerous options for root aeration tubes. A popular design involves PVC plastic pipes.
Rootwell Products The Rootwell Products, direct-to-root system has been engineered to permanently enhance a tree's natural ability to absorb oxygen, water, and nutrients.
Soil Compaction In the built environment where most of us live, soil compaction is a necessity.
Soil Composition When we consider the make-up of soil we are looking at the percentages of three different components, sand, clay, and silt.
Soil Food Web What horticulturists and soil scientists refer to as the soil food web is an intricate network of life forms.
Soil Structure Soil structure essentially refers to the amount of macropores in the soil.
Tree Root Health: Watering Trees. What we see in lawns that are irrigated conventionally is tree roots growing at or near the surface in the only space that they can live.
Trees Suffering From Drought? Take a walk in an established forest in this area, and you will see that the problem is not really the drought.
Water Is Not Enough This tree is watered daily by an automatic irrigation system. Despite the abundance of water, it is stressed and losing leaves in July.
Why is That Tree Not Growing? Why is it that the trees in some landscapes never seem to grow past the half-way point of their mature size?