Glossary of Terms Used on Rootwell Products, Inc. Website
Restricted Root Space
According to experts such as James Urban, a 20” caliper tree will require 1,200 cubic feet of soil in order to thrive. Establishing this much space underground can be especially challenging in urban and suburban settings. Even if there is enough space, the conditions in the soil may not be such that would support root growth. All of the space designated for the roots of a tree must consist of the essential conditions for root growth. If these conditions are not present, then root growth will not occur and the space is wasted.
In urban and suburban settings, it is the challenge and charge of the designer to optimize the conditions of soil in a very specific – often confined – space for the roots of trees. Most often this will mean that oxygen will have to be provided to soil in spaces that would not naturally have an air exchange.
So establishment of urban and suburban trees requires deliberate design of the underground space involved in growing trees.
The composition of soil refers to the material that is in it. For the most part, when we consider the make-up of soil we are looking at the percentages of three different components, sand, clay, and silt. In order to be considered to be a fertile loam soil, there should be some of all these components. Differing levels of each of the components will affect the way that the soil absorbs water, retains water, and drains water. The composition also affects the compaction characteristics of soil.
When we speak of soil composition, we are generally referring to the A horizon of the soil, that layer that is just beneath the organic material on top (mostly decaying plant material) and above the parent material below. The organic materials interact with the parent materials in this layer and support what is known as the soil food web.
Generally speaking, an even mix of the three components (a little less clay, though) is optimum for root growth.
Soil Food Web
What horticulturists and soil scientists refer to as the soil food web is an intricate network of life forms, mostly microbial, that work together to create the support needed for the foliage above.
The two most important conditions for this network of life forms are oxygen and water. Beneficial fungi and bacteria that assist plant roots with the absorption of water require oxygen to live. Earthworms, which create channels for root growth as well as nutrients, must respire underground.
Aeration devices placed in the garden will broaden and deepen the profile of available oxygen and water for all of these organisms to live.
A more robust soil food web means a more robust garden!
Perhaps more important than the composition of soil is the structure of the soil. The soil composition will determine the amount of micropores that are present in the soil. Soil absorbs water into its mircropores and holds it. Because of the small size of the micropores, water does not drain from them. Drainage occurs through larger spaces in soil known as macropores. It is the drainage of water through these larger spaces that allows air to be drawn into the soil. Without air (Oxygen) roots cannot live.
So soil structure essentially refers to the amount of macropores in the soil.
Soil structure can be compromised by breaking it down during construction, over tilling, compacting it, or killing off the organisms that provide the structure. Organisms that create structure can be complex organisms such as earthworms that create rather large spaces in soil by tunneling through it. There are also microorganisms that contribute to soil structure by creating a glue known as Glomalin that holds pieces of soil together and preserves the macropores in soil.
All of the organisms that contribute to soil structure require oxygen to live. So if oxygen is not constantly available in the soil there will be no organisms in the soil food web to preserve the structure of the soil.
Use Less Chemicals
Chemicals and synthetic fertilizers in your garden can be a complicated – and sometimes counterproductive – part of your gardening efforts.
For example, did you know that fertilizers with more nitrogen than phosphorous can actually be harmful to your tomato crop? High levels of nitrogen will increase foliage and inhibit fruit production.
The truth about plants is that they create their own food through photosynthesis. If roots are growing in good soil and at proper depths, then plants will feed themselves. As the underground environment gets more healthy there is less need for amendments to the soil.
Aeration with Root Sticks promotes healthy, aerated, well-drained soil. The field capacity – the soil’s ability to hold water for plant consumption – is increased. With this increase comes more drainage, which is what pulls oxygen into the soil for a better soil food web.
Because water migrates downward instead of laterally in aerated soil, less water is needed to saturate the root zone.
Less chemicals, less fertilizer, and less water make your gardening a much more enjoyable experience.