Soil restructuring is one of the most powerful tools we have for tree health management. The idea is to till the soil; improving its structure will allow valuable air and water to more easily penetrate the soil. While fundamental in gardening theory, this task is not easy at the scale of a large tree.
One of the first challenges we must deal with is maintaining tree roots while tilling the soil. After all, we are trying to help the trees here! This challenge is overcome by use of a tool called an airspade. An airspade is an over powered air compressor that blows away dirt without damaging the tree roots. There is just enough power to displace soil, but not enough to cut through roots.
In most scenarios, we will till the top 4-8” of soil depending on the site conditions. We’ll then add about 2” of finely ground mulch or other organic matter and then re-till the soil to get it all mixed up good. Once this part of the process is completed we’ll top dress it with about 4” of mulch.
The end product is an inviting soil that is great for growing anything. This is as close to mimicking a natural forest floor as we can get in an urban environment. Add a few small to mid size shrubs to provide an additional layer of shade to the soil surface and some irrigation and you’ll have a full blown tree utopia!