Almstead Tree & Shrub Care Blog

Friday, May 6, 2011

Air Spading Again! - White Oaks in Pelham

Removing soil from the root flare of a buried White Oak
in Pelham's Harmon Park.
These 6 White Oaks (Quercus alba) located in Harmon Park in the heart of Pelham range in age from 80 to 120 years old. The primary original root flares of these trees have been buried throughout many years, most likely in attempts to grow grass. In some situations, the soil was almost 2 feet higher than it should be on the trunks.

Originally, Almstead was contracted by the town to prune this grove of White Oaks (a very valuable tree species, especially in maturity). When I discovered the soil compaction and deep burying of the root systems, I recommended that air spading be performed in order to improve the health and extend the lifespans of these specimen trees.

An air spade uses pressurized air to remove soil while
not causing harm to the root system of the tree
(or an utility lines that may run underground)
Once we began air spading, it was obvious that secondary or adventitious roots were forming, which are not viable as a stable root system for trees this size, as well as girdling roots. In addition to removing the excess soil, these roots were pruned away.

We also performed vertical mulching throughout the critical root zones of the trees (out to the edge of the canopies). We used the air spade again, but this time to dig 3" diameter holes 10" deep. The holes were spaced at 3 foot intervals throughout the root zones. This is a great way to reach the entire root system without tearing up a whole lawn!

Adding compost and soil amendments to vertical
mulching holes. These 10" deep holes allow us to
feed the extensive root systems of large trees
without removing large sections of grass.
After digging the holes, they were filled with organic compost and a combination of organic soil amendments, including humus, molasses, seaweed extract, and others. These amendments all help to invigorate the natural biological processes that keep soils and roots healthy. We also added zeolite, which is an organic product that keeps air passages in the soil open -- this is a great additive because air is an essential element of healthy soils (not just water, which seems more obvious).

This was discovered by me and recommended to be performed for preservation of these trees when we were contracted to prune the grove of primarily oaks throughout the park area, town hall, harmon park and memorial park.

- Ken Almstead, Arborist in Westchester and NYC