The use of a compressed air-powered tool, or AirSpade, facilitates excavation, soil management, and tree health-care within a tree’s critical root zone (CRZ). In fact, the proven benefits to tree health from air-spading has made it a preferred means for professional arborists. Unlike mechanical excavation techniques, air-spading efficiently removes or loosens soil without damaging a tree’s delicate root system. There are several common reasons for requiring the use of an AirSpade, all of which open new possibilities for landscape stewardship and construction involving valuable, established trees.
Root Zone Soil Management
The AirSpade can be used to mitigate many soil conditions that are unfavorable to a tree’s health, including soil that is overly compacted, poorly drained, anaerobic, or imbalanced in its physical or chemical composition. Depending on specific site conditions and proper evaluation by a certified arborist, an appropriate intervention can be chosen from a range of air-spading applications. Air tilling, radial trenching, and vertical mulching are examples of operations commonly used for soil management. Each can serve simply as a method of decompaction, which yields considerable health benefits to the tree, or used as an implementation method for soil augmentation.
Soil replacement is sometimes desirable for trees which have very poor soil, or where new landscape construction occurs around the existing tree. Examples may include urban trees with poor soils or the installation of sand-based or reinforced topsoils for high-use lawn areas. Air-tilling, full or partial bare-rooting, and soil blending are ideal applications for this type of work.
Corrections to Root Structure Corrections to a tree’s root system is another important operation involving the use of an AirSpade. Common issues include girdling roots caused by trees that are planted too low, have settled, or have soil built up at their base, heaving roots due to shallow depth of viable soil, or constricted growing space. These issues are often amplified in urban conditions with poor soils and tree pits that limit growth and pavements, which limit soil aeration and can be heaved by roots if a proper planting system is not provided. Air tilling can be useful to detect root defects and improper planting. Root collar excavation, root pruning, and bare rooting are applications that most commonly involve corrections to root structure.
Specialized Excavation for Construction
Lacking proper consideration, excavation to build foundations, install pavements, or install or maintain utilities can cause excessive damage to a tree’s critical root zone. Once necessary excavation is completed using an AirSpade, an arborist can prune and train roots as necessary and oversee care and protection of the tree during and after construction.
General Site Provisions
Proper site preparation, tree protection, and safety procedures are vital to the success of any project using an AirSpade.
Overall tree health is crucial prior to the use of an AirSpade. The project team, including a certified arborist, should evaluate trees to be impacted and ensure proper watering and health-care well in advance of the scheduled work. Tree health-care should also be scheduled for the period following the procedure, when trees can be especially susceptible to cold, injury, drought, and pests.
When using an AirSpade, it is important to perform a field moisture test to ensure that the soil is near field capacity but not saturated. If the soil is too dry, excess dust will be generated, and if too wet, the use of an AirSpade will spray mud and can destroy soil structure. Some AirSpade applications require the removal of turf or other plant material first. Turf within the work area should be treated with herbicide well in advance of air-spading, or it can be removed just prior to the operation. Shrubs and ground-covers can be either left in place or temporarily relocated.
Site protection plans should be developed with the landscape architect prior to the start of work. When working on a construction site, it is advisable to install tree protection fencing to restrict traffic within the critical root zone. Airborne stones or other particles can cause risk to nearby people and property within 25 feet (7.5 m) or more. Protective barriers (made from plywood or fabric) may be moved during the operation or fixed throughout the site as necessary.
The safety of the operator, and nearby people and property is of paramount importance when using compressed air powered tools such as an AirSpade. The use of these tools requires training and education beyond what is covered in this book. Always be sure to reference the tool manufacturer for their most updated safety procedures and operational materials.